Understanding GraphQL for Beginners–Part Two

Summary

The second part of this beginner tutorial uses a food-focused Ruby on Rails application to show how GraphQL fields expose database data. It reviews the graphql directory, where mutations hold data-changing classes, types define returned structures, and food_app_schema.rb defines available queries. It distinguishes root fields, which are GraphQL entry points that define response structure, from object fields, which represent attributes, then demonstrates generating Food and Nutrition types and adding an all_food root field with a non-null list return type. Through GraphiQL at localhost:3000/graphiql, it runs selective queries, adds nutrition to food, and introduces an id argument for retrieving one record; requests pass through graphql_controller’s execute method and return JSON responses.

Takeaways

1. 1

   Root fields are entry points to a GraphQL server and define response structure, while object fields represent an object's attributes.

2. 2

   The Food type can expose its associated Nutrition record by adding field :nutrition, Types::NutritionType, null: true.

3. 3

   GraphiQL documents schema queries and executes requests; graphql_controller’s execute method processes them and returns a JSON response.