arrow_schema/
field.rs

1// Licensed to the Apache Software Foundation (ASF) under one
2// or more contributor license agreements.  See the NOTICE file
3// distributed with this work for additional information
4// regarding copyright ownership.  The ASF licenses this file
5// to you under the Apache License, Version 2.0 (the
6// "License"); you may not use this file except in compliance
7// with the License.  You may obtain a copy of the License at
8//
9//   http://www.apache.org/licenses/LICENSE-2.0
10//
11// Unless required by applicable law or agreed to in writing,
12// software distributed under the License is distributed on an
13// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
14// KIND, either express or implied.  See the License for the
15// specific language governing permissions and limitations
16// under the License.
17
18use crate::error::ArrowError;
19use std::cmp::Ordering;
20use std::collections::HashMap;
21use std::hash::{Hash, Hasher};
22use std::sync::Arc;
23
24use crate::datatype::DataType;
25#[cfg(feature = "canonical_extension_types")]
26use crate::extension::CanonicalExtensionType;
27use crate::schema::SchemaBuilder;
28use crate::{
29    Fields, UnionFields, UnionMode,
30    extension::{EXTENSION_TYPE_METADATA_KEY, EXTENSION_TYPE_NAME_KEY, ExtensionType},
31};
32
33/// A reference counted [`Field`]
34pub type FieldRef = Arc<Field>;
35
36/// Describes a single column in a [`Schema`](super::Schema).
37///
38/// A [`Schema`](super::Schema) is an ordered collection of
39/// [`Field`] objects. Fields contain:
40/// * `name`: the name of the field
41/// * `data_type`: the type of the field
42/// * `nullable`: if the field is nullable
43/// * `metadata`: a map of key-value pairs containing additional custom metadata
44///
45/// Arrow Extension types, are encoded in `Field`s metadata. See
46/// [`Self::try_extension_type`] to retrieve the [`ExtensionType`], if any.
47#[derive(Clone)]
48#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
49pub struct Field {
50    name: String,
51    data_type: DataType,
52    nullable: bool,
53    #[deprecated(
54        since = "54.0.0",
55        note = "The ability to preserve dictionary IDs will be removed. With it, all fields related to it."
56    )]
57    dict_id: i64,
58    dict_is_ordered: bool,
59    /// A map of key-value pairs containing additional custom meta data.
60    metadata: HashMap<String, String>,
61}
62
63impl std::fmt::Debug for Field {
64    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
65        #![expect(deprecated)] // Must still print dict_id, if set
66        let Self {
67            name,
68            data_type,
69            nullable,
70            dict_id,
71            dict_is_ordered,
72            metadata,
73        } = self;
74
75        let mut s = f.debug_struct("Field");
76
77        if name != "item" {
78            // Keep it short when debug-formatting `DataType::List`
79            s.field("name", name);
80        }
81
82        s.field("data_type", data_type);
83
84        if *nullable {
85            s.field("nullable", nullable);
86        }
87
88        if *dict_id != 0 {
89            s.field("dict_id", dict_id);
90        }
91
92        if *dict_is_ordered {
93            s.field("dict_is_ordered", dict_is_ordered);
94        }
95
96        if !metadata.is_empty() {
97            s.field("metadata", metadata);
98        }
99        s.finish()
100    }
101}
102
103// Auto-derive `PartialEq` traits will pull `dict_id` and `dict_is_ordered`
104// into comparison. However, these properties are only used in IPC context
105// for matching dictionary encoded data. They are not necessary to be same
106// to consider schema equality. For example, in C++ `Field` implementation,
107// it doesn't contain these dictionary properties too.
108impl PartialEq for Field {
109    fn eq(&self, other: &Self) -> bool {
110        self.name == other.name
111            && self.data_type == other.data_type
112            && self.nullable == other.nullable
113            && self.metadata == other.metadata
114    }
115}
116
117impl Eq for Field {}
118
119impl PartialOrd for Field {
120    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
121        Some(self.cmp(other))
122    }
123}
124
125impl Ord for Field {
126    fn cmp(&self, other: &Self) -> Ordering {
127        self.name
128            .cmp(other.name())
129            .then_with(|| self.data_type.cmp(other.data_type()))
130            .then_with(|| self.nullable.cmp(&other.nullable))
131            .then_with(|| {
132                // ensure deterministic key order
133                let mut keys: Vec<&String> =
134                    self.metadata.keys().chain(other.metadata.keys()).collect();
135                keys.sort();
136                for k in keys {
137                    match (self.metadata.get(k), other.metadata.get(k)) {
138                        (None, None) => {}
139                        (Some(_), None) => {
140                            return Ordering::Less;
141                        }
142                        (None, Some(_)) => {
143                            return Ordering::Greater;
144                        }
145                        (Some(v1), Some(v2)) => match v1.cmp(v2) {
146                            Ordering::Equal => {}
147                            other => {
148                                return other;
149                            }
150                        },
151                    }
152                }
153
154                Ordering::Equal
155            })
156    }
157}
158
159impl Hash for Field {
160    fn hash<H: Hasher>(&self, state: &mut H) {
161        self.name.hash(state);
162        self.data_type.hash(state);
163        self.nullable.hash(state);
164
165        // ensure deterministic key order
166        let mut keys: Vec<&String> = self.metadata.keys().collect();
167        keys.sort();
168        for k in keys {
169            k.hash(state);
170            self.metadata.get(k).expect("key valid").hash(state);
171        }
172    }
173}
174
175impl AsRef<Field> for Field {
176    fn as_ref(&self) -> &Field {
177        self
178    }
179}
180
181impl Field {
182    /// Default list member field name
183    pub const LIST_FIELD_DEFAULT_NAME: &'static str = "item";
184
185    /// Creates a new field with the given name, data type, and nullability
186    ///
187    /// # Example
188    /// ```
189    /// # use arrow_schema::{Field, DataType};
190    /// Field::new("field_name", DataType::Int32, true);
191    /// ```
192    pub fn new(name: impl Into<String>, data_type: DataType, nullable: bool) -> Self {
193        #[allow(deprecated)]
194        Field {
195            name: name.into(),
196            data_type,
197            nullable,
198            dict_id: 0,
199            dict_is_ordered: false,
200            metadata: HashMap::default(),
201        }
202    }
203
204    /// Creates a new `Field` suitable for [`DataType::List`] and
205    /// [`DataType::LargeList`]
206    ///
207    /// While not required, this method follows the convention of naming the
208    /// `Field` `"item"`.
