# serde_json::map::Entry - Rust
API documentation for the Rust `Entry` enum in crate `serde_json`.
Keywords: rust, rustlang, rust-lang, Entry

# Enum serde_json::map::Entry [−] [src]

    pub enum Entry<'a> {
        Vacant(VacantEntry<'a>),
        Occupied(OccupiedEntry<'a>),
    }

A view into a single entry in a map, which may either be vacant or occupied. This enum is constructed from the `entry` method on `Map`.

## Variants

`Vacant(VacantEntry<'a>)`

A vacant Entry.

`Occupied(OccupiedEntry<'a>)`

An occupied Entry.

## Implementations

### `impl<'a> Entry<'a>` [src]

#### `pub fn key(&self) -> &String` [src]

Returns a reference to this entry's key.

# Examples

    let mut map = serde_json::Map::new();
    assert_eq!(map.entry("serde").key(), &"serde");

#### `pub fn or_insert(self, default: Value) -> &'a mut Value` [src]

Ensures a value is in the entry by inserting the default if empty, and returns a mutable reference to the value in the entry.

# Examples

    let mut map = serde_json::Map::new();
    map.entry("serde").or_insert(json!(12));

    assert_eq!(map["serde"], 12);

#### `pub fn or_insert_with<F>(self, default: F) -> &'a mut Value where
F: FnOnce() -> Value,` [src]

Ensures a value is in the entry by inserting the result of the default function if empty, and returns a mutable reference to the value in the entry.

# Examples

    let mut map = serde_json::Map::new();
    map.entry("serde").or_insert_with(|| json!("hoho"));

    assert_eq!(map["serde"], "hoho".to_owned());

#### `pub fn and_modify<F>(self, f: F) -> Self where
F: FnOnce(&mut Value),` [src]

Provides in-place mutable access to an occupied entry before any potential inserts into the map.

# Examples

    let mut map = serde_json::Map::new();
    map.entry("serde")
        .and_modify(|e| *e = json!("rust"))
        .or_insert(json!("cpp"));

    assert_eq!(map["serde"], "cpp");

    map.entry("serde")
        .and_modify(|e| *e = json!("rust"))
        .or_insert(json!("cpp"));

    assert_eq!(map["serde"], "rust");

## Auto Trait Implementations

### `impl<'a> RefUnwindSafe for Entry<'a>` [src]

### `impl<'a> Send for Entry<'a>` [src]

### `impl<'a> Sync for Entry<'a>` [src]

### `impl<'a> Unpin for Entry<'a>` [src]

### `impl<'a> !UnwindSafe for Entry<'a>` [src]

## Blanket Implementations

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `pub fn type_id(&self) -> TypeId` [src]

Gets the `TypeId` of `self`. Read more

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow(&self) -> &Tⓘ

### Notable traits for &'_ mut R

`impl<'_, R> Read for &'_ mut R where
R: Read + ?Sized, impl<'_, W> Write for &'_ mut W where
W: Write + ?Sized, impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;`
` [src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow_mut(&mut self) -> &mut Tⓘ

### Notable traits for &'_ mut R

`impl<'_, R> Read for &'_ mut R where
R: Read + ?Sized, impl<'_, W> Write for &'_ mut W where
W: Write + ?Sized, impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;`
` [src]

Mutably borrows from an owned value. Read more

### `impl<T> From<T> for T` [src]

#### `pub fn from(t: T) -> T` [src]

Performs the conversion.

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `pub fn into(self) -> U` [src]

Performs the conversion.

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

#### `pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>` [src]

Performs the conversion.

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

#### `type Error = <U as TryFrom<T>>::Error`

The type returned in the event of a conversion error.

#### `pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>` [src]

Performs the conversion.