# hasManyDeep ## Usage A `hasManyDeep` relationship is either a `one-to-many` or a `many-to-many` relationship. It is used when you want to access related entities through one or more intermediate entities. For example, you may want to retrieve all the blog posts for a `Team`: ```cfscript // Team.cfc component extends="quick.models.BaseEntity" accessors="true" { function posts() { return hasManyDeep( relationName = "Post", through = [ "User" ], foreignKeys = [ "teamId", // the key on User that refers to Team "authorId" // the key on Post that refers to User ], localKeys = [ "id", // the key on Team that identifies Team "id" // the key on User that identifies User ] ); } } ``` This would generate the following SQL: ```sql SELECT * FROM `posts` INNER JOIN `users` ON `posts`.`authorId` = `users`.`id` WHERE `users`.`teamId` = ? // team.getId() ``` You can generate this same relationship using a Builder syntax: ```cfscript // Team.cfc component extends="quick.models.BaseEntity" accessors="true" { function posts() { return newHasManyDeepBuilder() .throughEntity( "User", "teamId", "id" ) .toRelated( "Post", "authorId", "id" ); } } ``` `HasManyDeep` relationships can also traverse pivot tables. For instance, a `User` may have multiple `Permissions` via a `Role` entity. ```javascript // User.cfc component extends="quick.models.BaseEntity" accessors="true" { function permissions() { return hasManyDeep( relationName = "Role", through = [ "roles_users", "Role", "permissions_roles" ], foreignKeys = [ "userId", "id", "roleId", "id" ], localKeys = [ "id", "roleId", "id", "permissionId" ] ); } } ``` {% hint style="info" %} If a mapping in the `through` array is found as a WireBox mapping, it will be treated as a Pivot Table. {% endhint %} {% hint style="info" %} If you are traversing a `polymorhpic` relationship, pass an array as the key type where the first key points to the polymorphic type column and the second key points to the identifying value. {% endhint %} ## Constraining Relationships There are two options for constraining a `HasManyDeep` relationship. The first option is by using table aliases. {% tabs %} {% tab title="Traditional Syntax" %} ```cfscript // Team.cfc component extends="quick.models.BaseEntity" accessors="true" { function activePosts() { return hasManyDeep( relationName = "Post", through = [ "User AS u" ], foreignKeys = [ "teamId", // the key on User that refers to Team "authorId" // the key on Post that refers to User ], localKeys = [ "id", // the key on Team that identifies Team "id" // the key on User that identifies User ] ).where( "u.active", 1 ); } } ``` {% endtab %} {% tab title="Builder Syntax" %} ```cfscript // Team.cfc component extends="quick.models.BaseEntity" accessors="true" { function activePosts() { return newHasManyDeepBuilder() .throughEntity( "User AS u", "teamId", "id" ) .toRelated( "Post", "authorId", "id" ) .where( "u.active", 1 ); } } ``` {% endtab %} {% endtabs %} This produces the following SQL: ```sql SELECT * FROM `posts` INNER JOIN `users` AS `u` ON `posts`.`authorId` = `users`.`id` WHERE `u`.`teamId` = ? // team.getId() AND `u`.`active` = ? // 1 ``` If you want to use scopes or avoid table aliases, you can use callback functions to constrain the relationship: {% tabs %} {% tab title="Traditional Syntax" %} ```cfscript // Team.cfc component extends="quick.models.BaseEntity" accessors="true" { function activePosts() { return hasManyDeep( relationName = "Post", through = [ () => newEntity( "User ).active() ], foreignKeys = [ "teamId", // the key on User that refers to Team "authorId" // the key on Post that refers to User ], localKeys = [ "id", // the key on Team that identifies Team "id" // the key on User that identifies User ] ); } } ``` {% endtab %} {% tab title="Builder Syntax" %} ```cfscript // Team.cfc component extends="quick.models.BaseEntity" accessors="true" { function activePosts() { return newHasManyDeepBuilder() .throughEntity( entityName = "User", foreignKey = "teamId", localKey = "id", callback = ( user ) => user.active() ) .toRelated( "Post", "authorId", "id" ) } } ``` {% endtab %} {% endtabs %} ## Signature
NameTypeRequiredDefaultDescription
relationNameString | Function | QuickBuilder | IRelationshiptrueA mapping name to the final related entity, a function that produces a QuickBuilder or Relationship instance, or a QuickBuilder or Relationship instance.
throughArray<String | Function | QuickBuilder | IRelationship>true

The entities to traverse through from the parent (current) entity to get to the relatedEntity.

Each item in the array can be either a mapping name to the final related entity, a function that produces a QuickBuilder or Relationship instance, or a QuickBuilder or Relationship instance.

foreignKeysArray<String>trueAn array of foreign keys traversing to the relatedEntity.

The length of this array should be one more than the length of through.

The first key of this array would be the column on the first through entity that refers back to the parent (current) entity, and so forth.
localKeysArray<String>trueAn array of local keys traversing to the relatedEntity.

The length of this array should be one more than the length of through.

The first key of this array would be the column on the parent (current) entity that identifies it, and so forth.
nestedbooleanfalsefalseSignals the relationship that it is currently being resolved as part of another hasManyDeep relationship. This is handled by the framework when using a hasManyThrough relationship.
relationMethodNameStringfalseCurrent Method NameThe method name called to retrieve this relationship. Uses a stack backtrace to determine by default.