Enum serde_json::value::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

Null

Represents a JSON null value.

let v = json!(null);

Bool(bool)

Represents a JSON boolean.

let v = json!(true);

Number(Number)

Represents a JSON number, whether integer or floating point.

let v = json!(12.5);

String(String)

Represents a JSON string.

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

Array(Vec<Value>)

Represents a JSON array.

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

Object(Map<String, Value>)

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" });

Implementations

impl Value

pub fn get<I: Index>(&self, index: I) -> Option<&Value>

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));

pub fn get_mut<I: Index>(&mut self, index: I) -> Option<&mut Value>

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");

pub fn is_object(&self) -> bool

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());

pub fn as_object(&self) -> Option<&Map<String, Value>>

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);

pub fn as_object_mut(&mut self) -> Option<&mut Map<String, Value>>

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": {} }));

pub fn is_array(&self) -> bool

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());

pub fn as_array(&self) -> Option<&Vec<Value>>

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);

pub fn as_array_mut(&mut self) -> Option<&mut Vec<Value>>

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": [] }));

pub fn is_string(&self) -> bool

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());

pub fn as_str(&self) -> Option<&str>

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());

pub fn is_number(&self) -> bool

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());

pub fn is_i64(&self) -> bool

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());

pub fn is_u64(&self) -> bool

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());

pub fn is_f64(&self) -> bool

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());

pub fn as_i64(&self) -> Option<i64>

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);

pub fn as_u64(&self) -> Option<u64>

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);

pub fn as_f64(&self) -> Option<f64>

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));

pub fn is_boolean(&self) -> bool

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());

pub fn as_bool(&self) -> Option<bool>

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);

pub fn is_null(&self) -> bool

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());

pub fn as_null(&self) -> Option<()>

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);

pub fn pointer(&self, pointer: &str) -> Option<&Value>

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);

pub fn pointer_mut(&mut self, pointer: &str) -> Option<&mut Value>

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

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()));
    // Or change the value only if it exists
    value.pointer_mut("/x").map(|v| *v = 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);
}

pub fn take(&mut self) -> Value

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 Clone for Value

fn clone(&self) -> Value

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Value

fn fmt(&self, formatter: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Value

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);

fn default() -> Value

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Value

fn deserialize<D>(deserializer: D) -> Result<Value, D::Error> where
    D: Deserializer<'de>, 

Deserialize this value from the given Serde deserializer.

impl<'de> Deserializer<'de> for Value

type Error = Error

The error type that can be returned if some error occurs during deserialization.

fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Require the Deserializer to figure out how to drive the visitor based on what data type is in the input.

fn deserialize_i8<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting an i8 value.

fn deserialize_i16<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting an i16 value.

fn deserialize_i32<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting an i32 value.

fn deserialize_i64<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting an i64 value.

fn deserialize_u8<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a u8 value.

fn deserialize_u16<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a u16 value.

fn deserialize_u32<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a u32 value.

fn deserialize_u64<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a u64 value.

fn deserialize_f32<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a f32 value.

fn deserialize_f64<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a f64 value.

fn deserialize_i128<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting an i128 value.

fn deserialize_u128<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting an u128 value.

fn deserialize_option<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting an optional value.

fn deserialize_enum<V>(
    self,
    _name: &str,
    _variants: &'static [&'static str],
    visitor: V
) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting an enum value with a particular name and possible variants.

fn deserialize_newtype_struct<V>(
    self,
    name: &'static str,
    visitor: V
) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a newtype struct with a particular name.

fn deserialize_bool<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a bool value.

fn deserialize_char<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a char value.

fn deserialize_str<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a string value and does not benefit from taking ownership of buffered data owned by the Deserializer.

fn deserialize_string<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a string value and would benefit from taking ownership of buffered data owned by the Deserializer.

fn deserialize_bytes<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a byte array and does not benefit from taking ownership of buffered data owned by the Deserializer.

fn deserialize_byte_buf<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a byte array and would benefit from taking ownership of buffered data owned by the Deserializer.

fn deserialize_unit<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a unit value.

fn deserialize_unit_struct<V>(
    self,
    _name: &'static str,
    visitor: V
) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a unit struct with a particular name.

fn deserialize_seq<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a sequence of values.

fn deserialize_tuple<V>(
    self,
    _len: usize,
    visitor: V
) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a sequence of values and knows how many values there are without looking at the serialized data.

fn deserialize_tuple_struct<V>(
    self,
    _name: &'static str,
    _len: usize,
    visitor: V
) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a tuple struct with a particular name and number of fields.

fn deserialize_map<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a map of key-value pairs.

fn deserialize_struct<V>(
    self,
    _name: &'static str,
    _fields: &'static [&'static str],
    visitor: V
) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a struct with a particular name and fields.

fn deserialize_identifier<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting the name of a struct field or the discriminant of an enum variant.

fn deserialize_ignored_any<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type needs to deserialize a value whose type doesn’t matter because it is ignored.

fn is_human_readable(&self) -> bool

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

impl<'de> Deserializer<'de> for &'de Value

type Error = Error

The error type that can be returned if some error occurs during deserialization.

fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Require the Deserializer to figure out how to drive the visitor based on what data type is in the input.

fn deserialize_i8<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting an i8 value.

fn deserialize_i16<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting an i16 value.

fn deserialize_i32<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting an i32 value.

fn deserialize_i64<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting an i64 value.

fn deserialize_u8<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a u8 value.

fn deserialize_u16<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a u16 value.

fn deserialize_u32<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a u32 value.

fn deserialize_u64<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a u64 value.

fn deserialize_f32<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a f32 value.

fn deserialize_f64<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a f64 value.

fn deserialize_i128<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting an i128 value.

fn deserialize_u128<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting an u128 value.

fn deserialize_option<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting an optional value.

fn deserialize_enum<V>(
    self,
    _name: &str,
    _variants: &'static [&'static str],
    visitor: V
) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting an enum value with a particular name and possible variants.

fn deserialize_newtype_struct<V>(
    self,
    name: &'static str,
    visitor: V
) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a newtype struct with a particular name.

fn deserialize_bool<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a bool value.

fn deserialize_char<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a char value.

fn deserialize_str<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a string value and does not benefit from taking ownership of buffered data owned by the Deserializer.

fn deserialize_string<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a string value and would benefit from taking ownership of buffered data owned by the Deserializer.

fn deserialize_bytes<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a byte array and does not benefit from taking ownership of buffered data owned by the Deserializer.

fn deserialize_byte_buf<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a byte array and would benefit from taking ownership of buffered data owned by the Deserializer.

fn deserialize_unit<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a unit value.

fn deserialize_unit_struct<V>(
    self,
    _name: &'static str,
    visitor: V
) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a unit struct with a particular name.

fn deserialize_seq<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a sequence of values.

fn deserialize_tuple<V>(
    self,
    _len: usize,
    visitor: V
) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a sequence of values and knows how many values there are without looking at the serialized data.

fn deserialize_tuple_struct<V>(
    self,
    _name: &'static str,
    _len: usize,
    visitor: V
) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a tuple struct with a particular name and number of fields.

fn deserialize_map<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a map of key-value pairs.

fn deserialize_struct<V>(
    self,
    _name: &'static str,
    _fields: &'static [&'static str],
    visitor: V
) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting a struct with a particular name and fields.

fn deserialize_identifier<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type is expecting the name of a struct field or the discriminant of an enum variant.

fn deserialize_ignored_any<V>(self, visitor: V) -> Result<V::Value, Error> where
    V: Visitor<'de>, 

Hint that the Deserialize type needs to deserialize a value whose type doesn’t matter because it is ignored.

fn is_human_readable(&self) -> bool

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

impl Display for Value

fn fmt(&self, f: &mut Formatter<'_>) -> Result

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<'a, T: Clone + Into<Value>> From<&'a [T]> for Value

fn from(f: &'a [T]) -> Self

Convert a slice to Value

Examples

use serde_json::Value;

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

impl<'a> From<&'a str> for Value

fn from(f: &str) -> Self

Convert string slice to Value

Examples

use serde_json::Value;

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

impl From<()> for Value

fn from((): ()) -> Self

Convert () to Value

Examples

use serde_json::Value;

let u = ();
let x: Value = u.into();

impl<'a> From<Cow<'a, str>> for Value

fn from(f: Cow<'a, str>) -> Self

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<Map<String, Value>> for Value

fn from(f: Map<String, Value>) -> Self

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<Number> for Value

fn from(f: Number) -> Self

Convert Number to Value

Examples

use serde_json::{Number, Value};

let n = Number::from(7);
let x: Value = n.into();

impl From<String> for Value

fn from(f: String) -> Self

Convert String to Value

Examples

use serde_json::Value;

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

impl<T: Into<Value>> From<Vec<T, Global>> for Value

fn from(f: Vec<T>) -> Self

Convert a Vec to Value

Examples

use serde_json::Value;

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

impl From<bool> for Value

fn from(f: bool) -> Self

Convert boolean to Value

Examples

use serde_json::Value;

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

impl From<f32> for Value

fn from(f: f32) -> Self

Convert 32-bit floating point number to Value

Examples

use serde_json::Value;

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

impl From<f64> for Value

fn from(f: f64) -> Self

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<i16> for Value

fn from(n: i16) -> Self

Performs the conversion.

impl From<i32> for Value

fn from(n: i32) -> Self

Performs the conversion.

impl From<i64> for Value

fn from(n: i64) -> Self

Performs the conversion.

impl From<i8> for Value

fn from(n: i8) -> Self

Performs the conversion.

impl From<isize> for Value

fn from(n: isize) -> Self

Performs the conversion.

impl From<u16> for Value

fn from(n: u16) -> Self

Performs the conversion.

impl From<u32> for Value

fn from(n: u32) -> Self

Performs the conversion.

impl From<u64> for Value

fn from(n: u64) -> Self

Performs the conversion.

impl From<u8> for Value

fn from(n: u8) -> Self

Performs the conversion.

impl From<usize> for Value

fn from(n: usize) -> Self

Performs the conversion.

