Demo GraphQL with C#

GraphQL is a query language for API, and a server-side runtime for executing queries using a type system define for data. GraphQL isn't tied to any specific database or storage engine and is instead backed by existing code and data.

GraphQL is a new API standard that provides a more efficient, powerful, and flexible alternative to REST. It was developed and open sourced by Facebook and is now maintained by a large community of companies and individuals from all over the world.

At its core, GraphQL enables declarative data fetching where a client can specify exactly what data it needs from an API.

Instead of multiple endpoints that return fixed data structures, a GraphQL server only exposes a single endpoint and responds with precisely the data that a client asked for.

Tools

• Prisma creates tools and that replaces traditional ORMs. Prisma enriches the GraphQL ecosystem and community by creating high-quality tools and software.
• Hasura is an open source engine that connects to your databases & microservices and auto-generates a production-ready GraphQL backend. Hasura gives you realtime GraphQL APIs that are high-performance, scalable, extensible & secure (with authorization baked in).

GraphQL vs REST API

Over-Fetching and Under-Fetching

api/users/{id}
api/users/{id}/posts
api/users/{id}/followers

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There are two libraries to expose GraphQL endpoint:

• 🏆graphql-dotnet/graphql-dotnet
• ⭐ChilliCream/hotchocolate
  • STEP #1: dotnet add package HotChocolate.AspNetCore
  • STEP #2: Define the types
  • STEP #3: Add a Query type
  • STEP #4: Add GraphQL services

    builder.Services
       .AddGraphQLServer()
       .AddQueryType<Query>();

  • STEP #5: Map the GraphQL endpoint

    var app = builder.Build();
    // map GraphQL
    app.MapGraphQL();
    app.Run();

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Operations: GraphQL vs REST

Operation	GraphQL	REST
Read	Query	GET
Write	Mutation	PUT, POST, PATCH, DELETE
Event	Subscription	N/A

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Links:

• The Fullstack Tutorial for GraphQL
• Code using GraphQL
• Next-generation Node.js and TypeScript ORM
• Hasura
• github.com/graphql/graphql-playground
• GraphQL for .NET
• ChilliCream/hotchocolate-examples
• ChilliCream/graphql-workshop