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HotChocolate

As explained in Building Web APIs with ASP.NET Core

HotChocolate is an open-source .NET library for building GraphQL servers and integrating GraphQL with application services and data sources.

HotChocolate is an open-source .NET library for adding a GraphQL server to an ASP.NET Core application. It supplies GraphQL services and middleware, integrates with EF Core and authorization, and includes the browser-based BananaCakePop client for testing the endpoint. For a board-game API with an existing EF Core data model, these features avoid implementing the GraphQL runtime from scratch. section 10.2.3

To add it to an existing application:

  • Install HotChocolate.AspNetCore, HotChocolate.AspNetCore.Authorization, and HotChocolate.Data.EntityFramework. The illustrated setup pins all three packages to version 12.15.2. section 10.2.3
  • Define a Query class whose methods return IQueryable results from the EF Core database context. The board-game, domain, and mechanic queries use paging, projection, filtering, and sorting attributes. section 10.2.3
  • Define mutations for changes to those entities. The illustrated update methods use DTO inputs and save through the database context; authorization attributes restrict them by role. section 10.2.3
  • Register the query and mutation types with AddGraphQLServer(), enable the corresponding features, and map the endpoint with app.MapGraphQL(). section 10.2.3
Listing 10.6 Program.cs file: GraphQL services
using MyBGList.GraphQL;                #1
 
// [...]
 
builder.Services.AddGraphQLServer()    #2
    .AddAuthorization()                #3
    .AddQueryType<Query>()             #4
    .AddMutationType<Mutation>()       #5
    .AddProjections()                  #6
    .AddFiltering()                    #7
    .AddSorting();                     #8

The service-registration chain connects the query and mutation classes to authorization, projections, filtering, and sorting. section 10.2.3

Check the endpoint

Run the application and open BananaCakePop at the illustrated local /graphql endpoint. Request the first three board games, sorted by ID, with only id, name, and year; the response contains those fields. A second query requests their domains and mechanics in the same round trip. To check writes, run an authorized updateBoardGame mutation, then query that game again to confirm its new name. section 10.2.4

How Building Web APIs with ASP.NET Core covers it

How deep it goes
Walks through package installation, query and mutation classes, service registration, endpoint mapping, and tests rather than GraphQL runtime internals.
Examples
Tests board-game field selection, related domains and mechanics, and an authorized board-game update through BananaCakePop.
What it assumes
Assumes an ASP.NET Core application with an existing EF Core data model and database context.
What you can do after
Apply it via HotChocolate to expose and test EF Core-backed GraphQL queries and authorized mutations.
How it connects
Connects GraphQL queries and mutations with EF Core, ASP.NET Core authorization, paging, filtering, sorting, and BananaCakePop.
Cover of Building Web APIs with ASP.NET Core
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Related concepts

This explainer was generated by Manning's knowledge graph from the text of Building Web APIs with ASP.NET Core. The section links point to the parts of the book it draws on.