Struct frame_support::storage::types::OptionQuery

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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§

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impl<Value> QueryKindTrait<Value, GetDefault> for OptionQuerywhere Value: FullCodec + 'static,

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const METADATA: StorageEntryModifierIR = StorageEntryModifierIR::Optional

Metadata for the storage kind.
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type Query = Option<Value>

Type returned on query
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fn from_optional_value_to_query(v: Option<Value>) -> Self::Query

Convert an optional value (i.e. some if trie contains the value or none otherwise) to the query.
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fn from_query_to_optional_value(v: Self::Query) -> Option<Value>

Convert a query to an optional value.

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fn type_id(&self) -> TypeId

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impl<T> CheckedConversion for T

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fn checked_from<T>(t: T) -> Option<Self>where Self: TryFrom<T>,

Convert from a value of T into an equivalent instance of Option<Self>. Read more
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fn checked_into<T>(self) -> Option<T>where Self: TryInto<T>,

Consume self to return Some equivalent value of Option<T>. Read more
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const ALIGN: usize = mem::align_of::<T>()

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type Init = T

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

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fn unchecked_into(self) -> T

The counterpart to unchecked_from.
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