209    ///
210    /// # Example
211    /// ```
212    /// # use arrow_schema::{Field, DataType};
213    /// assert_eq!(
214    ///   Field::new("item", DataType::Int32, true),
215    ///   Field::new_list_field(DataType::Int32, true)
216    /// );
217    /// ```
218    pub fn new_list_field(data_type: DataType, nullable: bool) -> Self {
219        Self::new(Self::LIST_FIELD_DEFAULT_NAME, data_type, nullable)
220    }
221
222    /// Creates a new field that has additional dictionary information
223    #[deprecated(
224        since = "54.0.0",
225        note = "The ability to preserve dictionary IDs will be removed. With the dict_id field disappearing this function signature will change by removing the dict_id parameter."
226    )]
227    pub fn new_dict(
228        name: impl Into<String>,
229        data_type: DataType,
230        nullable: bool,
231        dict_id: i64,
232        dict_is_ordered: bool,
233    ) -> Self {
234        #[allow(deprecated)]
235        Field {
236            name: name.into(),
237            data_type,
238            nullable,
239            dict_id,
240            dict_is_ordered,
241            metadata: HashMap::default(),
242        }
243    }
244
245    /// Create a new [`Field`] with [`DataType::Dictionary`]
246    ///
247    /// Use [`Self::new_dict`] for more advanced dictionary options
248    ///
249    /// # Panics
250    ///
251    /// Panics if [`!key.is_dictionary_key_type`][DataType::is_dictionary_key_type]
252    pub fn new_dictionary(
253        name: impl Into<String>,
254        key: DataType,
255        value: DataType,
256        nullable: bool,
257    ) -> Self {
258        assert!(
259            key.is_dictionary_key_type(),
260            "{key} is not a valid dictionary key"
261        );
262        let data_type = DataType::Dictionary(Box::new(key), Box::new(value));
263        Self::new(name, data_type, nullable)
264    }
265
266    /// Create a new [`Field`] with [`DataType::Struct`]
267    ///
268    /// - `name`: the name of the [`DataType::Struct`] field
269    /// - `fields`: the description of each struct element
270    /// - `nullable`: if the [`DataType::Struct`] array is nullable
271    pub fn new_struct(name: impl Into<String>, fields: impl Into<Fields>, nullable: bool) -> Self {
272        Self::new(name, DataType::Struct(fields.into()), nullable)
273    }
274
275    /// Create a new [`Field`] with [`DataType::List`]
276    ///
277    /// - `name`: the name of the [`DataType::List`] field
278    /// - `value`: the description of each list element
279    /// - `nullable`: if the [`DataType::List`] array is nullable
280    pub fn new_list(name: impl Into<String>, value: impl Into<FieldRef>, nullable: bool) -> Self {
281        Self::new(name, DataType::List(value.into()), nullable)
282    }
283
284    /// Create a new [`Field`] with [`DataType::LargeList`]
285    ///
286    /// - `name`: the name of the [`DataType::LargeList`] field
287    /// - `value`: the description of each list element
288    /// - `nullable`: if the [`DataType::LargeList`] array is nullable
289    pub fn new_large_list(
290        name: impl Into<String>,
291        value: impl Into<FieldRef>,
292        nullable: bool,
293    ) -> Self {
294        Self::new(name, DataType::LargeList(value.into()), nullable)
295    }
296
297    /// Create a new [`Field`] with [`DataType::FixedSizeList`]
298    ///
299    /// - `name`: the name of the [`DataType::FixedSizeList`] field
300    /// - `value`: the description of each list element
301    /// - `size`: the size of the fixed size list
302    /// - `nullable`: if the [`DataType::FixedSizeList`] array is nullable
303    pub fn new_fixed_size_list(
304        name: impl Into<String>,
305        value: impl Into<FieldRef>,
306        size: i32,
307        nullable: bool,
308    ) -> Self {
309        Self::new(name, DataType::FixedSizeList(value.into(), size), nullable)
310    }
311
312    /// Create a new [`Field`] with [`DataType::Map`]
313    ///
314    /// - `name`: the name of the [`DataType::Map`] field
315    /// - `entries`: the name of the inner [`DataType::Struct`] field
316    /// - `keys`: the map keys
317    /// - `values`: the map values
318    /// - `sorted`: if the [`DataType::Map`] array is sorted
319    /// - `nullable`: if the [`DataType::Map`] array is nullable
320    pub fn new_map(
321        name: impl Into<String>,
322        entries: impl Into<String>,
323        keys: impl Into<FieldRef>,
324        values: impl Into<FieldRef>,
325        sorted: bool,
326        nullable: bool,
327    ) -> Self {
328        let data_type = DataType::Map(
329            Arc::new(Field::new(
330                entries.into(),
331                DataType::Struct(Fields::from([keys.into(), values.into()])),
332                false, // The inner map field is always non-nullable (#1697),
333            )),
334            sorted,
335        );
336        Self::new(name, data_type, nullable)
337    }
338
339    /// Create a new [`Field`] with [`DataType::Union`]
340    ///
341    /// - `name`: the name of the [`DataType::Union`] field
342    /// - `type_ids`: the union type ids
343    /// - `fields`: the union fields
344    /// - `mode`: the union mode
345    ///
346    /// # Panics
347    ///
348    /// Panics if:
349    /// - any type ID is negative
350    /// - type IDs contain duplicates
351    /// - the number of type IDs does not equal the number of fields
352    pub fn new_union<S, F, T>(name: S, type_ids: T, fields: F, mode: UnionMode) -> Self
353    where
354        S: Into<String>,
355        F: IntoIterator,
356        F::Item: Into<FieldRef>,
357        T: IntoIterator<Item = i8>,
358    {
359        Self::new(
360            name,
361            DataType::Union(
362                UnionFields::try_new(type_ids, fields).expect("Invalid UnionField"),
363                mode,
364            ),
365            false, // Unions cannot be nullable
366        )
367    }
368
369    /// Sets the `Field`'s optional custom metadata.
370    #[inline]
371    pub fn set_metadata(&mut self, metadata: HashMap<String, String>) {
372        self.metadata = metadata;
373    }
374
375    /// Sets the metadata of this `Field` to be `metadata` and returns self
376    pub fn with_metadata(mut self, metadata: HashMap<String, String>) -> Self {
377        self.set_metadata(metadata);
378        self
379    }
380
381    /// Returns the immutable reference to the `Field`'s optional custom metadata.
382    #[inline]
383    pub const fn metadata(&self) -> &HashMap<String, String> {
384        &self.metadata
385    }
386
387    /// Returns a mutable reference to the `Field`'s optional custom metadata.
388    #[inline]
389    pub fn metadata_mut(&mut self) -> &mut HashMap<String, String> {
390        &mut self.metadata
391    }
392
393    /// Returns an immutable reference to the `Field`'s name.
394    #[inline]
395    pub const fn name(&self) -> &String {
396        &self.name
397    }
398
399    /// Set the name of this [`Field`]
400    #[inline]
401    pub fn set_name(&mut self, name: impl Into<String>) {
402        self.name = name.into();
403    }
404
405    /// Set the name of the [`Field`] and returns self.
