[][src]Enum lightql::Value

pub enum Value {
    Null,
    Bool(bool),
    Number(Number),
    String(String),
    Array(Vec<Value>),
    Object(Map<String, Value>),
}

Represents any valid JSON value.

See the serde_json::value module documentation for usage examples.

Variants

Represents a JSON null value.

let v = json!(null);

Represents a JSON boolean.

let v = json!(true);

Represents a JSON number, whether integer or floating point.

let v = json!(12.5);

Represents a JSON string.

let v = json!("a string");

Represents a JSON array.

let v = json!(["an", "array"]);

Represents a JSON object.

By default the map is backed by a BTreeMap. Enable the preserve_order feature of serde_json to use IndexMap instead, which preserves entries in the order they are inserted into the map. In particular, this allows JSON data to be deserialized into a Value and serialized to a string while retaining the order of map keys in the input.

let v = json!({ "an": "object" });

Methods

impl Value
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Index into a JSON array or map. A string index can be used to access a value in a map, and a usize index can be used to access an element of an array.

Returns None if the type of self does not match the type of the index, for example if the index is a string and self is an array or a number. Also returns None if the given key does not exist in the map or the given index is not within the bounds of the array.

let object = json!({ "A": 65, "B": 66, "C": 67 });
assert_eq!(*object.get("A").unwrap(), json!(65));

let array = json!([ "A", "B", "C" ]);
assert_eq!(*array.get(2).unwrap(), json!("C"));

assert_eq!(array.get("A"), None);

Square brackets can also be used to index into a value in a more concise way. This returns Value::Null in cases where get would have returned None.

let object = json!({
    "A": ["a", "á", "à"],
    "B": ["b", "b́"],
    "C": ["c", "ć", "ć̣", "ḉ"],
});
assert_eq!(object["B"][0], json!("b"));

assert_eq!(object["D"], json!(null));
assert_eq!(object[0]["x"]["y"]["z"], json!(null));

Mutably index into a JSON array or map. A string index can be used to access a value in a map, and a usize index can be used to access an element of an array.

Returns None if the type of self does not match the type of the index, for example if the index is a string and self is an array or a number. Also returns None if the given key does not exist in the map or the given index is not within the bounds of the array.

let mut object = json!({ "A": 65, "B": 66, "C": 67 });
*object.get_mut("A").unwrap() = json!(69);

let mut array = json!([ "A", "B", "C" ]);
*array.get_mut(2).unwrap() = json!("D");

Returns true if the Value is an Object. Returns false otherwise.

For any Value on which is_object returns true, as_object and as_object_mut are guaranteed to return the map representation of the object.

let obj = json!({ "a": { "nested": true }, "b": ["an", "array"] });

assert!(obj.is_object());
assert!(obj["a"].is_object());

// array, not an object
assert!(!obj["b"].is_object());

If the Value is an Object, returns the associated Map. Returns None otherwise.

let v = json!({ "a": { "nested": true }, "b": ["an", "array"] });

// The length of `{"nested": true}` is 1 entry.
assert_eq!(v["a"].as_object().unwrap().len(), 1);

// The array `["an", "array"]` is not an object.
assert_eq!(v["b"].as_object(), None);

If the Value is an Object, returns the associated mutable Map. Returns None otherwise.

let mut v = json!({ "a": { "nested": true } });

v["a"].as_object_mut().unwrap().clear();
assert_eq!(v, json!({ "a": {} }));

Returns true if the Value is an Array. Returns false otherwise.

For any Value on which is_array returns true, as_array and as_array_mut are guaranteed to return the vector representing the array.

let obj = json!({ "a": ["an", "array"], "b": { "an": "object" } });

assert!(obj["a"].is_array());

// an object, not an array
assert!(!obj["b"].is_array());

If the Value is an Array, returns the associated vector. Returns None otherwise.

let v = json!({ "a": ["an", "array"], "b": { "an": "object" } });

// The length of `["an", "array"]` is 2 elements.
assert_eq!(v["a"].as_array().unwrap().len(), 2);

// The object `{"an": "object"}` is not an array.
assert_eq!(v["b"].as_array(), None);

If the Value is an Array, returns the associated mutable vector. Returns None otherwise.

let mut v = json!({ "a": ["an", "array"] });

v["a"].as_array_mut().unwrap().clear();
assert_eq!(v, json!({ "a": [] }));

Returns true if the Value is a String. Returns false otherwise.

