Select

Once you have defined the entity, you are ready to retrieve data from the database. Each row of data in the database corresponds to a Model.

By default, SeaORM will select all columns defined in the Column enum.

Find by Primary Key

Find a model by its primary key, it can be a single key or composite key. We start by calling find_by_id on Entity which helps you construct the select query and condition automatically. Then, fetch a single model from the database with the one method.

use super::cake::Entity as Cake;
use super::cake_filling::Entity as CakeFilling;

// Find by primary key
let cheese: Option<cake::Model> = Cake::find_by_id(1).one(db).await?;

// Find by composite primary keys
let vanilla: Option<cake_filling::Model> = CakeFilling::find_by_id((6, 8)).one(db).await?;

Find with Conditions and Orders

In addition to retrieving a model by primary key, you can also retrieve one or more models matching specific conditions in a certain order. The find method gives you access to the query builder in SeaORM. It supports the construction of all common select expressions like where and order by. They can be constructed using filter and order_by_* methods respectively.

Read more about conditional expression.

let chocolate: Vec<cake::Model> = Cake::find()
    .filter(cake::Column::Name.contains("chocolate"))
    .order_by_asc(cake::Column::Name)
    .all(db)
    .await?;

Find Related Models

Read more about table joins.

Lazy Loading

Use the find_related method.

Related models are loaded on demand when you ask for them, preferable if you want to load related models based on some application logic. Note that lazy loading will increase database round trips compared to eager loading.

// Find a cake model first
let cheese: Option<cake::Model> = Cake::find_by_id(1).one(db).await?;
let cheese: cake::Model = cheese.unwrap();

// Then, find all related fruits of this cake
let fruits: Vec<fruit::Model> = cheese.find_related(Fruit).all(db).await?;

Eager Loading

All related models are loaded at once. This provides minimum overhead on database round trips compared to lazy loading.

One to One

Use the find_also_related method.

let cake_and_fruit: Vec<(cake::Model, Option<fruit::Model>)> = Cake::find().find_also_related(Fruit).all(db).await?;

One to Many

Using the find_with_related method, the related models will be grouped by the parent models.

let cake_with_fruits: Vec<(cake::Model, Vec<fruit::Model>)> = Cake::find()
    .find_with_related(Fruit)
    .all(db)
    .await?;

info

Since 0.9.0, SelectTwoMany::one() method has been dropped:

let cake_with_fruits: Option<(cake::Model, Option<fruit::Model>)> = Cake::find()
    .find_with_related(Fruit)
    .one(db) // This method has been dropped
    .await?;

SelectTwoMany is for selecting models of a one-to-many relationship but SelectTwoMany::one() returns Option<(E, Option<F>)> and the return value is a pair of models instead of (E, Vec<F>) which is a weird query result for a one-to-many relationship.

Users are advised to query (E, Vec<F>) by first querying E from the database, then use find_related method to query Vec<F>. Read lazy loading for details.

If you are building a web API that perform selecting nested relation extensively. Consider serving a GraphQL server instead. seaography is a GraphQL framework for building GraphQL resolvers using SeaORM entities. With GraphQL resolver in place select above nested relation is straightforward and easy. Check "Getting Started with Seaography" to learn more.

Paginate Result

Convert any SeaORM select into a paginator with custom page size.

use sea_orm::{entity::*, query::*, tests_cfg::cake};
let mut cake_pages = cake::Entity::find()
    .order_by_asc(cake::Column::Id)
    .paginate(db, 50);
 
while let Some(cakes) = cake_pages.fetch_and_next().await? {
    // Do something on cakes: Vec<cake::Model>
}

Cursor Pagination

Use cursor pagination If you want to paginate rows based on column(s) such as the primary key.

use sea_orm::{entity::*, query::*, tests_cfg::cake};
// Create a cursor that order by `cake`.`id`
let mut cursor = cake::Entity::find().cursor_by(cake::Column::Id);

// Filter paginated result by `cake`.`id` > 1 AND `cake`.`id` < 100
cursor.after(1).before(100);

// Get first 10 rows (order by `cake`.`id` ASC)
for cake in cursor.first(10).all(db).await? {
    // Do something on cake: cake::Model
}

// Get last 10 rows (order by `cake`.`id` DESC but rows are returned in ascending order)
for cake in cursor.last(10).all(db).await? {
    // Do something on cake: cake::Model
}

Paginate rows based on a composite primary key is also available.

use sea_orm::{entity::*, query::*, tests_cfg::cake_filling};
let rows = cake_filling::Entity::find()
    .cursor_by((cake_filling::Column::CakeId, cake_filling::Column::FillingId))
    .after((0, 1))
    .before((10, 11))
    .first(3)
    .all(&db)
    .await?,

Select custom

If you want to select custom columns and expressions, read the custom select section.