Trait JSONValue

Source

pub trait JSONValue {
    // Required method
    fn write_json<W: Write>(&self, w: &mut W) -> Result<()>;

    // Provided methods
    fn to_json_string(&self) -> String { ... }
    fn to_json_buffer(&self) -> Vec<u8> ⓘ { ... }
}

Expand description

A trait implemented by types that can be serialized to JSON

This trait can be derived for custom structs using json_in_type_derive

Required Methods§

Source

fn write_json<W: Write>(&self, w: &mut W) -> Result<()>

Write the object as json to the given writer

§Examples

Write a JSON object to a file

use json_in_type::JSONValue;

vec![1, 2, 3].write_json(&mut my_file);

Provided Methods§

Source

fn to_json_string(&self) -> String

Returns the object formatted as a json string

§Panics

If you implement JSONValue on your own types and emit invalid UTF-8 in write_json. If you use the implementations of JSONValue provided in this library, this function will never panic.

Source

fn to_json_buffer(&self) -> Vec<u8> ⓘ

Returns a buffer containing the bytes of a json representation of the object

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§

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impl<K: JSONString + Eq + Hash, V: JSONValue, S: BuildHasher> JSONValue for HashMap<K, V, S>

Serialize a HashMap to a JSON object. The property order is not guaranteed.

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fn write_json<W: Write>(&self, w: &mut W) -> Result<()>

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impl<T: JSONValue> JSONValue for Option<T>

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fn write_json<W: Write>(&self, w: &mut W) -> Result<()>

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impl<T: JSONValue> JSONValue for Vec<T>

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fn write_json<W: Write>(&self, w: &mut W) -> Result<()>

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impl<T: JSONValue, I: Iterator<Item = T>> JSONValue for RefCell<I>

Allows to serialize an iterator to JSON in a streaming fashion. The iterator needs to be wrapped in a RefCell because it will be consumed as JSON is written.

§Examples

§Serialize an iterator JSON

use std::cell::RefCell;
use std::iter::repeat;
use json_in_type::JSONValue;

let my_iter = repeat(42).take(3);
let my_iter_cell = RefCell::new(my_iter);

// The iterator will be consumed as json is produced
assert_eq!("[42,42,42]", my_iter_cell.to_json_string());

// Here, the iterator has already been consumed, so there is nothing left to serialize
assert_eq!("[]", my_iter_cell.to_json_string());

§Write a large JSON to a file

In this example, we take a potentially large input file, and serialize it to a JSON file containing an array with all the lines from the input file.

The output should look like this:

[
  {"line": 1, "contents": "a line of text"},
  {"line": 2, "contents": "another line of text"}
]

use std::cell::RefCell;
use std::io::BufRead;
use std::io::BufReader;
use json_in_type::*;


let json_lines = BufReader::new(input_file)
                .lines()
                .map(|l| l.unwrap())
                .enumerate()
                .map(|(i, contents)| json_object!{line:i+1, contents:contents});

RefCell::new(json_lines).write_json(&mut output_file);