HasOne

A one-to-one relationship represents a fundamental type of database association. As an example, consider a User model linked to a UserInfo model. To establish this connection, we define a method called userInfo within the User model. This userInfo method invokes the HasOne method and returns its output.

HasOne Class Structure

class HasOne {
    final Type model;
    final String? foreignKey;
    final String? localKey;
    final Function? onQuery;
    final bool? eager;

    const HasOne(this.model,
        {this.foreignKey, this.localKey, this.onQuery, this.eager});
}

User ModelUserInfo Model

@DoxModel()
class User extends UserGenerator {
    @Column()
    String? name;

    @HasOne(UserInfo)
    UserInfo? userInfo;
}

@DoxModel()
class UserInfo extends UserInfoGenerator {
    @Column()
    String? userId;

    @Column()
    String? address;

    @Column(name: 'house_number')
    String? houseNumber;
}

Usage

$getRelation

User? user = await User().find(1);
await user?.$getRelation('userInfo')

UserInfo userInfo = user?.userInfo;

Info

When eager is true the $getRelation do not need to call.

preload

User? user = await User().preload('userInfo').find(1);
UserInfo userInfo = user?.userInfo;

Info

When eager is true the preload do not need to call.

related

User? user = await User().find(1);
UserInfo userInfo = await user?.related<UserInfo>('userInfo')?.where('foo', 'bar').getFirst();

Options

model

@HasOne(UserInfo)
UserInfo? userInfo;

foreignKey

@HasOne(UserInfo, foreignKey: 'user_id')
UserInfo? userInfo;

localKey

@HasOne(UserInfo, foreignKey: 'user_id', localKey: 'id')
UserInfo? userInfo;

onQuery

@DoxModel()
class User extends UserGenerator {
    @HasOne(UserInfo, onQuery: onUserInfoQuery)
    UserInfo? userInfo;

    static QueryBuilder<UserInfo> onUserInfoQuery(UserInfo q) {
        return q.where('status', 'active');
    }
}

Info

onQuery method must be a static method inside the model.

eager

@HasOne(UserInfo, eager: true)
UserInfo? userInfo;