Struct Map

pub struct Map<K, V> { /* private fields */ }

Represents a JSON key/value type.

Implementations

impl Map<String, Value>

pub fn new() -> Self

Makes a new empty Map.

pub fn with_capacity(capacity: usize) -> Self

Makes a new empty Map with the given initial capacity.

pub fn clear(&mut self)

Clears the map, removing all values.

pub fn get<Q>(&self, key: &Q) -> Option<&Value>

where String: Borrow<Q>, Q: ?Sized + Ord + Eq + Hash,

Returns a reference to the value corresponding to the key.

The key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

pub fn contains_key<Q>(&self, key: &Q) -> bool

where String: Borrow<Q>, Q: ?Sized + Ord + Eq + Hash,

Returns true if the map contains a value for the specified key.

The key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

pub fn get_mut<Q>(&mut self, key: &Q) -> Option<&mut Value>

where String: Borrow<Q>, Q: ?Sized + Ord + Eq + Hash,

Returns a mutable reference to the value corresponding to the key.

The key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

pub fn get_key_value<Q>(&self, key: &Q) -> Option<(&String, &Value)>

where String: Borrow<Q>, Q: ?Sized + Ord + Eq + Hash,

Returns the key-value pair matching the given key.

The key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

pub fn insert(&mut self, k: String, v: Value) -> Option<Value>

Inserts a key-value pair into the map.

If the map did not have this key present, None is returned.

If the map did have this key present, the value is updated, and the old value is returned.

pub fn remove<Q>(&mut self, key: &Q) -> Option<Value>

where String: Borrow<Q>, Q: ?Sized + Ord + Eq + Hash,

Removes a key from the map, returning the value at the key if the key was previously in the map.

The key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

If serde_json’s “preserve_order” is enabled, .remove(key) is equivalent to [.swap_remove(key)][Self::swap_remove], replacing this entry’s position with the last element. If you need to preserve the relative order of the keys in the map, use [.shift_remove(key)][Self::shift_remove] instead.

pub fn remove_entry<Q>(&mut self, key: &Q) -> Option<(String, Value)>

where String: Borrow<Q>, Q: ?Sized + Ord + Eq + Hash,

Removes a key from the map, returning the stored key and value if the key was previously in the map.

The key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

If serde_json’s “preserve_order” is enabled, .remove_entry(key) is equivalent to [.swap_remove_entry(key)][Self::swap_remove_entry], replacing this entry’s position with the last element. If you need to preserve the relative order of the keys in the map, use [.shift_remove_entry(key)][Self::shift_remove_entry] instead.

pub fn append(&mut self, other: &mut Self)

Moves all elements from other into self, leaving other empty.

pub fn entry<S>(&mut self, key: S) -> Entry<'_>

where S: Into<String>,

Gets the given key’s corresponding entry in the map for in-place manipulation.

pub fn len(&self) -> usize

Returns the number of elements in the map.

pub fn is_empty(&self) -> bool

Returns true if the map contains no elements.

pub fn iter(&self) -> Iter<'_>

Gets an iterator over the entries of the map.

pub fn iter_mut(&mut self) -> IterMut<'_>

Gets a mutable iterator over the entries of the map.

pub fn keys(&self) -> Keys<'_>

Gets an iterator over the keys of the map.

pub fn values(&self) -> Values<'_>

Gets an iterator over the values of the map.

pub fn values_mut(&mut self) -> ValuesMut<'_>

Gets an iterator over mutable values of the map.

pub fn retain<F>(&mut self, f: F)

where F: FnMut(&String, &mut Value) -> bool,

Retains only the elements specified by the predicate.

In other words, remove all pairs (k, v) such that f(&k, &mut v) returns false.

pub fn sort_keys(&mut self)

Sorts this map’s entries in-place using str’s usual ordering.

If serde_json’s “preserve_order” feature is not enabled, this method does no work because all JSON maps are always kept in a sorted state.

If serde_json’s “preserve_order” feature is enabled, this method destroys the original source order or insertion order of this map in favor of an alphanumerical order that matches how a BTreeMap with the same contents would be ordered. This takes O(n log n + c) time where n is the length of the map and c is the capacity.

Other maps nested within the values of this map are not sorted. If you need the entire data structure to be sorted at all levels, you must also call map.values_mut().for_each(Value::sort_all_objects).

