Struct HasOne 

pub struct HasOne<T> { /* private fields */ }

A lazily-loaded has-one association.

HasOne<T> wraps an optional T that is populated when the association is eagerly loaded (via include) or accessed through a generated relation accessor. Before loading, calling get panics.

This type appears as a field on model structs for has-one relations.

Implementations

impl<T: Relation> HasOne<T>

pub fn get(&self) -> &T

Returns a reference to the loaded associated record.

Panics

Panics if the association has not been loaded.

pub fn is_unloaded(&self) -> bool

Returns true if the association has not been loaded yet.

pub fn unload(&mut self)

Clear the loaded value, returning this association to the unloaded state.

Trait Implementations

impl<T: Clone> Clone for HasOne<T>

fn clone(&self) -> HasOne<T>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T: Debug> Debug for HasOne<T>

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

Formats the value using the given formatter.

impl<T> Default for HasOne<T>

fn default() -> Self

Returns the “default value” for a type.

impl<T: Relation> Load for HasOne<T>

type Output = HasOne<T>

The concrete type produced by load.

fn ty() -> Type

Returns the stmt::Type that describes values of this type.

fn load(input: Value) -> Result<Self>

Deserialize a database Value into Self::Output.

fn ty_relation() -> Type

Returns the stmt::Type used when this type appears as a relation target. The default delegates to ty().

fn load_relation(value: Value) -> Result<Self::Output, Error>

Deserialize a value that was loaded as a relation target.

fn reload(target: &mut Self::Output, value: Value) -> Result<(), Error>

Reload the value in-place from a value returned by the database.

impl<T: Relation> Relation for HasOne<T>

type Model = <T as Relation>::Model

The target model

type Expr = <T as Relation>::Expr

The target expression (e.g. Option<Model>)

type Query = <T as Relation>::Query

The query builder type for querying this relation’s target.

type Create = <T as Relation>::Create

Create builder type for this relation’s target model

type Many = <T as Relation>::Many

HasMany relation type

type ManyField<__Origin> = <T as Relation>::ManyField<__Origin>

The field accessor type used when this model appears as the “many” side of a has-many relation, parameterized by the origin model.

type One = <T as Relation>::One

The has-one relation wrapper type for this model.

type OneField<__Origin> = <T as Relation>::OneField<__Origin>

The field accessor type used when this model appears as the “one” side of a has-one relation, parameterized by the origin model.

type OptionOne = <T as Relation>::OptionOne

The optional has-one relation wrapper type. Used when the foreign key is nullable, making the association optional.

fn new_many_field<__Origin>( path: Path<__Origin, List<Self::Model>>, ) -> Self::ManyField<__Origin>

Construct a ManyField from a path targeting a list of the model.

fn field_name_to_id(name: &str) -> FieldId

Map a field name string to its FieldId.

fn nullable() -> bool

Returns true if this relation target is nullable (i.e., wrapped in Option). The default is false.

fn new_create() -> Self::Create

Return a fresh, default-initialized create builder.