Enum juniper::Nullable

pub enum Nullable<T> {
    ImplicitNull,
    ExplicitNull,
    Some(T),
}

Nullable can be used in situations where you need to distinguish between an implicitly and explicitly null input value.

The GraphQL spec states that these two field calls are similar, but are not identical:

{
  field(arg: null)
  field
}

The first has explicitly provided null to the argument “arg”, while the second has implicitly not provided a value to the argument “arg”. These two forms may be interpreted differently. For example, a mutation representing deleting a field vs not altering a field, respectively.

In cases where you do not need to be able to distinguish between the two types of null, you should simply use Option<T>.

Variants

ImplicitNull

No value

ExplicitNull

No value, explicitly specified to be null

Some(T)

Some value T

Implementations

impl<T> Nullable<T>

pub fn is_explicit_null(&self) -> bool

Returns true if the nullable is a ExplicitNull value.

pub fn is_implicit_null(&self) -> bool

Returns true if the nullable is a ImplicitNull value.

pub fn is_some(&self) -> bool

Returns true if the nullable is a Some value.

pub fn is_null(&self) -> bool

Returns true if the nullable is not a Some value.

pub fn as_mut(&mut self) -> Nullable<&mut T>

Converts from &mut Nullable<T> to Nullable<&mut T>.

pub fn expect(self, msg: &str) -> T

Returns the contained Some value, consuming the self value.

Panics

Panics if the value is not a Some with a custom panic message provided by msg.

pub fn unwrap_or(self, default: T) -> T

Returns the contained Some value or a provided default.

pub fn unwrap_or_else<F: FnOnce() -> T>(self, f: F) -> T

Returns the contained Some value or computes it from a closure.

pub fn map<U, F: FnOnce(T) -> U>(self, f: F) -> Nullable<U>

Maps a Nullable<T> to Nullable<U> by applying a function to a contained value.

pub fn map_or<U, F: FnOnce(T) -> U>(self, default: U, f: F) -> U

Applies a function to the contained value (if any), or returns the provided default (if not).

pub fn map_or_else<U, D: FnOnce() -> U, F: FnOnce(T) -> U>(
    self,
    default: D,
    f: F
) -> U

Applies a function to the contained value (if any), or computes a default (if not).

pub fn ok_or<E>(self, err: E) -> Result<T, E>

Transforms the Nullable<T> into a Result<T, E>, mapping Some(v) to Ok(v) and ImplicitNull or ExplicitNull to Err(err).

pub fn ok_or_else<E, F: FnOnce() -> E>(self, err: F) -> Result<T, E>

Transforms the Nullable<T> into a Result<T, E>, mapping Some(v) to Ok(v) and ImplicitNull or ExplicitNull to Err(err()).

pub fn or(self, b: Self) -> Self

Returns the nullable if it contains a value, otherwise returns b.

pub fn or_else<F: FnOnce() -> Nullable<T>>(self, f: F) -> Nullable<T>

Returns the nullable if it contains a value, otherwise calls f and returns the result.

pub fn replace(&mut self, value: T) -> Self

Replaces the actual value in the nullable by the value given in parameter, returning the old value if present, leaving a Some in its place without deinitializing either one.

pub fn some(self) -> Option<T>

Converts from Nullable<T> to Option<T>.

pub fn explicit(self) -> Option<Option<T>>

Converts from Nullable<T> to Option<Option<T>>, mapping Some(v) to Some(Some(v)), ExplicitNull to Some(None), and ImplicitNull to None.

impl<T: Copy, '_> Nullable<&'_ T>

pub fn copied(self) -> Nullable<T>

Maps a Nullable<&T> to a Nullable<T> by copying the contents of the nullable.

impl<T: Copy, '_> Nullable<&'_ mut T>

pub fn copied(self) -> Nullable<T>

Maps a Nullable<&mut T> to a Nullable<T> by copying the contents of the nullable.

impl<T: Clone, '_> Nullable<&'_ T>

pub fn cloned(self) -> Nullable<T>

Maps a Nullable<&T> to a Nullable<T> by cloning the contents of the nullable.

impl<T: Clone, '_> Nullable<&'_ mut T>

pub fn cloned(self) -> Nullable<T>

Maps a Nullable<&mut T> to a Nullable<T> by cloning the contents of the nullable.

Trait Implementations

impl<T: Clone> Clone for Nullable<T>

pub fn clone(&self) -> Nullable<T>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T: Copy> Copy for Nullable<T>

impl<T: Debug> Debug for Nullable<T>

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

Formats the value using the given formatter.

impl<T> Default for Nullable<T>

pub fn default() -> Self

Returns the "default value" for a type.

impl<T: Eq> Eq for Nullable<T>

impl<S, T> FromInputValue<S> for Nullable<T> where
    T: FromInputValue<S>,
    S: ScalarValue, 

pub fn from_input_value(v: &InputValue<S>) -> Option<Nullable<T>>

Performs the conversion.

pub fn from_implicit_null() -> Self

Performs the conversion from an absent value (e.g. to distinguish between implicit and explicit null). The default implementation just uses from_input_value as if an explicit null were provided. This conversion must not fail.

