polymorphicBelongsTo

A polymorphicBelongsTo relationship is a many-to-one relationship. This relationship is used when an entity can belong to multiple types of entities. The classic example for this type of relationship is Posts, Videos, and Comments. For instance, a Comment may belong to a Post or a Video.

// Comment.cfc
component extends="quick.models.BaseEntity" {

    function post() {
        return polymorphicBelongsTo( "commentable" );
    }

}

The only value passed to polymorphicBelongsTo is a prefix for the polymorphic type. A common convention where is to add able to the end of the entity name, though this is not automatically done. In our example, this prefix is commentable. This tells quick to look for a commentable_type and a commentable_id column in our Comment entity. It stores our entity's mapping as the _type and our entity's primary key value as the _id.

When retrieving a polymorphicBelongsTo relationship the _id is used to retrieve a _type from the database.

The inverse of polymorphicBelongsTo is also polymorphicHasMany. It is important to choose the right relationship for your database structure. hasOne assumes that the related model has the foreign key for the relationship.

// Post.cfc
component extends="quick.models.BaseEntity" {

    function comments() {
       return polymorphicHasMany( "Comment", "commentable" );
    }

}

// Video.cfc
component extends="quick.models.BaseEntity" {

    function comments() {
        return polymorphicHasMany( "Comment", "commentable" );
    }

}