fiyazbinhasan / graphqlcore

Learn how to implement scalable APIs with GraphQL and ASP.NET Core. Branch wise code with relevant topic for smooth and easy walkthrough.

GraphQL with ASP.NET Core - A 10 Part Blog Series

This repository contains a series of posts with branch wise code on builing scalable GraphQL end-points with ASP.NET Core. Each branch has its own readme where you can find rach relevent post. You can also read the series from my blog,

http://fiyazhasan.me/tag/graphql-dotnet/

Ask anything you want in the comment section of my blog.

Running the application

• Download the zip or clone the project
• Make sure you have necessary dotnet core sdks installed (I'm using ASP.NET Core 2.1)

https://www.microsoft.com/net/download/windows

• Build and run the project

dotnet build dotnet run

Optional ( If you want a real database behind the scene )

• Make sure you have Postgres installed in your system

https://postgresapp.com/

• Change the connection string in appsettings.json to target your local posgres database.
• From command line go to the root of the project and create a db migration script

dotnet ef migrations add Initial -o Data/Migrations

• Apply migration in your database

dotnet ef database update

Branches

Part I - Hello World

Part II - Middleware

Part III - Dependency Injection

Part IV - GraphiQL - An in-browser IDE

Part V - Fields, Arguments, Variables

Part VI - Persist Data - Postgres with EF Core

Part VII - Mutation

Part VIII - Entity Relations - One to Many

Part IX - Entity Relations - Many to Many

Part X - Data Loader

Video Tutorials

Coming Soon...

Mentions

Joe McBride - Thanks for providing an awesome community driven project

graphql-dotnet

Jon Galloway - Thanks for featuring posts on ASP.NET Community Standup

graphqlcore's Issues

Link to graphql dotnet broken

Link at bottom of this page:

https://github.com/fiyazbinhasan/GraphQLCore/tree/Part_X_DataLoader

is currently: https://graphql-dotnet.github.io/dataloader/
should be: https://graphql-dotnet.github.io/docs/guides/dataloader/

Part X - Dataloader - Many to many

This works great but how to do many to many with the dataLoader?

Lets say i want to fetch the companies with there contacts (and a contact can have multiple companies).
I have a companyLinks as midde table (with companyId/contactId).

I have this which works when there is only 1 contact for a company:

public async Task<ILookup<Guid, Contact>> GetContactsFromCompanyBatchAsync(IEnumerable<Guid> companyIds)    
{
  var contacts = _entities.Include(c => c.CompanyLinks).Where(contact => contact.CompanyLinks.Any(cl => companyIds.Contains(cl.CompanyId)));
  return contacts.ToLookup(cont => {
       var res = cont.CompanyLinks.Any() ? cont.CompanyLinks.ElementAt(0).CompanyId : Guid.Empty;
       return res;
  });
}

But what if a contact has more then 1 company? How can i know the correct companyId ?

stackoverflow

implementing with mssql

How different would this implementation be with a mssql connection instead of postgres?