406    ///
407    /// ```
408    /// # use arrow_schema::*;
409    /// let field = Field::new("c1", DataType::Int64, false)
410    ///    .with_name("c2");
411    ///
412    /// assert_eq!(field.name(), "c2");
413    /// ```
414    pub fn with_name(mut self, name: impl Into<String>) -> Self {
415        self.set_name(name);
416        self
417    }
418
419    /// Returns an immutable reference to the [`Field`]'s  [`DataType`].
420    #[inline]
421    pub const fn data_type(&self) -> &DataType {
422        &self.data_type
423    }
424
425    /// Set [`DataType`] of the [`Field`]
426    ///
427    /// ```
428    /// # use arrow_schema::*;
429    /// let mut field = Field::new("c1", DataType::Int64, false);
430    /// field.set_data_type(DataType::Utf8);
431    ///
432    /// assert_eq!(field.data_type(), &DataType::Utf8);
433    /// ```
434    #[inline]
435    pub fn set_data_type(&mut self, data_type: DataType) {
436        self.data_type = data_type;
437    }
438
439    /// Set [`DataType`] of the [`Field`] and returns self.
440    ///
441    /// ```
442    /// # use arrow_schema::*;
443    /// let field = Field::new("c1", DataType::Int64, false)
444    ///    .with_data_type(DataType::Utf8);
445    ///
446    /// assert_eq!(field.data_type(), &DataType::Utf8);
447    /// ```
448    pub fn with_data_type(mut self, data_type: DataType) -> Self {
449        self.set_data_type(data_type);
450        self
451    }
452
453    /// Returns the extension type name of this [`Field`], if set.
454    ///
455    /// This returns the value of [`EXTENSION_TYPE_NAME_KEY`], if set in
456    /// [`Field::metadata`]. If the key is missing, there is no extension type
457    /// name and this returns `None`.
458    ///
459    /// # Example
460    ///
461    /// ```
462    /// # use arrow_schema::{DataType, extension::EXTENSION_TYPE_NAME_KEY, Field};
463    ///
464    /// let field = Field::new("", DataType::Null, false);
465    /// assert_eq!(field.extension_type_name(), None);
466    ///
467    /// let field = Field::new("", DataType::Null, false).with_metadata(
468    ///    [(EXTENSION_TYPE_NAME_KEY.to_owned(), "example".to_owned())]
469    ///        .into_iter()
470    ///        .collect(),
471    /// );
472    /// assert_eq!(field.extension_type_name(), Some("example"));
473    /// ```
474    pub fn extension_type_name(&self) -> Option<&str> {
475        self.metadata()
476            .get(EXTENSION_TYPE_NAME_KEY)
477            .map(String::as_ref)
478    }
479
480    /// Returns the extension type metadata of this [`Field`], if set.
481    ///
482    /// This returns the value of [`EXTENSION_TYPE_METADATA_KEY`], if set in
483    /// [`Field::metadata`]. If the key is missing, there is no extension type
484    /// metadata and this returns `None`.
485    ///
486    /// # Example
487    ///
488    /// ```
489    /// # use arrow_schema::{DataType, extension::EXTENSION_TYPE_METADATA_KEY, Field};
490    ///
491    /// let field = Field::new("", DataType::Null, false);
492    /// assert_eq!(field.extension_type_metadata(), None);
493    ///
494    /// let field = Field::new("", DataType::Null, false).with_metadata(
495    ///    [(EXTENSION_TYPE_METADATA_KEY.to_owned(), "example".to_owned())]
496    ///        .into_iter()
497    ///        .collect(),
498    /// );
499    /// assert_eq!(field.extension_type_metadata(), Some("example"));
500    /// ```
501    pub fn extension_type_metadata(&self) -> Option<&str> {
502        self.metadata()
503            .get(EXTENSION_TYPE_METADATA_KEY)
504            .map(String::as_ref)
505    }
506
507    /// Returns an instance of the given [`ExtensionType`] of this [`Field`],
508    /// if set in the [`Field::metadata`].
509    ///
510    /// Note that using `try_extension_type` with an extension type that does
511    /// not match the name in the metadata will return an `ArrowError` which can
512    /// be slow due to string allocations. If you only want to check if a
513    /// [`Field`] has a specific [`ExtensionType`], see the example below.
514    ///
515    /// # Errors
516    ///
517    /// Returns an error if
518    /// - this field does not have the name of this extension type
519    ///   ([`ExtensionType::NAME`]) in the [`Field::metadata`] (mismatch or
520    ///   missing)
521    /// - the deserialization of the metadata
522    ///   ([`ExtensionType::deserialize_metadata`]) fails
523    /// - the construction of the extension type ([`ExtensionType::try_new`])
524    ///   fail (for example when the [`Field::data_type`] is not supported by
525    ///   the extension type ([`ExtensionType::supports_data_type`]))
526    ///
527    /// # Examples: Check and retrieve an extension type
528    /// You can use this to check if a [`Field`] has a specific
529    /// [`ExtensionType`] and retrieve it:
530    /// ```
531    /// # use arrow_schema::{DataType, Field, ArrowError};
532    /// # use arrow_schema::extension::ExtensionType;
533    /// # struct MyExtensionType;
534    /// # impl ExtensionType for MyExtensionType {
535    /// # const NAME: &'static str = "my_extension";
536    /// # type Metadata = String;
537    /// # fn supports_data_type(&self, data_type: &DataType) -> Result<(), ArrowError> { Ok(()) }
538    /// # fn try_new(data_type: &DataType, metadata: Self::Metadata) -> Result<Self, ArrowError> { Ok(Self) }
539    /// # fn serialize_metadata(&self) -> Option<String> { unimplemented!() }
540    /// # fn deserialize_metadata(s: Option<&str>) -> Result<Self::Metadata, ArrowError> { unimplemented!() }
541    /// # fn metadata(&self) -> &<Self as ExtensionType>::Metadata { todo!() }
542    /// # }
543    /// # fn get_field() -> Field { Field::new("field", DataType::Null, false) }
544    /// let field = get_field();
545    /// if let Ok(extension_type) = field.try_extension_type::<MyExtensionType>() {
546    ///   // do something with extension_type
547    /// }
548    /// ```
549    ///
550    /// # Example: Checking if a field has a specific extension type first
551    ///
552    /// Since `try_extension_type` returns an error, it is more
553    /// efficient to first check if the name matches before calling
554    /// `try_extension_type`:
555    /// ```
556    /// # use arrow_schema::{DataType, Field, ArrowError};
557    /// # use arrow_schema::extension::ExtensionType;
558    /// # struct MyExtensionType;
559    /// # impl ExtensionType for MyExtensionType {
560    /// # const NAME: &'static str = "my_extension";
561    /// # type Metadata = String;
562    /// # fn supports_data_type(&self, data_type: &DataType) -> Result<(), ArrowError> { Ok(()) }
563    /// # fn try_new(data_type: &DataType, metadata: Self::Metadata) -> Result<Self, ArrowError> { Ok(Self) }
564    /// # fn serialize_metadata(&self) -> Option<String> { unimplemented!() }
565    /// # fn deserialize_metadata(s: Option<&str>) -> Result<Self::Metadata, ArrowError> { unimplemented!() }
566    /// # fn metadata(&self) -> &<Self as ExtensionType>::Metadata { todo!() }
