Join Annotation

The @Join annotation is used to define associations between entities, supporting one-to-one, one-to-many, many-to-one, and many-to-many relationships.

To execute queries that include annotation-generated joins, use BaseMapper methods with the WithJoin suffix.

Parameters

Parameter	Type	Default	Description
selfField	String	""	The field name in the source entity used for the join
targetField	String	""	The field name in the target entity used for the join
joinTable	String	""	The join (pivot) table name (required for many-to-many)
joinSelfColumn	String	""	The column in the join table that references the source entity
joinTargetColumn	String	""	The column in the join table that references the target entity

One-to-One

Used when two entities have a one-to-one relationship.

import com.tang.kite.annotation.Join;
import com.tang.kite.annotation.id.Id;
import com.tang.kite.annotation.id.IdType;

public class Account {

    @Id(type = IdType.AUTO)
    private Long id;

    private String username;

    @Join(selfField = "id", targetField = "accountId")
    private Role role;

}

import com.tang.kite.annotation.id.Id;
import com.tang.kite.annotation.id.IdType;

public class Role {

    @Id(type = IdType.AUTO)
    private Long id;

    private Long accountId;

    private String name;

}

One-to-Many

Used when one entity is associated with multiple entities.

import com.tang.kite.annotation.Join;
import com.tang.kite.annotation.id.Id;
import com.tang.kite.annotation.id.IdType;

public class Account {

    @Id(type = IdType.AUTO)
    private Long id;

    private String username;

    @Join(selfField = "id", targetField = "accountId")
    private List<Role> roles;

}

import com.tang.kite.annotation.id.Id;
import com.tang.kite.annotation.id.IdType;

public class Role {

    @Id(type = IdType.AUTO)
    private Long id;

    private Long accountId;

    private String name;

}

Many-to-One

Used when multiple entities reference the same target entity.

import com.tang.kite.annotation.Join;
import com.tang.kite.annotation.id.Id;
import com.tang.kite.annotation.id.IdType;

public class Account {

    @Id(type = IdType.AUTO)
    private Long id;

    private String username;

    @Join(
        selfField = "id",
        targetField = "id",
        joinTable = "account_role",
        joinSelfColumn = "account_id",
        joinTargetColumn = "role_id"
    )
    private Role role;

}

public class AccountRole {

    private Long accountId;

    private Long roleId;

}

import com.tang.kite.annotation.id.Id;
import com.tang.kite.annotation.id.IdType;

public class Role {

    @Id(type = IdType.AUTO)
    private Long id;

    private Long accountId;

    private String name;

}

Many-to-Many

Used when two entities have a many-to-many relationship and a join table is required.

import com.tang.kite.annotation.Join;
import com.tang.kite.annotation.id.Id;
import com.tang.kite.annotation.id.IdType;

public class Account {

    @Id(type = IdType.AUTO)
    private Long id;

    private String username;

    @Join(
        selfField = "id",
        targetField = "id",
        joinTable = "account_role",
        joinSelfColumn = "account_id",
        joinTargetColumn = "role_id"
    )
    private List<Role> roles;

}

public class AccountRole {

    private Long accountId;

    private Long roleId;

}

import com.tang.kite.annotation.id.Id;
import com.tang.kite.annotation.id.IdType;

public class Role {

    @Id(type = IdType.AUTO)
    private Long id;

    private Long accountId;

    private String name;

}