# Enum serde_json::map::Entry

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

Expand description

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

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### impl<'a> Entry<'a>

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#### pub fn key(&self) -> &String

Returns a reference to this entry’s key.

##### Examples

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

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

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);

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

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());

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

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>

### impl<'a> Send for Entry<'a>

### impl<'a> Sync for Entry<'a>

### impl<'a> Unpin for Entry<'a>

### impl<'a> !UnwindSafe for Entry<'a>

## Blanket Implementations

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### impl<T> Any for T where
T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

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

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### impl<T> Borrow<T> for T where
T: ?Sized,

const: unstable · source

#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more

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### impl<T> BorrowMut<T> for T where
T: ?Sized,

const: unstable · source

#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more

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### impl<T> From<T> for T

const: unstable · source

#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T, U> Into<U> for T where
U: From<T>,

const: unstable · source

#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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### impl<T, U> TryFrom<U> for T where
U: Into<T>,

#### type Error = Infallible

The type returned in the event of a conversion error.

const: unstable · source

#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.

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### impl<T, U> TryInto<U> for T where
U: TryFrom<T>,

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

The type returned in the event of a conversion error.

const: unstable · source

#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.