567    /// # }
568    /// # fn get_field() -> Field { Field::new("field", DataType::Null, false) }
569    /// let field = get_field();
570    /// // First check if the name matches before calling the potentially expensive `try_extension_type`
571    /// if field.extension_type_name() == Some(MyExtensionType::NAME) {
572    ///   if let Ok(extension_type) = field.try_extension_type::<MyExtensionType>() {
573    ///     // do something with extension_type
574    ///   }
575    /// }
576    /// ```
577    pub fn try_extension_type<E: ExtensionType>(&self) -> Result<E, ArrowError> {
578        // Check the extension name in the metadata
579        match self.extension_type_name() {
580            // It should match the name of the given extension type
581            Some(name) if name == E::NAME => {
582                // Deserialize the metadata and try to construct the extension
583                // type
584                E::deserialize_metadata(self.extension_type_metadata())
585                    .and_then(|metadata| E::try_new(self.data_type(), metadata))
586            }
587            // Name mismatch
588            Some(name) => Err(ArrowError::InvalidArgumentError(format!(
589                "Field extension type name mismatch, expected {}, found {name}",
590                E::NAME
591            ))),
592            // Name missing
593            None => Err(ArrowError::InvalidArgumentError(
594                "Field extension type name missing".to_owned(),
595            )),
596        }
597    }
598
599    /// Returns an instance of the given [`ExtensionType`] of this [`Field`],
600    /// panics if this [`Field`] does not have this extension type.
601    ///
602    /// # Panic
603    ///
604    /// This calls [`Field::try_extension_type`] and panics when it returns an
605    /// error.
606    pub fn extension_type<E: ExtensionType>(&self) -> E {
607        self.try_extension_type::<E>()
608            .unwrap_or_else(|e| panic!("{e}"))
609    }
610
611    /// Updates the metadata of this [`Field`] with the [`ExtensionType::NAME`]
612    /// and [`ExtensionType::metadata`] of the given [`ExtensionType`], if the
613    /// given extension type supports the [`Field::data_type`] of this field
614    /// ([`ExtensionType::supports_data_type`]).
615    ///
616    /// If the given extension type defines no metadata, a previously set
617    /// value of [`EXTENSION_TYPE_METADATA_KEY`] is cleared.
618    ///
619    /// # Error
620    ///
621    /// This functions returns an error if the data type of this field does not
622    /// match any of the supported storage types of the given extension type.
623    pub fn try_with_extension_type<E: ExtensionType>(
624        &mut self,
625        extension_type: E,
626    ) -> Result<(), ArrowError> {
627        // Make sure the data type of this field is supported
628        extension_type.supports_data_type(&self.data_type)?;
629
630        self.metadata
631            .insert(EXTENSION_TYPE_NAME_KEY.to_owned(), E::NAME.to_owned());
632        match extension_type.serialize_metadata() {
633            Some(metadata) => self
634                .metadata
635                .insert(EXTENSION_TYPE_METADATA_KEY.to_owned(), metadata),
636            // If this extension type has no metadata, we make sure to
637            // clear previously set metadata.
638            None => self.metadata.remove(EXTENSION_TYPE_METADATA_KEY),
639        };
640
641        Ok(())
642    }
643
644    /// Updates the metadata of this [`Field`] with the [`ExtensionType::NAME`]
645    /// and [`ExtensionType::metadata`] of the given [`ExtensionType`].
646    ///
647    /// # Panics
648    ///
649    /// This calls [`Field::try_with_extension_type`] and panics when it
650    /// returns an error.
651    pub fn with_extension_type<E: ExtensionType>(mut self, extension_type: E) -> Self {
652        self.try_with_extension_type(extension_type)
653            .unwrap_or_else(|e| panic!("{e}"));
654        self
655    }
656
657    /// Returns the [`CanonicalExtensionType`] of this [`Field`], if set.
658    ///
659    /// # Error
660    ///
661    /// Returns an error if
662    /// - this field does not have a canonical extension type (mismatch or missing)
663    /// - the canonical extension is not supported
664    /// - the construction of the extension type fails
665    #[cfg(feature = "canonical_extension_types")]
666    pub fn try_canonical_extension_type(&self) -> Result<CanonicalExtensionType, ArrowError> {
667        CanonicalExtensionType::try_from(self)
668    }
669
670    /// Indicates whether this [`Field`] supports null values.
671    ///
672    /// If true, the field *may* contain null values.
673    #[inline]
674    pub const fn is_nullable(&self) -> bool {
675        self.nullable
676    }
677
678    /// Set the `nullable` of this [`Field`].
679    ///
680    /// ```
681    /// # use arrow_schema::*;
682    /// let mut field = Field::new("c1", DataType::Int64, false);
683    /// field.set_nullable(true);
684    ///
685    /// assert_eq!(field.is_nullable(), true);
686    /// ```
687    #[inline]
688    pub fn set_nullable(&mut self, nullable: bool) {
689        self.nullable = nullable;
690    }
691
692    /// Set `nullable` of the [`Field`] and returns self.
693    ///
694    /// ```
695    /// # use arrow_schema::*;
696    /// let field = Field::new("c1", DataType::Int64, false)
697    ///    .with_nullable(true);
698    ///
699    /// assert_eq!(field.is_nullable(), true);
700    /// ```
701    pub fn with_nullable(mut self, nullable: bool) -> Self {
702        self.set_nullable(nullable);
703        self
704    }
705
706    /// Returns a (flattened) [`Vec`] containing all child [`Field`]s
707    /// within `self` contained within this field (including `self`)
708    pub(crate) fn fields(&self) -> Vec<&Field> {
709        let mut collected_fields = vec![self];
710        collected_fields.append(&mut Field::_fields(&self.data_type));
711
712        collected_fields
713    }
714
715    fn _fields(dt: &DataType) -> Vec<&Field> {
716        match dt {
717            DataType::Struct(fields) => fields.iter().flat_map(|f| f.fields()).collect(),
718            DataType::Union(fields, _) => fields.iter().flat_map(|(_, f)| f.fields()).collect(),
719            DataType::List(field)
720            | DataType::LargeList(field)
721            | DataType::FixedSizeList(field, _)
722            | DataType::Map(field, _) => field.fields(),
723            DataType::Dictionary(_, value_field) => Field::_fields(value_field.as_ref()),
724            DataType::RunEndEncoded(_, field) => field.fields(),
725            _ => vec![],
726        }
727    }
728
729    /// Returns a vector containing all (potentially nested) `Field` instances selected by the
730    /// dictionary ID they use
731    #[inline]
732    #[deprecated(
733        since = "54.0.0",
734        note = "The ability to preserve dictionary IDs will be removed. With it, all fields related to it."
