Struct butane_core::many::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() -> Self

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 get(&self) -> Result<impl Iterator<Item = &T>>

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<()>

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>>

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

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

Trait Implementations

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

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

Formats the value using the given formatter.

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

pub fn default() -> Self

Returns the "default value" for a type.

impl<T: DataObject> Eq for Many<T>

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

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

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

#[must_use]pub fn ne(&self, other: &Rhs) -> bool

This method tests for !=.