MorphOne Relationship

The MorphOne relationship represents a one-to-one polymorphic relationship where a parent model (e.g., Post, Video) can have a single related child record (e.g., Image), and those children can belong to different parent types. The polymorphic keys are stored on the child table.

Explanation

For example, both a Post and a Video can have one Image. Each Image stores imageable_type (e.g., 'post' or 'video') and imageable_id (the parent id):

In this setup, a Post or Video can have one Image, and the same Image table can be used for both.

Defining the Relationship

Define MorphOne on the parent, pointing to the child table and specifying the foreign key and type columns:

relationships: {
  image: [MorphOne, 'image', 'imageable_id', 'imageable_type']
}

• The first argument is the child table name ('image').
• The second is the foreign key on the child ('imageable_id').
• The third is the type key on the child ('imageable_type').

Example

{
  models: {
    post: {
      schema: '++id,title',
      properties: ['id', 'title'],
      primaryKey: 'id',
      relationships: {
        image: [MorphOne, 'image', 'imageable_id', 'imageable_type'],
      },
    },
    video: {
      schema: '++id,url',
      properties: ['id', 'url'],
      primaryKey: 'id',
      relationships: {
        image: [MorphOne, 'image', 'imageable_id', 'imageable_type'],
      },
    },
    image: {
      schema: '++id,url,imageable_id,imageable_type',
      properties: ['id', 'url', 'imageable_id', 'imageable_type'],
      primaryKey: 'id',
      relationships: {},
    },
  }
}

Note

MorphOne is used when a parent can have only one polymorphic child, and the child table stores the type and id of the parent. If you need multiple children, use MorphMany instead.