735    )]
736    pub(crate) fn fields_with_dict_id(&self, id: i64) -> Vec<&Field> {
737        self.fields()
738            .into_iter()
739            .filter(|&field| {
740                #[allow(deprecated)]
741                let matching_dict_id = field.dict_id == id;
742                matches!(field.data_type(), DataType::Dictionary(_, _)) && matching_dict_id
743            })
744            .collect()
745    }
746
747    /// Returns the dictionary ID, if this is a dictionary type.
748    #[inline]
749    #[deprecated(
750        since = "54.0.0",
751        note = "The ability to preserve dictionary IDs will be removed. With it, all fields related to it."
752    )]
753    pub const fn dict_id(&self) -> Option<i64> {
754        match self.data_type {
755            #[allow(deprecated)]
756            DataType::Dictionary(_, _) => Some(self.dict_id),
757            _ => None,
758        }
759    }
760
761    /// Returns whether this `Field`'s dictionary is ordered, if this is a dictionary type.
762    ///
763    /// # Example
764    /// ```
765    /// # use arrow_schema::{DataType, Field};
766    /// // non dictionaries do not have a dict is ordered flat
767    /// let field = Field::new("c1", DataType::Int64, false);
768    /// assert_eq!(field.dict_is_ordered(), None);
769    /// // by default dictionary is not ordered
770    /// let field = Field::new("c1", DataType::Dictionary(Box::new(DataType::Int64), Box::new(DataType::Utf8)), false);
771    /// assert_eq!(field.dict_is_ordered(), Some(false));
772    /// let field = field.with_dict_is_ordered(true);
773    /// assert_eq!(field.dict_is_ordered(), Some(true));
774    /// ```
775    #[inline]
776    pub const fn dict_is_ordered(&self) -> Option<bool> {
777        match self.data_type {
778            DataType::Dictionary(_, _) => Some(self.dict_is_ordered),
779            _ => None,
780        }
781    }
782
783    /// Set the is ordered field for this `Field`, if it is a dictionary.
784    ///
785    /// Does nothing if this is not a dictionary type.
786    ///
787    /// See [`Field::dict_is_ordered`] for more information.
788    pub fn with_dict_is_ordered(mut self, dict_is_ordered: bool) -> Self {
789        if matches!(self.data_type, DataType::Dictionary(_, _)) {
790            self.dict_is_ordered = dict_is_ordered;
791        };
792        self
793    }
794
795    /// Merge this field into self if it is compatible.
796    ///
797    /// Struct fields are merged recursively.
798    ///
799    /// NOTE: `self` may be updated to a partial / unexpected state in case of merge failure.
800    ///
801    /// Example:
802    ///
803    /// ```
804    /// # use arrow_schema::*;
805    /// let mut field = Field::new("c1", DataType::Int64, false);
806    /// assert!(field.try_merge(&Field::new("c1", DataType::Int64, true)).is_ok());
807    /// assert!(field.is_nullable());
808    /// ```
809    pub fn try_merge(&mut self, from: &Field) -> Result<(), ArrowError> {
810        if from.dict_is_ordered != self.dict_is_ordered {
811            return Err(ArrowError::SchemaError(format!(
812                "Fail to merge schema field '{}' because from dict_is_ordered = {} does not match {}",
813                self.name, from.dict_is_ordered, self.dict_is_ordered
814            )));
815        }
816        // merge metadata
817        match (self.metadata().is_empty(), from.metadata().is_empty()) {
818            (false, false) => {
819                let mut merged = self.metadata().clone();
820                for (key, from_value) in from.metadata() {
821                    if let Some(self_value) = self.metadata.get(key) {
822                        if self_value != from_value {
823                            return Err(ArrowError::SchemaError(format!(
824                                "Fail to merge field '{}' due to conflicting metadata data value for key {}.
825                                    From value = {} does not match {}", self.name, key, from_value, self_value),
826                            ));
827                        }
828                    } else {
829                        merged.insert(key.clone(), from_value.clone());
830                    }
831                }
832                self.set_metadata(merged);
833            }
834            (true, false) => {
835                self.set_metadata(from.metadata().clone());
836            }
837            _ => {}
838        }
839        match &mut self.data_type {
840            DataType::Struct(nested_fields) => match &from.data_type {
841                DataType::Struct(from_nested_fields) => {
842                    let mut builder = SchemaBuilder::new();
843                    nested_fields
844                        .iter()
845                        .chain(from_nested_fields)
846                        .try_for_each(|f| builder.try_merge(f))?;
847                    *nested_fields = builder.finish().fields;
848                }
849                _ => {
850                    return Err(ArrowError::SchemaError(format!(
851                        "Fail to merge schema field '{}' because the from data_type = {} is not DataType::Struct",
852                        self.name, from.data_type
853                    )));
854                }
855            },
856            DataType::Union(nested_fields, _) => match &from.data_type {
857                DataType::Union(from_nested_fields, _) => {
858                    nested_fields.try_merge(from_nested_fields)?
