Mapping GraphQL query to Select() linq to sql

Question

I am building an Web API with .NET core using GraphQL and DocumentDb.

In theory, GraphQL is optimized the data is shipped across the network and thus avoid over-fetching data. But I recognize that the backend server and database is doing the extra unnecessary work (query the entire document) when querying the database.

The best strategy here is using Select() to specific properties we need to fetch. But I have no idea how to build the expression from client's query that so complex.

Any help really appreciated.

Thanks

Answer 1

For translating linq-expressions to graphql-query you can use library: https://github.com/RDavydenko/SmartGraphQLClient

1. Install Nuget-package:

Install-Package SmartGraphQLClient

2. Add services to DI:

services.AddSmartGraphQLClient();

3. Use linq-syntax:

using SmartGraphQLClient;

GraphQLHttpClient client = ... // from DI

var users = await client.Query<UserModel>("users")
    .Include(x => x.Roles)
    .ThenInclude(x => x.Users)
    .Where(x => x.UserName.StartsWith("A") || x.Roles.Any(r => r.Code == RoleCode.ADMINISTRATOR))
    .Select(x => new 
    {
        x.Id,
        Name = x.UserName,
        x.Roles,
        IsAdministrator = x.Roles.Any(r => r.Code == RoleCode.ADMINISTRATOR)
    })
    .Skip(5)
    .Take(10)
    .Argument("secretKey", "1234")
    .ToListAsync();

Your request will be translated to graphql-query:

{ 
    users (
      where: {
        or: [ 
          { userName: { startsWith: "A" } }
          { roles: { some: { code: { eq: ADMINISTRATOR } } } }
        ]
      }
      skip: 5
      take: 10
      secretKey: "1234"
  ) {
        id
        userName
        roles {
            code
            name
            description
            id
            users {
                userName
                age
                id
            }
        }
    }
}