GraphQL.EntityFrameworkCore.Helpers 0.5.2

GraphQL Helpers for EF Core

Adds methods to resolve schema fields directly from a DbContext.

Getting Started

dotnet add package GraphQL.EntityFrameworkCore.Helpers

And edit Startup.cs to register dependencies by calling method below in ConfigureServices(IServiceCollection services):

services
    .AddGraphQLEntityFrameworkCoreHelpers();

Defining the Schema

To resolve a root query from a DbContext using the helper methods you first need to define from what DbContext and what DbSet and then call either the ResolveCollectionAsync method or the ResolvePropertyAsync method.

Field<ListGraphType<HumanGraphType>>()
    .Name("Humans")
    .From(dbContext, x => x.Humans)
    .ResolveCollectionAsync();

You can also add connections in a similar way. With the connections the client has the option to define what property/properties should be used to order the connection with. Read more about connections here.

Connection<DroidGraphType>()
    .Name("Droids")
    .From(dbContext, x => x.Droids)
    .ResolveAsync();

The helper methods can also be used to resolve data loaded properties. Read more about data loaded fields here.

Field<PlanetGraphType, Planet>()
    .Name("HomePlanet")
    .Include(dbContext, x => x.HomePlanet)
    .ResolveAsync();

Applying business logic when resolving fields

With all builders you can apply your own business logic to for instance support multi-tenant solutions using the method Apply.

Field<PlanetGraphType, Planet>()
    .Name("HomePlanet")
    .Include(dbContext, x => x.HomePlanet)
    .Apply((query, context) =>
    {
        var id = context.GetArgument<int>("id");
        return query.Where(x => x.Id == id);
    })
    .ResolveAsync();

Validating the context

Similarly you can validate the arguments passed to a context using either the Validate method or the ValidateAsync method.

Field<PlanetGraphType, Planet>()
    .Name("HomePlanet")
    .Include(dbContext, x => x.HomePlanet)
    .ValidateAsync(async context =>
    {
        var result = new ValidationResult();
        var hasAccess = await UserValidator.HasAccessTo(context.GetArgument<int>("id"));

        if (hasAccess == false)
        {
            result.failures.Add(new ValidationFailure("id", "No access"));
        }

        return result;
    }))
    .Apply((query, context) => query.Where(x => x.Id == context.GetArgument<int>("id")))
    .ResolveAsync();

Filters

All collection fields can be filtered by either applying a string to all filterable properties using Or or applying specific rules for specific properties. Read more about filters here.

Avoiding Over-Fetching

All helper methods tries to limit the amount data fetched from data store by looking at what was requested, read more about this here.

Requirements

Requires GraphQL for .NET Server minimum version 4.0 or that ExecutionOptions.RequestServices is defined when calling ExecuteAsync.