Trait Assign

pub trait Assign {
    type Value;
    type Error;

    // Required method
    fn assign<V>(
        &mut self,
        ptr: &Pointer,
        value: V,
    ) -> Result<Option<Self::Value>, Self::Error>
       where V: Into<Self::Value>;
}

Implemented by types which can internally assign a (Value) at a path represented by a JSON Pointer.

Expansion

For provided implementations ("json", and "toml") path will automatically be expanded the if the Pointer is not fully exhausted before reaching a non-existent key in the case of objects, index in the case of arrays, or a scalar value (including null) based upon a best-guess effort on the meaning of each Token:

• If the Token is equal to "0" or "-", the token will be considered an index of an array.
• All tokens not equal to "0" or "-" will be considered keys of an object.

Examples

Successful assignment with replacement

This example demonstrates a successful assignment with replacement.

use jsonptr::{Pointer, assign::Assign};
use serde_json::{json, Value};

let mut data = json!({"foo": "bar"});
let ptr = Pointer::from_static("/foo");

let replaced = data.assign(&ptr, "baz").unwrap();
assert_eq!(replaced, Some(json!("bar")));
assert_eq!(data, json!({"foo": "baz"}));

Successful assignment with path expansion

This example demonstrates path expansion, including an array index ("0")

let ptr = Pointer::from_static("/foo/bar/0/baz");
let mut data = serde_json::json!({"foo": "bar"});

let replaced = data.assign(ptr, json!("qux")).unwrap();

assert_eq!(&data, &json!({"foo": {"bar": [{"baz": "qux"}]}}));
assert_eq!(replaced, Some(json!("bar")));

Successful assignment with "-" token

This example performs path expansion using the special "-" token (per RFC 6901) to represent the next element in an array.

let ptr = Pointer::from_static("/foo/bar/-/baz");
let mut data = json!({"foo": "bar"});

let replaced = data.assign(ptr, json!("qux")).unwrap();
assert_eq!(&data, &json!({"foo": {"bar": [{"baz": "qux"}]}}));
assert_eq!(replaced, Some(json!("bar")));

Required Associated Types

type Value

The type of value that this implementation can operate on.

type Error

Error associated with Assign

Required Methods

fn assign<V>( &mut self, ptr: &Pointer, value: V, ) -> Result<Option<Self::Value>, Self::Error>

where V: Into<Self::Value>,

Assigns a value of based on the path provided by a JSON Pointer, returning the replaced value, if any.

Errors

Returns Self::Error if the assignment fails.

Object Safety

This trait is not object safe.

Implementations on Foreign Types

impl Assign for Value

type Value = Value

type Error = AssignError

fn assign<V>( &mut self, ptr: &Pointer, value: V, ) -> Result<Option<Self::Value>, Self::Error>

where V: Into<Self::Value>,

Implementors