Struct JsonFormatter

Source

pub struct JsonFormatter<'a, 'b> { /* private fields */ }

Expand description

A formatter for JSON values that controls the layout and formatting of the output.

JsonFormatter wraps the std::fmt::Formatter and provides methods specifically designed for generating well-formed JSON with customizable formatting options like indentation and spacing.

This formatter is primarily used when implementing the DisplayJson trait or when using the json() function for in-place JSON generation.

§Examples

Basic usage with the json() function:

use nojson::json;

// Generate compact JSON
let compact = json(|f| f.value([1, 2, 3]));
assert_eq!(compact.to_string(), "[1,2,3]");

// Generate pretty-printed JSON
let pretty = json(|f| {
    f.set_indent_size(2);
    f.set_spacing(true);
    f.value([1, 2, 3])
});

assert_eq!(
    format!("\n{}", pretty),
    r#"
[
  1,
  2,
  3
]"#
);

Implementations§

Source §

impl<'a, 'b> JsonFormatter<'a, 'b>

Source

pub fn value<T: DisplayJson>(&mut self, value: T) -> Result

Formats a value that implements the DisplayJson trait.

This is the primary method for writing a value to the JSON output.

§Examples

use nojson::json;

let output = json(|f| f.value([1, 2, 3]));
assert_eq!(output.to_string(), "[1,2,3]");

Source

pub fn string<T: Display>(&mut self, content: T) -> Result

Formats a value as a JSON string with proper escaping.

This method handles the necessary escaping of special characters in JSON strings, including quotes, backslashes, control characters, etc.

§Examples

use nojson::json;

let output = json(|f| f.string("Hello\nWorld"));
assert_eq!(output.to_string(), r#""Hello\nWorld""#);

Source

pub fn array<F>(&mut self, f: F) -> Result
where F: FnOnce(&mut JsonArrayFormatter<'a, 'b, '_>) -> Result,

Creates a JSON array with the provided formatting function.

This method starts a new JSON array and provides a JsonArrayFormatter to the callback function for adding elements to the array. It handles proper indentation, spacing, and brackets placement.

§Examples

use nojson::json;

let output = json(|f| {
    f.array(|f| {
        f.element(1)?;
        f.element(2)?;
        f.element(3)
    })
});
assert_eq!(output.to_string(), "[1,2,3]");

// With pretty-printing
let pretty = json(|f| {
    f.set_indent_size(2);
    f.set_spacing(true);
    f.array(|f| {
        f.element(1)?;
        f.element(2)?;
        f.element(3)
    })
});

Source

pub fn object<F>(&mut self, f: F) -> Result
where F: FnOnce(&mut JsonObjectFormatter<'a, 'b, '_>) -> Result,

Creates a JSON object with the provided formatting function.

This method starts a new JSON object and provides a JsonObjectFormatter to the callback function for adding members to the object. It handles proper indentation, spacing, and braces placement.

§Examples

use nojson::json;
use std::collections::HashMap;

let output = json(|f| {
    f.object(|f| {
        f.member("name", "Alice")?;
        f.member("age", 30)
    })
});
assert_eq!(output.to_string(), r#"{"name":"Alice","age":30}"#);

// With pretty-printing
let pretty = json(|f| {
    f.set_indent_size(2);
    f.set_spacing(true);
    f.object(|f| {
        f.member("name", "Alice")?;
        f.member("age", 30)
    })
});