Getting started with
GraphQL on ASP.NET Core

Michael Staib

09:00 Hello, Intro, Tech Check
09:25 What is GraphQL?
09:50 BREAK (10 minutes)
10:00 GraphQL Queries
10:50 BREAK (20 minutes)
11:10 Building a GraphQL Server
12:00 BREAK (10 minutes)
12:10 DataLoader

13:00 LUNCH

14:00 Schema Design
14:50 BREAK (10 minutes)
15:00 Middleware, Pagination and Filtering
15:50 BREAK (20 minutes)
16:10 GraphQL Subscriptions
16:30 Putting GraphQL to Production
17:00 FINISH

Let us get our machines ready.

https://bit.ly/30Vtjdq

https://github.com/csharpfritz/aspnetcore-app-workshop

{
  me {
    name
  }
}
{
  "me": {
    "name": "Michael Staib"
  }
}

{
  me {
    name
  }
}
{
  me {
    name
    image {
      width
      height
      url
    }
  }
}
{
  "me": {
    "name": "Michael Staib",
    "image": {
      "width": 200,
      "height": 300,
      "url": "http://some/images/123.png"          
    }
  }
}
{
  me {
    name
    image {
      width
      height
      url
    }
  }
}
{
  me {
    name
    lastSeen
    friends {
      name
      lastSeen
    }
  }
}
{
  "me": {
    "name": "Michael Staib",
    "lastSeen": "2018-05-19T18:45",
    "friends": [
      {
        "name": "Rafael Staib",
        "lastSeen": "2018-05-24T12:37"
      },
      {
        "name": "Pascal Senn",
        "lastSeen": "2018-06-07T17:13"
      }
    ]
  }
}
{
  me {
    name
    lastSeen
    friends {
      name
      lastSeen
    }
  }
}
{
  "me": {
    "name": "Michael Staib",
    "lastSeen": "2018-05-19T18:45",
    "friends": [
      {
        "name": "Rafael Staib",
        "lastSeen": "2018-05-24T12:37"
      },
      {
        "name": "Pascal Senn",
        "lastSeen": "2018-06-07T17:13"
      }
    ]
  }
}
{
  me {
    ... PersonInfo
    friends {
      ... PersonInfo
    }
  }
}
fragment PersonInfo on Person {
  name
  lastSeen
}
  • One Endpoint
  • One Request
  • No over- or under-fetching
  • Type System
  • Predictable

https://hc-starwars.azurewebsites.net 

DataLoader

Understanding Field Middleware

[UseApplicationDbContext]
[UsePaging]
public IQueryable<Attendee> GetAttendees(
    [ScopedService] ApplicationDbContext context) => 
    context.Attendees;
protected override void Configure(
    IObjectTypeDescriptor<Query> descriptor)
{
    descriptor
        .Field(t => t.GetSessions())
        .UsePaging();
}
descriptor.Use(next => async context =>
{
    // logic
    
    await next(context);

    // more logic
})

https://chillicream.com

https://github.com/chillicream/hotchocolate