In GraphQL HotChocolate can you have optional parameters or use a constructor?

Question

I am using HotChocolate as a GraphQL server from my ASP.NET Core Api . The parameters of a request need to have an optional parameter, a Guid, however if the Guid is null then the model needs to generate a random Guid.

public class MutationType : ObjectType<Mutation> {
  protected override void Configure(IObjectTypeDescriptor<Mutation> desc) 
  {
    desc
      .Field((f) => f.CreateAction(default))
      .Name("createAction");
  }
}

The class Mutation has the following method.

public ActionCommand CreateAction(ActionCommand command) {
  ...
  return command;
}

The ActionCommand class looks like this:

public class ActionCommand {
  public Guid Id { get; set; }
  public string Name { get; set; }

  public ActionCommand(string name, Guid id = null) {
    Name = name;
    Id = id ?? Guid.NewGuid()
  }
}

This command is the problem in question. I want to be able to use this logic for the Id property in GraphQL, the documentation isn't clear (to my eyes), can anyone shed some light on this?

Thanks!

Answer 1

The solution to this problem was creating an abstract base CommandType like so:

public abstract class CommandType<TCommand> : InputObjectType<TCommand> 
    where TCommand : Command {
  protected override void Configure(IInputObjectTypeDescriptor<TCommand> desc) {
    desc.Field(f => f.CausationId).Ignore();
    desc.Field(f => f.CorrelationId).Ignore();
  }
}

Then have the custom Input types inherit this class like so:

public class SpecificCommandType : CommandType<SpecificCommand> {
   protected override void Configure(IInputObjectTypeDescriptor<SpecificCommand> desc) {
      base.Configure(desc);
      desc.Field(t => t.Website).Type<NonNullType<UrlType>>();
   }
}

Or the short hand if no further configuring is needed.

public class SpecificCommandType : CommandType<SpecificCommand> { }

The commands themselves derive from the Command class which generates a Guid for the values as needed.

public abstract class Command {
  protected Command(Guid? correlationId = null, Guid? causationId = null) {
    this.CausationId = this.CorrelationId = Guid.NewGuid();
  }

  public Guid CausationId { get; set; }
  public Guid CorrelationId { get; set; }
}