Trait VariantToJson 

pub trait VariantToJson {
    // Required methods
    fn to_json(&self, buffer: &mut impl Write) -> Result<(), ArrowError>;
    fn to_json_string(&self) -> Result<String, ArrowError>;
    fn to_json_value(&self) -> Result<Value, ArrowError>;
}

Extension trait for converting Variants to JSON

Required Methods

fn to_json(&self, buffer: &mut impl Write) -> Result<(), ArrowError>

This function writes JSON directly to any type that implements Write, making it efficient for streaming or when you want to control the output destination.

See VariantToJson::to_json_string for a convenience function that returns a JSON string.

Arguments

• writer - Writer to output JSON to
• variant - The Variant value to convert

Returns

• Ok(()) if successful
• Err with error details if conversion fails

Examples

let variant = Variant::from("Hello, World!");
let mut buffer = Vec::new();
variant.to_json(&mut buffer)?;
assert_eq!(String::from_utf8(buffer).unwrap(), "\"Hello, World!\"");

Example: Create a [Variant::Object] and convert to JSON

let mut builder = VariantBuilder::new();
// Create an object builder that will write fields to the object
let mut object_builder = builder.new_object();
object_builder.insert("first_name", "Jiaying");
object_builder.insert("last_name", "Li");
object_builder.finish();
// Finish the builder to get the metadata and value
let (metadata, value) = builder.finish();
// Create the Variant and convert to JSON
let variant = Variant::try_new(&metadata, &value)?;
let mut writer = Vec::new();
variant.to_json(&mut writer)?;
assert_eq!(br#"{"first_name":"Jiaying","last_name":"Li"}"#, writer.as_slice());

fn to_json_string(&self) -> Result<String, ArrowError>

Convert [Variant] to JSON String

This is a convenience function that converts a Variant to a JSON string. This is the same as calling VariantToJson::to_json with a Vec. It’s the simplest way to get a JSON representation when you just need a String result.

Arguments

• variant - The Variant value to convert

Returns

• Ok(String) containing the JSON representation
• Err with error details if conversion fails

Examples

let variant = Variant::Int32(42);
let json = variant.to_json_string()?;
assert_eq!(json, "42");

Example: Create a [Variant::Object] and convert to JSON

This example shows how to create an object with two fields and convert it to JSON:

{
  "first_name": "Jiaying",
  "last_name": "Li"
}

let mut builder = VariantBuilder::new();
// Create an object builder that will write fields to the object
let mut object_builder = builder.new_object();
object_builder.insert("first_name", "Jiaying");
object_builder.insert("last_name", "Li");
object_builder.finish();
// Finish the builder to get the metadata and value
let (metadata, value) = builder.finish();
// Create the Variant and convert to JSON
let variant = Variant::try_new(&metadata, &value)?;
let json = variant.to_json_string()?;
assert_eq!(r#"{"first_name":"Jiaying","last_name":"Li"}"#, json);

fn to_json_value(&self) -> Result<Value, ArrowError>

Convert [Variant] to serde_json::Value

This function converts a Variant to a serde_json::Value, which is useful when you need to work with the JSON data programmatically or integrate with other serde-based JSON processing.

Arguments

• variant - The Variant value to convert

Returns

• Ok(Value) containing the JSON value
• Err with error details if conversion fails

Examples

let variant = Variant::from("hello");
let json_value = variant.to_json_value()?;
assert_eq!(json_value, Value::String("hello".to_string()));

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementations on Foreign Types

impl<'m, 'v> VariantToJson for Variant<'m, 'v>

fn to_json(&self, buffer: &mut impl Write) -> Result<(), ArrowError>

fn to_json_string(&self) -> Result<String, ArrowError>

fn to_json_value(&self) -> Result<Value, ArrowError>

Implementors