GraphQL–DotNet–Nullable types: Nullable<> cannot be coerced to a non nullable GraphQL type

I’m spending a lot (read: “waaay to many”) time learning GraphQL. One of the things I had to figure out was how to use nullable types inside my GraphQL schema.

By default when you use a nullable type inside your GraphQL schema, you get the following error message:

ArgumentOutOfRangeException: Explicitly nullable type: Nullable<DateTime> cannot be coerced to a non nullable GraphQL type.

To fix this, you have to expliclity specify the field as nullable in you GraphQL type definition:

	public class ProductType:ObjectGraphType<Product>
	{
	public ProductType()
	{
	Field(m => m.Id, type : typeof(IdGraphType));
	Field(m => m.Description);
	Field(m => m.NullableDate, nullable:true);
	}
	}

view raw ProductType.cs hosted with ❤ by GitHub