Code Analyzers for better Development Experience

[PascalSenn]

We want to introduce analyzers that help avoiding common misstakes

Parent of different kind than extensions

Good✅

[ExtendObjectType(typeof(Bar))]
public class FoosBarExtensions
{
    public Task<Foo?> GetFooAsync(
        [Parent] Bar api,
        [Service] IGetFooService service,
        CancellationToken cancellationToken)
        => service.GetByBarIdAsync(api.Id, cancellationToken);
}

Bad❌

[ExtendObjectType(typeof(Bar))]
public class FoosBarExtensions
{
    public Task<Foo?> GetFooAsync(
        [Parent] ThisIsTheWrongType api, //<--- WARNING: The parent type is not equal to the type of the extension
        [Service] IGetFooService service,
        CancellationToken cancellationToken)
        => service.GetByBarIdAsync(api.Id, cancellationToken);
}

Middleware Ordering

Good✅

public class FooType : ObjectType<Foo>
{
    protected override void Configure(IObjectTypeDescriptor<Foo> descriptor)
    {
        descriptor.Field(x => x.Bars)
               .UsePaging()
               .UseProjections()
               .UseFiltering()
               .UseSorting();
    }

public class Foo
{
     [UsePaging]
     [UseProjections]
     [UseFiltering]
     [UseSorting]
     public Bar[] Bars {get:}
}

Bad❌

[ExtendObjectType(typeof(Bar))]
public class FooType : ObjectType<Foo>
{
    protected override void Configure(IObjectTypeDescriptor<Foo> descriptor)
    {
        descriptor.Field(x => x.Bars)
               .UsePaging()
               .UseSorting()
               .UseProjections() //<--- WARNING: UseProjections should not be chained after Sorting
               .UseFiltering();
    }
}

public class Foo
{
     [UsePaging]
     [UseFiltering]
     [UseProjections] //<--- WARNING: UseProjections should not be chained after Sorting
     [UseSorting]
     public Bar[] Bars {get:}
}

UseRequest without UseDefaultPipeline

Good✅

  services.AddGraphQLServer()
       // ...
       .UseRequest(n => async c => await n(c))
       .UseDefaultPipeline();

Bad ❌

  services.AddGraphQLServer()
       // ...
       .UseRequest(n => async c => await n(c)); /// <--- WARNING: UseRequest without UseDefaultPipeline will lead to a invalid pipeline

Only use optional when it makes sense

Good✅

  public Optional<string?> Foo {get;set;}
 
  [DefaultValue("")]
  public Optional<string> Foo {get;set;}

Bad ❌

  public Optional<string> Foo {get;set;}