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Creating Long-Lived Web Apps with Ruby on Rails

Write APIs the Same Way We Write Other Code

Explore how to write API controllers in Rails using the same principles as other controllers. Understand the importance of namespacing routes and controllers for better separation and maintainability. Learn to centralize configurations in a base API controller while keeping business logic clean and testable.

We'll cover the following...

Ideally, a controller that powers an API should look just as plain as any other controller:

Ruby
class WidgetsController < ApplicationController
  def index
    widgets = Widget.all
    render json: { widgets: widgets }
  end
  def create
    widget = Widget.create(widget_params)
    if widget.valid?
      render json: { widget: widget }, status: 201
    else
      render json: { errors: widget.errors }, status: 422
    end
  end
end

We may not want exactly this sort of error handling, but we get the idea. There’s rarely a reason to do anything different in our API controller methods than in our non-API methods.

We would be well-served to do a couple of things before writing any API code, and that’s to create a separate routing namespace and, thus, controller namespace for our API calls. This means that while a browser might navigate to /widgets/1234 to get the view for widget 1234, an API client would access /api/widgets/1234.json to access the JSON endpoint. ...