Trait Model

pub trait Model:
    Sized
    + Send
    + 'static {
    type Fields;
    type PrimaryKey: PrimaryKey;

    const APP_NAME: &'static str;
    const TABLE_NAME: Identifier;
    const PRIMARY_KEY_NAME: Identifier;
    const COLUMNS: &'static [Column];

    // Required methods
    fn from_db(db_row: Row) -> Result<Self>;
    fn update_from_db(&mut self, db_row: Row, columns: &[usize]) -> Result<()>;
    fn primary_key(&self) -> &Self::PrimaryKey;
    fn set_primary_key(&mut self, primary_key: Self::PrimaryKey);
    fn get_values(&self, columns: &[usize]) -> Vec<&dyn ToDbFieldValue>;
    fn get_by_primary_key<'life0, 'async_trait, DB>(
        db: &'life0 DB,
        pk: Self::PrimaryKey,
    ) -> Pin<Box<dyn Future<Output = Result<Option<Self>>> + Send + 'async_trait>>
       where DB: 'async_trait + DatabaseBackend,
             Self: 'async_trait,
             'life0: 'async_trait;

    // Provided methods
    fn objects() -> Query<Self> { ... }
    fn save<'life0, 'life1, 'async_trait, DB>(
        &'life0 mut self,
        db: &'life1 DB,
    ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + 'async_trait>>
       where DB: 'async_trait + DatabaseBackend,
             Self: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait { ... }
    fn insert<'life0, 'life1, 'async_trait, DB>(
        &'life0 mut self,
        db: &'life1 DB,
    ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + 'async_trait>>
       where DB: 'async_trait + DatabaseBackend,
             Self: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait { ... }
    fn update<'life0, 'life1, 'async_trait, DB>(
        &'life0 mut self,
        db: &'life1 DB,
    ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + 'async_trait>>
       where DB: 'async_trait + DatabaseBackend,
             Self: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait { ... }
}

Available on crate feature db only.

A model trait for database models.

This trait is used to define a model that can be stored in a database. It is used to define the structure of the model, the table name, and the columns.

Deriving

This trait can, and should be derived using the model attribute macro. This macro generates the implementation of the trait for the type, including the implementation of the Fields helper struct.

use cot::db::model;

#[model]
struct MyModel {
    #[model(primary_key)]
    id: i32,
    name: String,
}

Required Associated Constants

const APP_NAME: &'static str

The name of the app this model is defined in.

const TABLE_NAME: Identifier

The name of the table in the database.

const PRIMARY_KEY_NAME: Identifier

The name of the primary key column in the database.

const COLUMNS: &'static [Column]

The columns of the model.

Required Associated Types

type Fields

A helper structure for the fields of the model.

This structure should a constant FieldRef instance for each field in the model. Note that the names of the fields should be written in UPPER_SNAKE_CASE, just like other constants in Rust.

type PrimaryKey: PrimaryKey

The primary key type of the model.

Required Methods

fn from_db(db_row: Row) -> Result<Self>

Creates a model instance from a database row.

Errors

This method can return an error if the data in the row is not compatible with the model.

fn update_from_db(&mut self, db_row: Row, columns: &[usize]) -> Result<()>

Updates the model instance from a database row.

This is used by the ORM to update the model instance after saving with the data for the Auto fields.

Errors

This method can return an error if the data in the row is not compatible with the model.

fn primary_key(&self) -> &Self::PrimaryKey

Returns the primary key of the model.

fn set_primary_key(&mut self, primary_key: Self::PrimaryKey)

Used by the ORM to set the primary key of the model after it has been saved to the database.

fn get_values(&self, columns: &[usize]) -> Vec<&dyn ToDbFieldValue>

Gets the values of the model for the given columns.

fn get_by_primary_key<'life0, 'async_trait, DB>( db: &'life0 DB, pk: Self::PrimaryKey, ) -> Pin<Box<dyn Future<Output = Result<Option<Self>>> + Send + 'async_trait>>

where DB: 'async_trait + DatabaseBackend, Self: 'async_trait, 'life0: 'async_trait,

Queries the database for a model instance with the given primary key.

Errors

This method can return an error if the model instance could not be found in the database, or there was a problem with the database connection.

Provided Methods

fn objects() -> Query<Self>

Returns a query for all objects of this model.

fn save<'life0, 'life1, 'async_trait, DB>( &'life0 mut self, db: &'life1 DB, ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + 'async_trait>>

where DB: 'async_trait + DatabaseBackend, Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Inserts the model instance to the database, or updates an instance with the same primary key if it already exists.

To force insert or force update, use the Self::insert or Self::update methods instead.

Errors

This method can return an error if the model instance could not be inserted into the database, for instance because the migrations haven’t been applied, or there was a problem with the database connection.

fn insert<'life0, 'life1, 'async_trait, DB>( &'life0 mut self, db: &'life1 DB, ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + 'async_trait>>

where DB: 'async_trait + DatabaseBackend, Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Insert the model instance to the database.

Errors

This method can return an error if the model instance could not be inserted into the database, for instance because the migrations haven’t been applied, or there was a problem with the database connection.

fn update<'life0, 'life1, 'async_trait, DB>( &'life0 mut self, db: &'life1 DB, ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + 'async_trait>>

where DB: 'async_trait + DatabaseBackend, Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Update the model instance in the database.

Errors

This method can return an error if the model instance could not be inserted into the database, for instance because the migrations haven’t been applied, or there was a problem with the database connection.

This method can return an error if the model with the given primary key could not be found in the database.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl Model for DatabaseUser

const COLUMNS: &'static [Column]

const APP_NAME: &'static str = "cot"

const TABLE_NAME: Identifier

const PRIMARY_KEY_NAME: Identifier

type Fields = DatabaseUserFields

type PrimaryKey = Auto<i64>