Hot Chocolate:
An Introduction to GraphQL for .NET

Michael Staib MVP


Demo

Ask for what you want

query {
  me {
    name
    feed {
      message
      from {
        name
      }
      images {
        title
        url
      }
    }
  }
}

Get what you asked for

{
  "data": {
    "me": {
      "name": "Michael Staib",
      "feed": {
        "message": "Have just arrived in Seattle for the Microsoft Build 2017 conference. Did some touristy stuff with Rafael Staib to stay awake and fight the jetlag :) I think we'll hit the bar now to have a little wine.",
        "from": {
          "name": "Michael Staib"
        },
        "images": {
          "title": "Wine Glass",
          "url": "http://facebook.com/images/44546654654876.png"
        }
      }
    }
  }
}

Get what you asked for

{
  "data": {
    "me": {
      "name": "Michael Staib",
      "feed": {
        "message": "Have just arrived in Seattle for the Microsoft Build 2017 conference. Did some touristy stuff with Rafael Staib to stay awake and fight the jetlag :) I think we'll hit the bar now to have a little wine.",
        "from": {
          "name": "Michael Staib"
        },
        "images": {
          "title": "Wine Glass",
          "url": "http://facebook.com/images/44546654654876.png"
        }
      }
    }
  }
}

query {
  me {
    name
    feed {
      message
      from {
        name
      }
      images {
        title
        url
      }
    }
  }
}

GET
https://webservices.amazon.com/onca/xml?

Service=AWSECommerceService&

AWSAccessKeyId=mY-Sup3r-s3cr3!-k3y&

AssociateTag=12345&  

Operation=ItemLookup&

ItemId=0316067938&

ResponseGroup=Reviews&

TruncateReviewsAt=256&

IncludeReviewsSummary=False&

Version=2013-08-01&

Timestamp=[YYYY-MM-DDThh:mm:ssZ]&

Signature=[Request Signature]

What is GraphQL?

GraphQL

Business Layer

Storage Layer

GraphQL

Rest
Services

gRPC
Services

...

Client

GraphQL

  • Single Source of Truth
  • One Endpoint
  • One Request
  • No over- or under- fetching (N+1)
  • Type System
  • Real-time

  • Predictability

GraphQL gives clients the power to ask for exactly what they need and nothing more.

Backend Engineer: Hmm. So you’re saying this “GraphQL” will allow any web or native engineer to arbitrarily query basically any field in any backend service, recursively, however they want, without any backend engineers involved?
 

Frontend Engineer: Yeah, right? It’s amazing!
 

[…silence…]
 

Backend Engineer: Guards, seize this person.

type Project {
  name: String!
  tagline: String
  contributors: [User] 
    @cost(complexity: 10)
}

Describe your data

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

 

Demo

What is GraphQL not?

  • Graph Database Query Language
  • Bound to a specific data source
  • Facebooks version of OData
  • Good solution for binary streams
  • Limited to HTTP
  • Limited to the JavaScript world


Demo

What about
Entity Framework?


Demo
 

query {
  students(where: { OR: [{ lastName: "Bar" }, { lastName: "Baz" }] }) {
    firstMidName
    lastName
    enrollments {
      course {
        title
      }
    }
  }
}
SELECT "s"."FirstMidName", "s"."LastName", "s"."Id", "t"."Title", 
       "t"."EnrollmentId", "t"."CourseId"
    FROM "Students" AS "s"
    LEFT JOIN (
        SELECT "c"."Title", "e"."EnrollmentId", "c"."CourseId", "e"."StudentId"
        FROM "Enrollments" AS "e"
        INNER JOIN "Courses" AS "c" ON "e"."CourseId" = "c"."CourseId"
    ) AS "t" ON "s"."Id" = "t"."StudentId"
    WHERE ("s"."LastName" = 'Bar') OR ("s"."LastName" = 'Baz')
    ORDER BY "s"."Id", "t"."EnrollmentId", "t"."CourseId"

Lets make it real-time


Demo

Conclusion

  • Iterate faster.
  • Request what you need get exactly that.
  • Fetch data more efficiently.
  • Takes away the complexity of data-fetching.

https://chillicream.com

https://github.com/chillicream/hotchocolate