impl<K: Into<String>, V: Into<Value>> FromIterator<(K, V)> for Value

fn from_iter<I: IntoIterator<Item = (K, V)>>(iter: I) -> Self

Convert an iteratable type to a Value

Examples

use serde_json::Value;

let v: Vec<_> = vec![("lorem", 40), ("ipsum", 2)];
let x: Value = v.into_iter().collect();

impl<T: Into<Value>> FromIterator<T> for Value

fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Self

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 FromStr for Value

type Err = Error

The associated error which can be returned from parsing.

fn from_str(s: &str) -> Result<Value, Error>

Parses a string s to return a value of this type.

impl<I> Index<I> for Value where
    I: Index, 

fn index(&self, index: I) -> &Value

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

type Output = Value

The returned type after indexing.

impl<I> IndexMut<I> for Value where
    I: Index, 

fn index_mut(&mut self, index: I) -> &mut Value

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<'de> IntoDeserializer<'de, Error> for Value

type Deserializer = Self

The type of the deserializer being converted into.

fn into_deserializer(self) -> Self::Deserializer

Convert this value into a deserializer.

impl<'a> PartialEq<&'a str> for Value

fn eq(&self, other: &&str) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<String> for Value

fn eq(&self, other: &String) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<Value> for Value

fn eq(&self, other: &Value) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Value) -> bool

This method tests for !=.

impl PartialEq<Value> for str

fn eq(&self, other: &Value) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<Value> for u16

fn eq(&self, other: &Value) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<Value> for u32

fn eq(&self, other: &Value) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<Value> for u64

fn eq(&self, other: &Value) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<Value> for usize

fn eq(&self, other: &Value) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<Value> for f32

fn eq(&self, other: &Value) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<Value> for f64

fn eq(&self, other: &Value) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<Value> for bool

fn eq(&self, other: &Value) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<Value> for &'a str

fn eq(&self, other: &Value) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<Value> for String

fn eq(&self, other: &Value) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<Value> for i8

fn eq(&self, other: &Value) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<Value> for i16

fn eq(&self, other: &Value) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<Value> for i32

fn eq(&self, other: &Value) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<Value> for i64

fn eq(&self, other: &Value) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<Value> for isize

fn eq(&self, other: &Value) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<Value> for u8

fn eq(&self, other: &Value) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<bool> for Value

fn eq(&self, other: &bool) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<bool> for &'a Value

fn eq(&self, other: &bool) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<bool> for &'a mut Value

fn eq(&self, other: &bool) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<f32> for Value

fn eq(&self, other: &f32) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<f32> for &'a Value

fn eq(&self, other: &f32) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<f32> for &'a mut Value

fn eq(&self, other: &f32) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<f64> for Value

fn eq(&self, other: &f64) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<f64> for &'a Value

fn eq(&self, other: &f64) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<f64> for &'a mut Value

fn eq(&self, other: &f64) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<i16> for Value

fn eq(&self, other: &i16) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<i16> for &'a Value

fn eq(&self, other: &i16) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<i16> for &'a mut Value

fn eq(&self, other: &i16) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<i32> for Value

fn eq(&self, other: &i32) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<i32> for &'a Value

fn eq(&self, other: &i32) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<i32> for &'a mut Value

fn eq(&self, other: &i32) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<i64> for Value

fn eq(&self, other: &i64) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<i64> for &'a Value

fn eq(&self, other: &i64) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<i64> for &'a mut Value

fn eq(&self, other: &i64) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<i8> for Value

fn eq(&self, other: &i8) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<i8> for &'a Value

fn eq(&self, other: &i8) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<i8> for &'a mut Value

fn eq(&self, other: &i8) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<isize> for Value

fn eq(&self, other: &isize) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<isize> for &'a Value

fn eq(&self, other: &isize) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<isize> for &'a mut Value

fn eq(&self, other: &isize) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<str> for Value

fn eq(&self, other: &str) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<u16> for Value

fn eq(&self, other: &u16) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<u16> for &'a Value

fn eq(&self, other: &u16) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<u16> for &'a mut Value

fn eq(&self, other: &u16) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<u32> for Value

fn eq(&self, other: &u32) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<u32> for &'a Value

fn eq(&self, other: &u32) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<u32> for &'a mut Value

fn eq(&self, other: &u32) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<u64> for Value

fn eq(&self, other: &u64) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<u64> for &'a Value

fn eq(&self, other: &u64) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<u64> for &'a mut Value

fn eq(&self, other: &u64) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<u8> for Value

fn eq(&self, other: &u8) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<u8> for &'a Value

fn eq(&self, other: &u8) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<u8> for &'a mut Value

fn eq(&self, other: &u8) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<usize> for Value

fn eq(&self, other: &usize) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<usize> for &'a Value

fn eq(&self, other: &usize) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a> PartialEq<usize> for &'a mut Value

fn eq(&self, other: &usize) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl Serialize for Value

fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> where
    S: Serializer, 

Serialize this value into the given Serde serializer.

impl Eq for Value

impl StructuralEq for Value

impl StructuralPartialEq for Value