pub struct OptionQuery;
Expand description

Implement QueryKindTrait with query being Option<Value>

NOTE: it doesn’t support a generic OnEmpty. This means only None can be returned when no value is found. To use another OnEmpty implementation, ValueQuery can be used instead.

Trait Implementations

Metadata for the storage kind.

Type returned on query

Convert an optional value (i.e. some if trie contains the value or none otherwise) to the query. Read more

Convert a query to an optional value.

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Convert from a value of T into an equivalent instance of Option<Self>. Read more

Consume self to return Some equivalent value of Option<T>. Read more

Convert Box<dyn Trait> (where Trait: Downcast) to Box<dyn Any>. Box<dyn Any> can then be further downcast into Box<ConcreteType> where ConcreteType implements Trait. Read more

Convert Rc<Trait> (where Trait: Downcast) to Rc<Any>. Rc<Any> can then be further downcast into Rc<ConcreteType> where ConcreteType implements Trait. Read more

Convert &Trait (where Trait: Downcast) to &Any. This is needed since Rust cannot generate &Any’s vtable from &Trait’s. Read more

Convert &mut Trait (where Trait: Downcast) to &Any. This is needed since Rust cannot generate &mut Any’s vtable from &mut Trait’s. Read more

Convert Arc<Trait> (where Trait: Downcast) to Arc<Any>. Arc<Any> can then be further downcast into Arc<ConcreteType> where ConcreteType implements Trait. Read more

Performs the conversion.

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more

Instruments this type with the current Span, returning an Instrumented wrapper. Read more

Performs the conversion.

Get a reference to the inner from the outer.

Get a mutable reference to the inner from the outer.

Should always be Self

Convert from a value of T into an equivalent instance of Self. Read more

Consume self to return an equivalent value of T. Read more

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.

The counterpart to unchecked_from.

Consume self to return an equivalent value of T.

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more