Struct butane::Many

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

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_ManyToMany_foo 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)

Adds a value.

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

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

Formats the value using the given formatter.

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

pub fn default() -> Many<T>

Returns the “default value” for a type.

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

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

pub 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 !=.

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

pub 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,