For any Value on which is_string returns true, as_str is guaranteed to return the string slice.

let v = json!({ "a": "some string", "b": false });

assert!(v["a"].is_string());

// The boolean `false` is not a string.
assert!(!v["b"].is_string());

If the Value is a String, returns the associated str. Returns None otherwise.

let v = json!({ "a": "some string", "b": false });

assert_eq!(v["a"].as_str(), Some("some string"));

// The boolean `false` is not a string.
assert_eq!(v["b"].as_str(), None);

// JSON values are printed in JSON representation, so strings are in quotes.
//
//    The value is: "some string"
println!("The value is: {}", v["a"]);

// Rust strings are printed without quotes.
//
//    The value is: some string
println!("The value is: {}", v["a"].as_str().unwrap());

Returns true if the Value is a Number. Returns false otherwise.

let v = json!({ "a": 1, "b": "2" });

assert!(v["a"].is_number());

// The string `"2"` is a string, not a number.
assert!(!v["b"].is_number());

Returns true if the Value is an integer between i64::MIN and i64::MAX.

For any Value on which is_i64 returns true, as_i64 is guaranteed to return the integer value.

let big = i64::max_value() as u64 + 10;
let v = json!({ "a": 64, "b": big, "c": 256.0 });

assert!(v["a"].is_i64());

// Greater than i64::MAX.
assert!(!v["b"].is_i64());

// Numbers with a decimal point are not considered integers.
assert!(!v["c"].is_i64());

Returns true if the Value is an integer between zero and u64::MAX.

For any Value on which is_u64 returns true, as_u64 is guaranteed to return the integer value.

let v = json!({ "a": 64, "b": -64, "c": 256.0 });

assert!(v["a"].is_u64());

// Negative integer.
assert!(!v["b"].is_u64());

// Numbers with a decimal point are not considered integers.
assert!(!v["c"].is_u64());

Returns true if the Value is a number that can be represented by f64.

For any Value on which is_f64 returns true, as_f64 is guaranteed to return the floating point value.

Currently this function returns true if and only if both is_i64 and is_u64 return false but this is not a guarantee in the future.

let v = json!({ "a": 256.0, "b": 64, "c": -64 });

assert!(v["a"].is_f64());

// Integers.
assert!(!v["b"].is_f64());
assert!(!v["c"].is_f64());

If the Value is an integer, represent it as i64 if possible. Returns None otherwise.

let big = i64::max_value() as u64 + 10;
let v = json!({ "a": 64, "b": big, "c": 256.0 });

assert_eq!(v["a"].as_i64(), Some(64));
assert_eq!(v["b"].as_i64(), None);
assert_eq!(v["c"].as_i64(), None);

If the Value is an integer, represent it as u64 if possible. Returns None otherwise.

let v = json!({ "a": 64, "b": -64, "c": 256.0 });

assert_eq!(v["a"].as_u64(), Some(64));
assert_eq!(v["b"].as_u64(), None);
assert_eq!(v["c"].as_u64(), None);

If the Value is a number, represent it as f64 if possible. Returns None otherwise.

let v = json!({ "a": 256.0, "b": 64, "c": -64 });

assert_eq!(v["a"].as_f64(), Some(256.0));
assert_eq!(v["b"].as_f64(), Some(64.0));
assert_eq!(v["c"].as_f64(), Some(-64.0));

Returns true if the Value is a Boolean. Returns false otherwise.

For any Value on which is_boolean returns true, as_bool is guaranteed to return the boolean value.

let v = json!({ "a": false, "b": "false" });

assert!(v["a"].is_boolean());

// The string `"false"` is a string, not a boolean.
assert!(!v["b"].is_boolean());

If the Value is a Boolean, returns the associated bool. Returns None otherwise.

let v = json!({ "a": false, "b": "false" });

assert_eq!(v["a"].as_bool(), Some(false));

// The string `"false"` is a string, not a boolean.
assert_eq!(v["b"].as_bool(), None);

Returns true if the Value is a Null. Returns false otherwise.