859                }
860                _ => {
861                    return Err(ArrowError::SchemaError(format!(
862                        "Fail to merge schema field '{}' because the from data_type = {} is not DataType::Union",
863                        self.name, from.data_type
864                    )));
865                }
866            },
867            DataType::List(field) => match &from.data_type {
868                DataType::List(from_field) => {
869                    let mut f = (**field).clone();
870                    f.try_merge(from_field)?;
871                    (*field) = Arc::new(f);
872                }
873                _ => {
874                    return Err(ArrowError::SchemaError(format!(
875                        "Fail to merge schema field '{}' because the from data_type = {} is not DataType::List",
876                        self.name, from.data_type
877                    )));
878                }
879            },
880            DataType::LargeList(field) => match &from.data_type {
881                DataType::LargeList(from_field) => {
882                    let mut f = (**field).clone();
883                    f.try_merge(from_field)?;
884                    (*field) = Arc::new(f);
885                }
886                _ => {
887                    return Err(ArrowError::SchemaError(format!(
888                        "Fail to merge schema field '{}' because the from data_type = {} is not DataType::LargeList",
889                        self.name, from.data_type
890                    )));
891                }
892            },
893            DataType::Null => {
894                self.nullable = true;
895                self.data_type = from.data_type.clone();
896            }
897            DataType::Boolean
898            | DataType::Int8
899            | DataType::Int16
900            | DataType::Int32
901            | DataType::Int64
902            | DataType::UInt8
903            | DataType::UInt16
904            | DataType::UInt32
905            | DataType::UInt64
906            | DataType::Float16
907            | DataType::Float32
908            | DataType::Float64
909            | DataType::Timestamp(_, _)
910            | DataType::Date32
911            | DataType::Date64
912            | DataType::Time32(_)
913            | DataType::Time64(_)
914            | DataType::Duration(_)
915            | DataType::Binary
916            | DataType::LargeBinary
917            | DataType::BinaryView
918            | DataType::Interval(_)
919            | DataType::LargeListView(_)
920            | DataType::ListView(_)
921            | DataType::Map(_, _)
922            | DataType::Dictionary(_, _)
923            | DataType::RunEndEncoded(_, _)
924            | DataType::FixedSizeList(_, _)
925            | DataType::FixedSizeBinary(_)
926            | DataType::Utf8
927            | DataType::LargeUtf8
928            | DataType::Utf8View
929            | DataType::Decimal32(_, _)
930            | DataType::Decimal64(_, _)
931            | DataType::Decimal128(_, _)
932            | DataType::Decimal256(_, _) => {
933                if from.data_type == DataType::Null {
934                    self.nullable = true;
935                } else if self.data_type != from.data_type {
936                    return Err(ArrowError::SchemaError(format!(
937                        "Fail to merge schema field '{}' because the from data_type = {} does not equal {}",
938                        self.name, from.data_type, self.data_type
939                    )));
940                }
941            }
942        }
943        self.nullable |= from.nullable;
944
945        Ok(())
946    }
947
948    /// Check to see if `self` is a superset of `other` field. Superset is defined as:
949    ///
950    /// * if nullability doesn't match, self needs to be nullable
951    /// * self.metadata is a superset of other.metadata
952    /// * all other fields are equal
953    pub fn contains(&self, other: &Field) -> bool {
954        self.name == other.name
955        && self.data_type.contains(&other.data_type)
956        && self.dict_is_ordered == other.dict_is_ordered
957        // self need to be nullable or both of them are not nullable
958        && (self.nullable || !other.nullable)
959        // make sure self.metadata is a superset of other.metadata
960        && other.metadata.iter().all(|(k, v1)| {
961            self.metadata.get(k).map(|v2| v1 == v2).unwrap_or_default()
962        })
963    }
964
965    /// Return size of this instance in bytes.
966    ///
967    /// Includes the size of `Self`.
968    pub fn size(&self) -> usize {
969        std::mem::size_of_val(self) - std::mem::size_of_val(&self.data_type)
970            + self.data_type.size()
971            + self.name.capacity()
972            + (std::mem::size_of::<(String, String)>() * self.metadata.capacity())
973            + self
974                .metadata
975                .iter()
976                .map(|(k, v)| k.capacity() + v.capacity())
977                .sum::<usize>()
978    }
979}
980
981impl std::fmt::Display for Field {
982    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
983        #![expect(deprecated)] // Must still print dict_id, if set
984        let Self {
985            name,
986            data_type,
987            nullable,
988            dict_id,
989            dict_is_ordered,
990            metadata,
991        } = self;
992        let maybe_nullable = if *nullable { "nullable " } else { "" };
993        let metadata_str = if metadata.is_empty() {
994            String::new()
995        } else {
996            format!(", metadata: {metadata:?}")
997        };
998        let dict_id_str = if dict_id == &0 {
999            String::new()
1000        } else {
1001            format!(", dict_id: {dict_id}")
1002        };
1003        let dict_is_ordered_str = if *dict_is_ordered {
1004            ", dict_is_ordered"
1005        } else {
1006            ""
1007        };
1008        write!(
1009            f,
1010            "Field {{ {name:?}: {maybe_nullable}{data_type}{dict_id_str}{dict_is_ordered_str}{metadata_str} }}"
1011        )
1012    }
1013}
1014
1015#[cfg(test)]
1016mod test {
1017    use super::*;
1018    use std::collections::hash_map::DefaultHasher;
1019
1020    #[test]
1021    fn test_new_with_string() {
1022        // Fields should allow owned Strings to support reuse
1023        let s = "c1";
1024        Field::new(s, DataType::Int64, false);
1025    }
1026
1027    #[test]
1028    fn test_new_dict_with_string() {
1029        // Fields should allow owned Strings to support reuse
1030        let s = "c1";
1031        #[allow(deprecated)]
1032        Field::new_dict(s, DataType::Int64, false, 4, false);
1033    }
1034
1035    #[test]
1036    #[cfg_attr(miri, ignore)] // Can't handle the inlined strings of the assert_debug_snapshot macro
1037    fn test_debug_format_field() {
1038        // Make sure the `Debug` formatting of `Field` is readable and not too long
1039        insta::assert_debug_snapshot!(Field::new("item", DataType::UInt8, false), @r"
1040        Field {
1041            data_type: UInt8,
1042        }
1043        ");
1044        insta::assert_debug_snapshot!(Field::new("column", DataType::LargeUtf8, true), @r#"
1045        Field {
1046            name: "column",
1047            data_type: LargeUtf8,
1048            nullable: true,
1049        }
1050        "#);
1051    }
1052
1053    #[test]
1054    fn test_merge_incompatible_types() {
1055        let mut field = Field::new("c1", DataType::Int64, false);
1056        let result = field
1057            .try_merge(&Field::new("c1", DataType::Float32, true))
1058            .expect_err("should fail")
1059            .to_string();
1060        assert_eq!(
1061            "Schema error: Fail to merge schema field 'c1' because the from data_type = Float32 does not equal Int64",
1062            result
1063        );
1064    }
1065
1066    #[test]