Trait Implementations

impl Clone for Map<String, Value>

fn clone(&self) -> Self

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Map<String, Value>

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

Formats the value using the given formatter.

impl Default for Map<String, Value>

fn default() -> Self

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Map<String, Value>

fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<'de> Deserializer<'de> for &'de Map<String, 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, Self::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_enum<V>( self, _name: &'static str, _variants: &'static [&'static str], visitor: V, ) -> Result<V::Value, Self::Error>

where V: Visitor<'de>,

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

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 deserialize_bool<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a bool value.

fn deserialize_i8<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting an i64 value.

fn deserialize_i128<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting an i128 value.

fn deserialize_u8<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a u64 value.

fn deserialize_u128<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting an u128 value.

fn deserialize_f32<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a f64 value.

fn deserialize_char<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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_option<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting an optional value.

fn deserialize_unit<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

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

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

where V: Visitor<'de>,

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

fn deserialize_seq<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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 is_human_readable(&self) -> bool

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

impl<'de> Deserializer<'de> for Map<String, 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, Self::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_enum<V>( self, _name: &'static str, _variants: &'static [&'static str], visitor: V, ) -> Result<V::Value, Self::Error>

where V: Visitor<'de>,

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

fn deserialize_ignored_any<V>(self, visitor: V) -> Result<V::Value, Self::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 deserialize_bool<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a bool value.

fn deserialize_i8<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting an i64 value.

fn deserialize_i128<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting an i128 value.

fn deserialize_u8<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a u64 value.

fn deserialize_u128<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting an u128 value.

fn deserialize_f32<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a f64 value.

fn deserialize_char<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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_option<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting an optional value.

fn deserialize_unit<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

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

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

where V: Visitor<'de>,

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

fn deserialize_seq<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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, <Self as Deserializer<'de>>::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 is_human_readable(&self) -> bool

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

impl Extend<(String, Value)> for Map<String, Value>

fn extend<T>(&mut self, iter: T)

where T: IntoIterator<Item = (String, Value)>,

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

🔬This is a nightly-only experimental API. (extend_one)

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

🔬This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements.

impl From<Map<String, Value>> for Value

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

Convert map (with string keys) to Value::Object.

Examples

use serde_json::{Map, Value};

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

impl FromIterator<(String, Value)> for Map<String, Value>

fn from_iter<T>(iter: T) -> Self

where T: IntoIterator<Item = (String, Value)>,

Creates a value from an iterator.

impl Hash for Map<String, Value>

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<Q> Index<&Q> for Map<String, Value>

where String: Borrow<Q>, Q: ?Sized + Ord + Eq + Hash,

Access an element of this map. Panics if the given key is not present in the map.

match val {
    Value::String(s) => Some(s.as_str()),
    Value::Array(arr) => arr[0].as_str(),
    Value::Object(map) => map["type"].as_str(),
    _ => None,
}

type Output = Value

The returned type after indexing.

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

Performs the indexing (container[index]) operation.

impl<Q> IndexMut<&Q> for Map<String, Value>

where String: Borrow<Q>, Q: ?Sized + Ord + Eq + Hash,

Mutably access an element of this map. Panics if the given key is not present in the map.

map["key"] = json!("value");

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

Performs the mutable indexing (container[index]) operation.

impl<'de> IntoDeserializer<'de, Error> for &'de Map<String, Value>

type Deserializer = &'de Map<String, Value>

The type of the deserializer being converted into.

fn into_deserializer(self) -> Self::Deserializer

Convert this value into a deserializer.

impl<'de> IntoDeserializer<'de, Error> for Map<String, Value>

type Deserializer = Map<String, Value>

The type of the deserializer being converted into.

fn into_deserializer(self) -> Self::Deserializer

Convert this value into a deserializer.

impl<'a> IntoIterator for &'a Map<String, Value>

type Item = (&'a String, &'a Value)

The type of the elements being iterated over.

type IntoIter = Iter<'a>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<'a> IntoIterator for &'a mut Map<String, Value>

type Item = (&'a String, &'a mut Value)

The type of the elements being iterated over.

type IntoIter = IterMut<'a>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl IntoIterator for Map<String, Value>

type Item = (String, Value)

The type of the elements being iterated over.

type IntoIter = IntoIter

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl PartialEq for Map<String, Value>

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for Map<String, 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 Map<String, Value>