Struct butane::Many

pub struct Many<T>where
    T: DataObject,{ /* private fields */ }

Used to implement a many-to-many relationship between models.

Creates a new table with columns “owner” and “has” If type T has a many-to-many relationship with U, owner type is T::PKType, has is U::PKType. Table name is T_foo_Many where foo is the name of the Many field

Implementations

impl<T> Many<T>where T: DataObject,

pub fn new() -> Many<T>

Constructs a new Many. init must be called before it can be loaded or saved (or those methods will return Error::NotInitialized). init will automatically be called when a DataObject with a Many field is loaded or saved.

pub fn ensure_init( &mut self, item_table: &'static str, owner: SqlVal, owner_type: SqlType )

Used by macro-generated code. You do not need to call this directly.

pub fn add(&mut self, new_val: &T) -> Result<(), Error>

Adds a value. Returns Err(ValueNotSaved) if the provided value uses automatic primary keys and appears to have an uninitialized one.

pub fn remove(&mut self, val: &T)

Removes a value.

pub fn get(&self) -> Result<impl Iterator<Item = &T>, Error>

Returns a reference to the value. It must have already been loaded. If not, returns Error::ValueNotLoaded

pub fn save(&mut self, conn: &impl ConnectionMethods) -> Result<(), Error>

Used by macro-generated code. You do not need to call this directly.

pub fn load( &self, conn: &impl ConnectionMethods ) -> Result<impl Iterator<Item = &T>, Error>

Loads the values referred to by this foreign key from the database if necessary and returns a reference to them.

pub fn columns(&self) -> [Column; 2]

Trait Implementations

impl<T> Clone for Many<T>where T: Clone + DataObject,

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

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T> Debug for Many<T>where T: Debug + DataObject,

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

Formats the value using the given formatter.

impl<T> Default for Many<T>where T: DataObject,

fn default() -> Many<T>

Returns the “default value” for a type.

impl<'de, T> Deserialize<'de> for Many<T>where T: DataObject,

fn deserialize<__D>( __deserializer: __D ) -> Result<Many<T>, <__D as Deserializer<'de>>::Error>where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<T> Dummy<Faker> for Many<T>where T: DataObject,

Fake data support is currently limited to empty Many relationships.

fn dummy_with_rng<R>(_: &Faker, _rng: &mut R) -> Many<T>where R: Rng + ?Sized,

Generate a dummy value for a given type using a random number generator.

fn dummy(config: &T) -> Self

Generate a dummy value for a type.

impl<T> PartialEq<Many<T>> for Many<T>where T: DataObject,

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

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

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T> Serialize for Many<T>where T: DataObject,

fn serialize<__S>( &self, __serializer: __S ) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>where __S: Serializer,

Serialize this value into the given Serde serializer.

impl<T> Eq for Many<T>where T: DataObject,