Relationships

belongs_to

Passing a resource that is a single entity in relationships tree will make JsonApi::Parameters assume that it is a belongs_to relationship.

Without included entity

Example:

class Movie < ActiveRecord::Model
    belongs_to :director
end

Request body:

{
    data: {
        type: 'movies',
        attributes: {
          title: 'The Terminator',
        },
        relationships: {
          director: {
            data: {
              id: 682, type: 'directors'
            }
          }
        }
    }
}

Will translate to:

{
  movie: {
    title: 'The Terminator',
    director_id: 682
  }
}

With included entity:

Example:

class Movie < ActiveRecord::Model
    belongs_to :director
    
    accepts_nested_attributes_for :director
end

Request body:

{
    data: {
        type: 'movies',
        attributes: {
          title: 'The Terminator',
        },
        relationships: {
          director: {
            data: {
              id: 682, type: 'directors'
            }
          }
        }
    },
    included: [
        {
            type: 'directors',
            id: 682,
            attributes: { 
                name: 'Some guy'
            }
        }
    ]
}

Will translate to:

{
  movie: {
    title: 'The Terminator',
    director_attributes: { id: 682, name: 'Some guy' }
  }
}

has_many

Passing a resource that is a an array of entities in relationships tree will make JsonApi::Parameters assume that it is a has_many relationship.

Without included entity

Example:

class Movie < ActiveRecord::Model
    has_many :genres
end

Request body:

{
    data: {
        type: 'movies',
        attributes: {
          title: 'The Terminator',
        },
        relationships: {
          genres: {
            data: [{
              id: 1, type: 'genres'
            },
            {
              id: 2, type: 'genres'
            }]
          }
        }
    }
}

Will translate to:

{
  movie: {
    title: 'The Terminator',
    genre_ids: [1, 2]
  }
}

With included entity:

Example:

class Movie < ActiveRecord::Model
    has_many :genres
    
    accepts_nested_attributes_for :genres
end

Request body:

{
  data: {
    type: 'movies',
    attributes: {
      title: 'The Terminator',
    },
    relationships: {
      genres: {
        data: [{
                 id: 1, type: 'genres'
               }]
      }
    }
  },
  included: [
    {
      type: 'genres',
      id: 1,
      attributes: {
        name: 'Genre one'
      }
    }
  ]
}

Will translate to:

{
  movie: {
    title: 'The Terminator',
    genres_attributes: [{ id: 1, name: 'Genre one' }]
  }
}