impl<S, T> GraphQLType<S> for Nullable<T> where
    T: GraphQLType<S>,
    S: ScalarValue, 

pub fn name(_: &Self::TypeInfo) -> Option<&'static str>

Returns name of this GraphQLType to expose.

pub fn meta<'r>(
    info: &Self::TypeInfo,
    registry: &mut Registry<'r, S>
) -> MetaType<'r, S> where
    S: 'r, 

Returns MetaType representing this GraphQLType.

impl<S, T> GraphQLValue<S> for Nullable<T> where
    S: ScalarValue,
    T: GraphQLValue<S>, 

type Context = T::Context

Context type for this GraphQLValue.

type TypeInfo = T::TypeInfo

Type that may carry additional schema information for this GraphQLValue.

pub fn type_name(&self, _: &Self::TypeInfo) -> Option<&'static str>

Returns name of the GraphQLType exposed by this GraphQLValue.

pub fn resolve(
    &self,
    info: &Self::TypeInfo,
    _: Option<&[Selection<'_, S>]>,
    executor: &Executor<'_, '_, Self::Context, S>
) -> ExecutionResult<S>

Resolves the provided selection_set against this GraphQLValue.

pub fn resolve_field(
    &self,
    _info: &Self::TypeInfo,
    _field_name: &str,
    _arguments: &Arguments<'_, S>,
    _executor: &Executor<'_, '_, Self::Context, S>
) -> ExecutionResult<S>

Resolves the value of a single field on this GraphQLValue.

pub fn resolve_into_type(
    &self,
    info: &Self::TypeInfo,
    type_name: &str,
    selection_set: Option<&[Selection<'_, S>]>,
    executor: &Executor<'_, '_, Self::Context, S>
) -> ExecutionResult<S>

Resolves this GraphQLValue (being an interface or an union) into a concrete downstream object type.

pub fn concrete_type_name(
    &self,
    context: &Self::Context,
    info: &Self::TypeInfo
) -> String

Returns the concrete GraphQLType name for this GraphQLValue being an interface, an union or an object.

impl<S, T> GraphQLValueAsync<S> for Nullable<T> where
    T: GraphQLValueAsync<S>,
    T::TypeInfo: Sync,
    T::Context: Sync,
    S: ScalarValue + Send + Sync, 

pub fn resolve_async<'a>(
    &'a self,
    info: &'a Self::TypeInfo,
    _: Option<&'a [Selection<'_, S>]>,
    executor: &'a Executor<'_, '_, Self::Context, S>
) -> BoxFuture<'a, ExecutionResult<S>>

Resolves the provided selection_set against this GraphQLValueAsync.

pub fn resolve_field_async<'a>(
    &'a self,
    _info: &'a Self::TypeInfo,
    _field_name: &'a str,
    _arguments: &'a Arguments<'_, S>,
    _executor: &'a Executor<'_, '_, Self::Context, S>
) -> BoxFuture<'a, ExecutionResult<S>>

Resolves the value of a single field on this GraphQLValueAsync.

pub fn resolve_into_type_async<'a>(
    &'a self,
    info: &'a Self::TypeInfo,
    type_name: &str,
    selection_set: Option<&'a [Selection<'a, S>]>,
    executor: &'a Executor<'a, 'a, Self::Context, S>
) -> BoxFuture<'a, ExecutionResult<S>>

Resolves this GraphQLValueAsync (being an interface or an union) into a concrete downstream object type.

impl<T: Hash> Hash for Nullable<T>

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

Feeds this value into the given Hasher.

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

Feeds a slice of this type into the given Hasher.

impl<S, T> IsInputType<S> for Nullable<T> where
    T: IsInputType<S>,
    S: ScalarValue, 

pub fn mark()

An arbitrary function without meaning.

impl<T: Ord> Ord for Nullable<T>

pub fn cmp(&self, other: &Nullable<T>) -> Ordering

This method returns an Ordering between self and other.

#[must_use]pub fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

#[must_use]pub fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

#[must_use]pub fn clamp(self, min: Self, max: Self) -> Self

Restrict a value to a certain interval.

impl<T: PartialEq> PartialEq<Nullable<T>> for Nullable<T>

pub fn eq(&self, other: &Nullable<T>) -> bool

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

pub fn ne(&self, other: &Nullable<T>) -> bool

This method tests for !=.

impl<T: PartialOrd> PartialOrd<Nullable<T>> for Nullable<T>

pub fn partial_cmp(&self, other: &Nullable<T>) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

pub fn lt(&self, other: &Nullable<T>) -> bool

This method tests less than (for self and other) and is used by the < operator.

pub fn le(&self, other: &Nullable<T>) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

pub fn gt(&self, other: &Nullable<T>) -> bool

This method tests greater than (for self and other) and is used by the > operator.

pub fn ge(&self, other: &Nullable<T>) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<T> StructuralEq for Nullable<T>

impl<T> StructuralPartialEq for Nullable<T>

impl<S, T> ToInputValue<S> for Nullable<T> where
    T: ToInputValue<S>,
    S: ScalarValue, 

pub fn to_input_value(&self) -> InputValue<S>

Performs the conversion.