Enum ForeignKey 

pub enum ForeignKey<T: Model> {
    PrimaryKey(T::PrimaryKey),
    Model(Box<T>),
}

Available on crate feature db only.

A foreign key to another model.

Internally, this is represented either as a primary key (in case the model has not been retrieved from the database) or as the model itself.

Examples

use cot::db::{Auto, Database, ForeignKey, Model, model};
use cot::response::Response;

#[model]
struct MyModel {
    #[model(primary_key)]
    id: Auto<i32>,
    user: ForeignKey<User>,
}

#[model]
struct User {
    #[model(primary_key)]
    id: Auto<i32>,
}

async fn index(db: Database) -> cot::Result<Response> {
    let mut user = User { id: Auto::auto() };
    user.save(&db).await?;

    let mut my_model = MyModel {
        id: Auto::auto(),
        user: ForeignKey::from(user),
    };
    my_model.save(&db).await?;

    // ...
}

Variants

PrimaryKey(T::PrimaryKey)

The primary key of the referenced model; used when the model has not been retrieved from the database yet or when it’s unnecessary to store the entire model instance.

Model(Box<T>)

The referenced model.

Implementations

impl<T: Model> ForeignKey<T>

pub fn primary_key(&self) -> &T::PrimaryKey

Returns the primary key of the referenced model.

pub fn model(&self) -> Option<&T>

Returns the model, if it has been stored in this ForeignKey instance, or None otherwise.

pub fn unwrap(self) -> T

Unwrap the foreign key, returning the model.

Panics

Panics if the model has not been stored in this ForeignKey instance.

pub async fn get<DB: DatabaseBackend>(&mut self, db: &DB) -> Result<&T>

Retrieve the model from the database, if needed, and return it.

If the model has already been retrieved, this method will return it.

This method will replace the primary key with the model instance if the primary key is stored in this ForeignKey instance.

Errors

Returns a DatabaseError::ForeignKeyNotFound error if the model could not be found in the database.

Returns an error if there was a problem communicating with the database.

Trait Implementations

impl<T> AsFormField for ForeignKey<T>

where T: Model, <T as Model>::PrimaryKey: AsFormField,

type Type = <<T as Model>::PrimaryKey as AsFormField>::Type

The form field type associated with the field.

fn new_field( options: FormFieldOptions, custom_options: <Self::Type as FormField>::CustomOptions, ) -> Self::Type

Creates a new form field with the given options and custom options.

fn clean_value(field: &Self::Type) -> Result<Self, FormFieldValidationError>

where Self: Sized,

Validates the value of the field and converts it to the final type. This method should return an error if the value is invalid.

fn to_field_value(&self) -> String

Returns self as a value that can be set with FormField::set_value.

impl<T: Clone + Model> Clone for ForeignKey<T>

where T::PrimaryKey: Clone,

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

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T: Model + Send + Sync> DatabaseField for ForeignKey<T>

const NULLABLE: bool = <T::PrimaryKey>::NULLABLE

Whether the field can be NULL in the database.

const TYPE: ColumnType = <T::PrimaryKey>::TYPE

The type of the column in the database as one of the variants of the ColumnType enum.

impl<T: Debug + Model> Debug for ForeignKey<T>

where T::PrimaryKey: Debug,

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

Formats the value using the given formatter.

impl<T: Model> From<&T> for ForeignKey<T>

fn from(model: &T) -> Self

Converts to this type from the input type.

impl<T: Model> From<T> for ForeignKey<T>

fn from(model: T) -> Self

Converts to this type from the input type.

impl<T: Model + Send + Sync> FromDbValue for ForeignKey<T>

fn from_sqlite(value: SqliteValueRef<'_>) -> Result<Self>

Available on crate feature sqlite only.

Converts the given SQLite database value to a Rust value.

fn from_postgres(value: PostgresValueRef<'_>) -> Result<Self>

Available on crate feature postgres only.

Converts the given PostgreSQL database value to a Rust value.

fn from_mysql(value: MySqlValueRef<'_>) -> Result<Self>

Available on crate feature mysql only.

Converts the given MySQL database value to a Rust value.

impl<T: Model + Send + Sync> IntoField<ForeignKey<T>> for &T

fn into_field(self) -> ForeignKey<T>

Converts the type to the field type.

impl<T: Model> PartialEq for ForeignKey<T>

where T::PrimaryKey: PartialEq,

fn eq(&self, other: &Self) -> bool

Tests for self and other values to be equal, and is used by ==.

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

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

impl<T: Model + Send + Sync> ToDbFieldValue for ForeignKey<T>

fn to_db_field_value(&self) -> DbFieldValue

Converts the Rust value to a DbFieldValue that indicates whether the value should be automatically generated by the database, or contains a specific, explicitly provided value.

impl<T: Model> Eq for ForeignKey<T>

where T::PrimaryKey: Eq,