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Hot Chocolate Data

In this chapter, we will begin building our webshop API. We will start with a basic GraphQL server that exposes a Brand, a Product, and a ProductType entity to enable the webshop to fetch available products. This API represents the product catalog.

In this chapter, we will cover the following topics:

  • Basic Dependency Injection (DI) integration with resolvers.
  • Exposing lists of entities from a database.
  • Cursor-based pagination.
  • Filtering, sorting, and projecting data.

Preparations​

Open the lesson directory in your IDE.

code src/Chapter2/Lesson1/Begin

In our example, we already have a basic GraphQL server set up with Hot Chocolate that exposes the Brand entity through the GraphQL Query type. We also have all the entities and the database context already set up.

note

The Query class will represent the GraphQL root type for query operations. Query operations in GraphQL represent side-effect-free read operations.

Before we can test this server, we need to set up our database server. For this workshop, we will use PostgreSQL. We have prepared a docker-compose file for you, located in the src/Chapter2/Lesson1/Begin directory.

docker-compose up -d

This will start a PostgreSQL database server on your local machine. The server will be available at localhost:5432. We have also set up pgAdmin for you, so you can inspect the database. The pgAdmin server will be available at localhost:5050. The username and password can be found in the docker-compose file.

Tasks​

  1. Start the GraphQL server and explore the schema in Banana Cake Pop.
  2. Try to query the brands field on the Query type.
  3. Examine the filters on the brands field and consider the limitations and issues they might introduce.
  4. Implement a new resolver for the products field on the Query type that fetches all products from the database, allowing for filtering and sorting of the dataset.
  5. Implement a new resolver for the productTypes field on the Query type that fetches all product types from the database, allowing for filtering and sorting of the dataset.