For any Value on which is_null returns true, as_null is guaranteed to return Some(()).

let v = json!({ "a": null, "b": false });

assert!(v["a"].is_null());

// The boolean `false` is not null.
assert!(!v["b"].is_null());

If the Value is a Null, returns (). Returns None otherwise.

let v = json!({ "a": null, "b": false });

assert_eq!(v["a"].as_null(), Some(()));

// The boolean `false` is not null.
assert_eq!(v["b"].as_null(), None);

Looks up a value by a JSON Pointer.

JSON Pointer defines a string syntax for identifying a specific value within a JavaScript Object Notation (JSON) document.

A Pointer is a Unicode string with the reference tokens separated by /. Inside tokens / is replaced by ~1 and ~ is replaced by ~0. The addressed value is returned and if there is no such value None is returned.

For more information read RFC6901.

Examples

let data = json!({
    "x": {
        "y": ["z", "zz"]
    }
});

assert_eq!(data.pointer("/x/y/1").unwrap(), &json!("zz"));
assert_eq!(data.pointer("/a/b/c"), None);

Looks up a value by a JSON Pointer and returns a mutable reference to that value.

JSON Pointer defines a string syntax for identifying a specific value within a JavaScript Object Notation (JSON) document.

A Pointer is a Unicode string with the reference tokens separated by /. Inside tokens / is replaced by ~1 and ~ is replaced by ~0. The addressed value is returned and if there is no such value None is returned.

For more information read RFC6901.

Example of Use

extern crate serde_json;

use serde_json::Value;

fn main() {
    let s = r#"{"x": 1.0, "y": 2.0}"#;
    let mut value: Value = serde_json::from_str(s).unwrap();

    // Check value using read-only pointer
    assert_eq!(value.pointer("/x"), Some(&1.0.into()));
    // Change value with direct assignment
    *value.pointer_mut("/x").unwrap() = 1.5.into();
    // Check that new value was written
    assert_eq!(value.pointer("/x"), Some(&1.5.into()));

    // "Steal" ownership of a value. Can replace with any valid Value.
    let old_x = value.pointer_mut("/x").map(Value::take).unwrap();
    assert_eq!(old_x, 1.5);
    assert_eq!(value.pointer("/x").unwrap(), &Value::Null);
}

Takes the value out of the Value, leaving a Null in its place.

let mut v = json!({ "x": "y" });
assert_eq!(v["x"].take(), json!("y"));
assert_eq!(v, json!({ "x": null }));

Trait Implementations

impl<T> FromIterator<T> for Value where
    T: Into<Value>, 
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Convert an iteratable type to a Value

Examples

use serde_json::Value;

let v = std::iter::repeat(42).take(5);
let x: Value = v.collect();
use serde_json::Value;

let v: Vec<_> = vec!["lorem", "ipsum", "dolor"];
let x: Value = v.into_iter().collect();
use std::iter::FromIterator;
use serde_json::Value;

let x: Value = Value::from_iter(vec!["lorem", "ipsum", "dolor"]);

impl Display for Value
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Display a JSON value as a string.

let json = json!({ "city": "London", "street": "10 Downing Street" });

// Compact format:
//
// {"city":"London","street":"10 Downing Street"}
let compact = format!("{}", json);
assert_eq!(compact,
    "{\"city\":\"London\",\"street\":\"10 Downing Street\"}");

// Pretty format:
//
// {
//   "city": "London",
//   "street": "10 Downing Street"
// }
let pretty = format!("{:#}", json);
assert_eq!(pretty,
    "{\n  \"city\": \"London\",\n  \"street\": \"10 Downing Street\"\n}");

impl FromStr for Value
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The associated error which can be returned from parsing.

impl<I> IndexMut<I> for Value where
    I: Index
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Write into a serde_json::Value using the syntax value[0] = ... or value["k"] = ....

If the index is a number, the value must be an array of length bigger than the index. Indexing into a value that is not an array or an array that is too small will panic.

If the index is a string, the value must be an object or null which is treated like an empty object. If the key is not already present in the object, it will be inserted with a value of null. Indexing into a value that is neither an object nor null will panic.

