Automatically generate API for existing database

using rails 4, you can use the scaffold, taking care to keep the data models exactly the same as the old database (i.e. the same table and column names), and then remove the migrations created with the scaffold.

let's say you have a table called Messages with columns: subject and body.

You can run:

rails g scaffold post subject:string body:text

      

        
        
        
      

    

Then remove the migration from db / migrate.

Now assuming that you have configured your rails app to properly access the database via config / database.yml you should have the json API all set up and ready to use as rails scaffold generates index.json.jbuilder and show.json.jbuilder for every resource that you scaffold.

You may need to edit the application controller to allow external API requests, but this only matters if you plan on POSTing to your API:

if you need POST, then change this line at the top of your app / controllers / application_controller.rb:

# Prevent CSRF attacks by raising an exception.
# For APIs, you may want to use :null_session instead.
protect_from_forgery with: :exception

      

        
        
        
      

    

:

protect_from_forgery with: :null_session

      

        
        
        
      

    

GET requests should work without changing the application controller.

Forgot to mention to access these resources you will be using? format = json as a parameter, so:

http://localhost:3000/posts?format=json

      

        
        
        
      

    

or

http://localhost:3000/posts/1?format=json

      

        
        
        
      

    

Will return json response for all messages or one message.