1067    fn test_merge_with_null() {
1068        let mut field1 = Field::new("c1", DataType::Null, true);
1069        field1
1070            .try_merge(&Field::new("c1", DataType::Float32, false))
1071            .expect("should widen type to nullable float");
1072        assert_eq!(Field::new("c1", DataType::Float32, true), field1);
1073
1074        let mut field2 = Field::new("c2", DataType::Utf8, false);
1075        field2
1076            .try_merge(&Field::new("c2", DataType::Null, true))
1077            .expect("should widen type to nullable utf8");
1078        assert_eq!(Field::new("c2", DataType::Utf8, true), field2);
1079    }
1080
1081    #[test]
1082    fn test_merge_with_nested_null() {
1083        let mut struct1 = Field::new(
1084            "s1",
1085            DataType::Struct(Fields::from(vec![Field::new(
1086                "inner",
1087                DataType::Float32,
1088                false,
1089            )])),
1090            false,
1091        );
1092
1093        let struct2 = Field::new(
1094            "s2",
1095            DataType::Struct(Fields::from(vec![Field::new(
1096                "inner",
1097                DataType::Null,
1098                false,
1099            )])),
1100            true,
1101        );
1102
1103        struct1
1104            .try_merge(&struct2)
1105            .expect("should widen inner field's type to nullable float");
1106        assert_eq!(
1107            Field::new(
1108                "s1",
1109                DataType::Struct(Fields::from(vec![Field::new(
1110                    "inner",
1111                    DataType::Float32,
1112                    true,
1113                )])),
1114                true,
1115            ),
1116            struct1
1117        );
1118
1119        let mut list1 = Field::new(
1120            "l1",
1121            DataType::List(Field::new("inner", DataType::Float32, false).into()),
1122            false,
1123        );
1124
1125        let list2 = Field::new(
1126            "l2",
1127            DataType::List(Field::new("inner", DataType::Null, false).into()),
1128            true,
1129        );
1130
1131        list1
1132            .try_merge(&list2)
1133            .expect("should widen inner field's type to nullable float");
1134        assert_eq!(
1135            Field::new(
1136                "l1",
1137                DataType::List(Field::new("inner", DataType::Float32, true).into()),
1138                true,
1139            ),
1140            list1
1141        );
1142
1143        let mut large_list1 = Field::new(
1144            "ll1",
1145            DataType::LargeList(Field::new("inner", DataType::Float32, false).into()),
1146            false,
1147        );
1148
1149        let large_list2 = Field::new(
1150            "ll2",
1151            DataType::LargeList(Field::new("inner", DataType::Null, false).into()),
1152            true,
1153        );
1154
1155        large_list1
1156            .try_merge(&large_list2)
1157            .expect("should widen inner field's type to nullable float");
1158        assert_eq!(
1159            Field::new(
1160                "ll1",
1161                DataType::LargeList(Field::new("inner", DataType::Float32, true).into()),
1162                true,
1163            ),
1164            large_list1
1165        );
1166    }
1167
1168    #[test]
1169    fn test_fields_with_dict_id() {
1170        #[allow(deprecated)]
1171        let dict1 = Field::new_dict(
1172            "dict1",
1173            DataType::Dictionary(DataType::Utf8.into(), DataType::Int32.into()),
1174            false,
1175            10,
1176            false,
1177        );
1178        #[allow(deprecated)]
1179        let dict2 = Field::new_dict(
1180            "dict2",
1181            DataType::Dictionary(DataType::Int32.into(), DataType::Int8.into()),
1182            false,
1183            20,
1184            false,
1185        );
1186
1187        let field = Field::new(
1188            "struct<dict1, list[struct<dict2, list[struct<dict1]>]>",
1189            DataType::Struct(Fields::from(vec![
1190                dict1.clone(),
1191                Field::new(
1192                    "list[struct<dict1, list[struct<dict2>]>]",
1193                    DataType::List(Arc::new(Field::new(
1194                        "struct<dict1, list[struct<dict2>]>",
1195                        DataType::Struct(Fields::from(vec![
1196                            dict1.clone(),
1197                            Field::new(
1198                                "list[struct<dict2>]",
1199                                DataType::List(Arc::new(Field::new(
1200                                    "struct<dict2>",
1201                                    DataType::Struct(vec![dict2.clone()].into()),
1202                                    false,
1203                                ))),
1204                                false,
1205                            ),
1206                        ])),
1207                        false,
1208                    ))),
1209                    false,
1210                ),
1211            ])),
1212            false,
1213        );
1214
1215        #[allow(deprecated)]
1216        for field in field.fields_with_dict_id(10) {
1217            assert_eq!(dict1, *field);
1218        }
1219        #[allow(deprecated)]
1220        for field in field.fields_with_dict_id(20) {
1221            assert_eq!(dict2, *field);
1222        }
1223    }
1224
1225    fn get_field_hash(field: &Field) -> u64 {
1226        let mut s = DefaultHasher::new();
1227        field.hash(&mut s);
1228        s.finish()
1229    }
1230
1231    #[test]
1232    fn test_field_comparison_case() {
1233        // dictionary-encoding properties not used for field comparison
1234        #[allow(deprecated)]
1235        let dict1 = Field::new_dict(
1236            "dict1",
1237            DataType::Dictionary(DataType::Utf8.into(), DataType::Int32.into()),
1238            false,
1239            10,
1240            false,
1241        );
1242        #[allow(deprecated)]
1243        let dict2 = Field::new_dict(
1244            "dict1",
1245            DataType::Dictionary(DataType::Utf8.into(), DataType::Int32.into()),
1246            false,
1247            20,
1248            false,
1249        );
1250
1251        assert_eq!(dict1, dict2);
1252        assert_eq!(get_field_hash(&dict1), get_field_hash(&dict2));
1253
1254        #[allow(deprecated)]
1255        let dict1 = Field::new_dict(
1256            "dict0",
1257            DataType::Dictionary(DataType::Utf8.into(), DataType::Int32.into()),
1258            false,
1259            10,
1260            false,
1261        );
1262
1263        assert_ne!(dict1, dict2);
1264        assert_ne!(get_field_hash(&dict1), get_field_hash(&dict2));
1265    }
1266
1267    #[test]
1268    fn test_field_comparison_metadata() {
1269        let f1 = Field::new("x", DataType::Binary, false).with_metadata(HashMap::from([
1270            (String::from("k1"), String::from("v1")),
1271            (String::from("k2"), String::from("v2")),
1272        ]));
1273        let f2 = Field::new("x", DataType::Binary, false).with_metadata(HashMap::from([
1274            (String::from("k1"), String::from("v1")),
1275            (String::from("k3"), String::from("v3")),
1276        ]));
1277        let f3 = Field::new("x", DataType::Binary, false).with_metadata(HashMap::from([
1278            (String::from("k1"), String::from("v1")),
1279            (String::from("k3"), String::from("v4")),
1280        ]));
1281
1282        assert!(f1.cmp(&f2).is_lt());
1283        assert!(f2.cmp(&f3).is_lt());
1284        assert!(f1.cmp(&f3).is_lt());
1285    }
1286
1287    #[test]
1288    #[expect(clippy::needless_borrows_for_generic_args)] // intentional to exercise various references
1289    fn test_field_as_ref() {
1290        let field = || Field::new("x", DataType::Binary, false);
1291
1292        // AsRef can be used in a function accepting a field.