Examples

let mut data = json!({ "x": 0 });

// replace an existing key
data["x"] = json!(1);

// insert a new key
data["y"] = json!([false, false, false]);

// replace an array value
data["y"][0] = json!(true);

// inserted a deeply nested key
data["a"]["b"]["c"]["d"] = json!(true);

println!("{}", data);

impl From<isize> for Value
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impl From<i8> for Value
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impl From<i16> for Value
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impl From<bool> for Value
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Convert boolean to Value

Examples

use serde_json::Value;

let b = false;
let x: Value = b.into();

impl From<f64> for Value
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Convert 64-bit floating point number to Value

Examples

use serde_json::Value;

let f: f64 = 13.37;
let x: Value = f.into();

impl From<u8> for Value
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impl From<usize> for Value
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impl From<Map<String, Value>> for Value
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Convert map (with string keys) to Value

Examples

use serde_json::{Map, Value};

let mut m = Map::new();
m.insert("Lorem".to_string(), "ipsum".into());
let x: Value = m.into();

impl From<u32> for Value
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impl<'a> From<&'a str> for Value
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Convert string slice to Value

Examples

use serde_json::Value;

let s: &str = "lorem";
let x: Value = s.into();

impl From<u64> for Value
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impl From<i64> for Value
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impl From<u16> for Value
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impl<'a> From<Cow<'a, str>> for Value
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Convert copy-on-write string to Value

Examples

use serde_json::Value;
use std::borrow::Cow;

let s: Cow<str> = Cow::Borrowed("lorem");
let x: Value = s.into();
use serde_json::Value;
use std::borrow::Cow;

let s: Cow<str> = Cow::Owned("lorem".to_string());
let x: Value = s.into();

impl From<String> for Value
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Convert String to Value

Examples

use serde_json::Value;

let s: String = "lorem".to_string();
let x: Value = s.into();

impl<T> From<Vec<T>> for Value where
    T: Into<Value>, 
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Convert a Vec to Value

Examples

use serde_json::Value;

let v = vec!["lorem", "ipsum", "dolor"];
let x: Value = v.into();

impl From<i32> for Value
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impl<'a, T> From<&'a [T]> for Value where
    T: Clone + Into<Value>, 
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Convert a slice to Value

Examples

use serde_json::Value;

let v: &[&str] = &["lorem", "ipsum", "dolor"];
let x: Value = v.into();

impl From<f32> for Value
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Convert 32-bit floating point number to Value

Examples

use serde_json::Value;

let f: f32 = 13.37;
let x: Value = f.into();

impl<'a> PartialEq<isize> for &'a mut Value
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This method tests for !=.

impl PartialEq<usize> for Value
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This method tests for !=.

impl<'a> PartialEq<u64> for &'a Value
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This method tests for !=.

impl<'a> PartialEq<i8> for &'a Value
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This method tests for !=.

impl<'a> PartialEq<f32> for &'a mut Value
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This method tests for !=.

impl<'a> PartialEq<i64> for &'a Value
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This method tests for !=.

impl PartialEq<Value> for Value
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impl<'a> PartialEq<u8> for &'a mut Value
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This method tests for !=.

impl PartialEq<isize> for Value
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This method tests for !=.

impl PartialEq<i64> for Value
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This method tests for !=.

impl<'a> PartialEq<u16> for &'a Value
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This method tests for !=.

impl<'a> PartialEq<usize> for &'a mut Value
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This method tests for !=.

impl<'a> PartialEq<i16> for &'a Value
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This method tests for !=.

impl<'a> PartialEq<&'a str> for Value
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This method tests for !=.

impl PartialEq<i32> for Value
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This method tests for !=.

impl<'a> PartialEq<i8> for &'a mut Value
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This method tests for !=.

impl<'a> PartialEq<u8> for &'a Value
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This method tests for !=.

impl PartialEq<String> for Value
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This method tests for !=.

impl PartialEq<f64> for Value
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This method tests for !=.

impl<'a> PartialEq<i64> for &'a mut Value
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This method tests for !=.

impl PartialEq<str> for Value
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This method tests for !=.

impl PartialEq<bool> for Value
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This method tests for !=.

impl PartialEq<i8> for Value
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This method tests for !=.

