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Serializing JSON Data in Rails

JSON data is a big part of creating an API and curating the data in a consistent way is essential to consuming that data. When creating a Ruby on Rails API we have a few different ways to deal with this but today I’m going to talk about Active Model Serializer. It provides easy convention for managing the structure of your JSON data.

to_json

Let’s create a scenario where we had a Rails blog application. If we wanted to view an instance of Post we would also want to see the associated Author of that post. We can use the Active Record method to_json which allows us to include the necessary attributes of the Post and it’s Author . It would look like this:

# posts_controller.rb
def show
  @post = Post.find(params[:id])
  
  render json: @post.to_json(only: [:title, :description, :id],
                            include: [author: { only: [:name]}])
end

You can see in this example that we are having the controller render the JSON data which includes an Active Record relationship between a Post and Author .

However, we can see from this example that curating JSON data in this manner will get ugly very quickly. If there were any further relationships we wanted to display or if the object we wanted to render included anymore attributes it…