1293        // However, this case actually works a bit better when function takes `&Field`
1294        fn accept_ref(_: impl AsRef<Field>) {}
1295
1296        accept_ref(field());
1297        accept_ref(&field());
1298        accept_ref(&&field());
1299        accept_ref(Arc::new(field()));
1300        accept_ref(&Arc::new(field()));
1301        accept_ref(&&Arc::new(field()));
1302
1303        // AsRef can be used in a function accepting a collection of fields in any form,
1304        // such as &[Field], or &[Arc<Field>]
1305        fn accept_refs(_: impl IntoIterator<Item: AsRef<Field>>) {}
1306
1307        accept_refs(vec![field()]);
1308        accept_refs(vec![&field()]);
1309        accept_refs(vec![Arc::new(field())]);
1310        accept_refs(vec![&Arc::new(field())]);
1311        accept_refs(&vec![field()]);
1312        accept_refs(&vec![&field()]);
1313        accept_refs(&vec![Arc::new(field())]);
1314        accept_refs(&vec![&Arc::new(field())]);
1315    }
1316
1317    #[test]
1318    fn test_contains_reflexivity() {
1319        let mut field = Field::new("field1", DataType::Float16, false);
1320        field.set_metadata(HashMap::from([
1321            (String::from("k0"), String::from("v0")),
1322            (String::from("k1"), String::from("v1")),
1323        ]));
1324        assert!(field.contains(&field))
1325    }
1326
1327    #[test]
1328    fn test_contains_transitivity() {
1329        let child_field = Field::new("child1", DataType::Float16, false);
1330
1331        let mut field1 = Field::new(
1332            "field1",
1333            DataType::Struct(Fields::from(vec![child_field])),
1334            false,
1335        );
1336        field1.set_metadata(HashMap::from([(String::from("k1"), String::from("v1"))]));
1337
1338        let mut field2 = Field::new("field1", DataType::Struct(Fields::default()), true);
1339        field2.set_metadata(HashMap::from([(String::from("k2"), String::from("v2"))]));
1340        field2.try_merge(&field1).unwrap();
1341
1342        let mut field3 = Field::new("field1", DataType::Struct(Fields::default()), false);
1343        field3.set_metadata(HashMap::from([(String::from("k3"), String::from("v3"))]));
1344        field3.try_merge(&field2).unwrap();
1345
1346        assert!(field2.contains(&field1));
1347        assert!(field3.contains(&field2));
1348        assert!(field3.contains(&field1));
1349
1350        assert!(!field1.contains(&field2));
1351        assert!(!field1.contains(&field3));
1352        assert!(!field2.contains(&field3));
1353    }
1354
1355    #[test]
1356    fn test_contains_nullable() {
1357        let field1 = Field::new("field1", DataType::Boolean, true);
1358        let field2 = Field::new("field1", DataType::Boolean, false);
1359        assert!(field1.contains(&field2));
1360        assert!(!field2.contains(&field1));
1361    }
1362
1363    #[test]
1364    fn test_contains_must_have_same_fields() {
1365        let child_field1 = Field::new("child1", DataType::Float16, false);
1366        let child_field2 = Field::new("child2", DataType::Float16, false);
1367
1368        let field1 = Field::new(
1369            "field1",
1370            DataType::Struct(vec![child_field1.clone()].into()),
1371            true,
1372        );
1373        let field2 = Field::new(
1374            "field1",
1375            DataType::Struct(vec![child_field1, child_field2].into()),
1376            true,
1377        );
1378
1379        assert!(!field1.contains(&field2));
1380        assert!(!field2.contains(&field1));
1381
1382        // UnionFields with different type ID
1383        let field1 = Field::new(
1384            "field1",
1385            DataType::Union(
1386                UnionFields::try_new(
1387                    vec![1, 2],
1388                    vec![
1389                        Field::new("field1", DataType::UInt8, true),
1390                        Field::new("field3", DataType::Utf8, false),
1391                    ],
1392                )
1393                .unwrap(),
1394                UnionMode::Dense,
1395            ),
1396            true,
1397        );
1398        let field2 = Field::new(
1399            "field1",
1400            DataType::Union(
1401                UnionFields::try_new(
1402                    vec![1, 3],
1403                    vec![
1404                        Field::new("field1", DataType::UInt8, false),
1405                        Field::new("field3", DataType::Utf8, false),
1406                    ],
1407                )
1408                .unwrap(),
1409                UnionMode::Dense,
1410            ),
1411            true,
1412        );
1413        assert!(!field1.contains(&field2));
1414
1415        // UnionFields with same type ID
1416        let field1 = Field::new(
1417            "field1",
1418            DataType::Union(
1419                UnionFields::try_new(
1420                    vec![1, 2],
1421                    vec![
1422                        Field::new("field1", DataType::UInt8, true),
1423                        Field::new("field3", DataType::Utf8, false),
1424                    ],
1425                )
1426                .unwrap(),
1427                UnionMode::Dense,
1428            ),
1429            true,
1430        );
1431        let field2 = Field::new(
1432            "field1",
1433            DataType::Union(
1434                UnionFields::try_new(
1435                    vec![1, 2],
1436                    vec![
1437                        Field::new("field1", DataType::UInt8, false),
1438                        Field::new("field3", DataType::Utf8, false),
1439                    ],
1440                )
1441                .unwrap(),
1442                UnionMode::Dense,
1443            ),
1444            true,
1445        );
1446        assert!(field1.contains(&field2));
1447    }
1448
1449    #[cfg(feature = "serde")]
1450    fn assert_binary_serde_round_trip(field: Field) {
1451        let config = bincode::config::legacy();
1452        let serialized = bincode::serde::encode_to_vec(&field, config).unwrap();
1453        let (deserialized, _): (Field, _) =
1454            bincode::serde::decode_from_slice(&serialized, config).unwrap();
1455        assert_eq!(field, deserialized)
1456    }
1457
1458    #[cfg(feature = "serde")]
1459    #[test]
1460    fn test_field_without_metadata_serde() {
1461        let field = Field::new("name", DataType::Boolean, true);
1462        assert_binary_serde_round_trip(field)
1463    }
1464
1465    #[cfg(feature = "serde")]
1466    #[test]
1467    fn test_field_with_empty_metadata_serde() {
1468        let field = Field::new("name", DataType::Boolean, false).with_metadata(HashMap::new());
1469
1470        assert_binary_serde_round_trip(field)
1471    }
1472
1473    #[cfg(feature = "serde")]
1474    #[test]
1475    fn test_field_with_nonempty_metadata_serde() {
1476        let mut metadata = HashMap::new();
1477        metadata.insert("hi".to_owned(), "".to_owned());
1478        let field = Field::new("name", DataType::Boolean, false).with_metadata(metadata);
1479
1480        assert_binary_serde_round_trip(field)
1481    }
1482}
arrow_schema/field.rs

arrow_schema/
field.rs