impl<'a> PartialEq<i16> for &'a mut Value
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This method tests for !=.

impl<'a> PartialEq<isize> for &'a Value
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This method tests for !=.

impl<'a> PartialEq<u32> for &'a mut Value
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This method tests for !=.

impl PartialEq<u8> for Value
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This method tests for !=.

impl<'a> PartialEq<bool> for &'a Value
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This method tests for !=.

impl<'a> PartialEq<i32> for &'a mut Value
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This method tests for !=.

impl<'a> PartialEq<f64> for &'a Value
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This method tests for !=.

impl<'a> PartialEq<u64> for &'a mut Value
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This method tests for !=.

impl PartialEq<u16> for Value
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This method tests for !=.

impl<'a> PartialEq<f32> for &'a Value
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This method tests for !=.

impl<'a> PartialEq<u32> for &'a Value
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This method tests for !=.

impl PartialEq<i16> for Value
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This method tests for !=.

impl<'a> PartialEq<f64> for &'a mut Value
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This method tests for !=.

impl<'a> PartialEq<usize> for &'a Value
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This method tests for !=.

impl PartialEq<f32> for Value
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This method tests for !=.

impl PartialEq<u64> for Value
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This method tests for !=.

impl<'a> PartialEq<i32> for &'a Value
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This method tests for !=.

impl<'a> PartialEq<u16> for &'a mut Value
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This method tests for !=.

impl<'a> PartialEq<bool> for &'a mut Value
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This method tests for !=.

impl PartialEq<u32> for Value
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This method tests for !=.

impl Clone for Value
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Performs copy-assignment from source. Read more

impl Default for Value
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The default value is Value::Null.

This is useful for handling omitted Value fields when deserializing.

Examples

use serde_json::Value;

#[derive(Deserialize)]
struct Settings {
    level: i32,
    #[serde(default)]
    extras: Value,
}

let data = r#" { "level": 42 } "#;
let s: Settings = serde_json::from_str(data)?;

assert_eq!(s.level, 42);
assert_eq!(s.extras, Value::Null);

impl Serialize for Value
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impl<'de> Deserialize<'de> for Value
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impl Debug for Value
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impl<'de> Deserializer<'de> for Value
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The error type that can be returned if some error occurs during deserialization. Read more

Determine whether Deserialize implementations should expect to deserialize their human-readable form. Read more

impl<'de> Deserializer<'de> for &'de Value
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The error type that can be returned if some error occurs during deserialization. Read more

Determine whether Deserialize implementations should expect to deserialize their human-readable form. Read more

impl<I> Index<I> for Value where
    I: Index
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The returned type after indexing.

Index into a serde_json::Value using the syntax value[0] or value["k"].

Returns Value::Null if the type of self does not match the type of the index, for example if the index is a string and self is an array or a number. Also returns Value::Null if the given key does not exist in the map or the given index is not within the bounds of the array.

For retrieving deeply nested values, you should have a look at the Value::pointer method.

Examples

let data = json!({
    "x": {
        "y": ["z", "zz"]
    }
});

assert_eq!(data["x"]["y"], json!(["z", "zz"]));
assert_eq!(data["x"]["y"][0], json!("z"));

assert_eq!(data["a"], json!(null)); // returns null for undefined values
assert_eq!(data["a"]["b"], json!(null)); // does not panic

Auto Trait Implementations

impl Send for Value

impl Sync for Value

Blanket Implementations

impl<T> From for T
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impl<T, U> Into for T where
    U: From<T>, 
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impl<T> ToString for T where
    T: Display + ?Sized
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impl<T> ToOwned for T where
    T: Clone
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impl<T, U> TryFrom for T where
    T: From<U>, 
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🔬 This is a nightly-only experimental API. (try_from)

The type returned in the event of a conversion error.

impl<T> Borrow for T where
    T: ?Sized
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impl<T, U> TryInto for T where
    U: TryFrom<T>, 
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🔬 This is a nightly-only experimental API. (try_from)

The type returned in the event of a conversion error.

impl<T> BorrowMut for T where
    T: ?Sized
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impl<T> Any for T where
    T: 'static + ?Sized
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impl<T> DeserializeOwned for T where
    T: Deserialize<'de>, 
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