How to mutate a list of custom objects in GraphQL for .NET

Question

Using GraphQL for .NET, I would like to replace the collection of Foo with a new collection.

Given this server-side code:

public class Foo
{
    public Foo(string name)
    {
        Name = name;
    }

    public string Name { get; set; }
}

public class Root
{
    public Foo[] Foos { get; private set; }

    public Foo[] UpdateFoos(Foo[] foos)
    {
        Foos = foos;
        return Foos;
    }
}

public class MutationSchema : Schema
{
    public MutationSchema()
    {
        Query = new MutationQuery();
        Mutation = new MutationChange();
    }
}

public class FooType : ObjectGraphType
{
    public FooType()
    {
        Name = "IndividualFoo";
        Field<StringGraphType>("name");
    }
}

public class FoosType : ObjectGraphType<ListGraphType<FooType>>
{
    public FoosType()
    {
        Name = "ListOfFoo";
        Field<ListGraphType<FooType>>("foos");
    }
}

public class FoosInput : InputObjectGraphType
{
    public FoosInput()
    {
        Name = "InputForManyFoo";
        Field<ListGraphType<FooInput>>("foos");
        Field<ListGraphType<FooType>>("foosResult");
    }
}

public class FooInput : InputObjectGraphType
{
    public FooInput()
    {
        Name = "InputForSingleFoo";
        Field<StringGraphType>("name");
    }
}

public class MutationQuery : ObjectGraphType
{
    public MutationQuery()
    {
        Name = "Query";
        Field<FoosType>("queryAllFoos");
    }
}

public class MutationChange : ObjectGraphType
{
    public MutationChange()
    {
        Name = "Mutation";

        Field<FoosInput>(
            "updateAllFoos",
            arguments: new QueryArguments(
                new QueryArgument<FoosInput>
                {
                    Name = "updateFoosQueryArgument"
                }
            ),
            resolve: context =>
            {
                var root = context.Source as Root;
                var change = context.GetArgument<Foo[]>("updateFoosQueryArgument");
                // TODO: update collection e.g. return root.UpdateFoos(change);
                return change;
            }
        );
    }
}

When I run the mutation query:

mutation M {
    fooCollection: updateAllFoos(updateFoosQueryArgument: {
        foos: [
            {name: "First Foo"},
            {name: "Second Foo"}
        ]}) {
        foosResult
    }
}

Then I get the following error:

{GraphQL.Validation.ValidationError: Cannot query field "foosResult" on type "InputForManyFoo". Did you mean "foosResult"?}

I'm using the latest version of GraphQL for .NET at the time of writing.

What am I missing?

---

Working Example: How to mutate a list of custom objects in GraphQL for .NET

Answer 1

My answer from Gitter.

Make an ObjectGraphType for the result. Notice that the “shape” of the object that is returned from resolve matches the “shape” of the graph type.

public class FoosResultType : ObjectGraphType
{
    public FoosResultType()
    {
        Field<ListGraphType<FooType>>("foosResult");
    }
}

public class FoosResult
{
    public IEnumerable<Foo> FoosResult { get;set; }
}

public class MutationChange : ObjectGraphType
{
    public MutationChange()
    {
        Name = "Mutation";

        Field<FoosResultType>(
            "updateAllFoos",
            arguments: new QueryArguments(
                new QueryArgument<ListGraphType<FooInput>>
                {
                    Name = "updateFoosQueryArgument"
                }
            ),
            resolve: context =>
            {
                var root = context.Source as Root;
                var change = context.GetArgument<List<Foo>>("updateFoosQueryArgument");
                // TODO: update collection e.g. return root.UpdateFoos(change);
                return new FoosResult { FoosResult = change };
            }
        );
    }
}

And updated mutation:

mutation M {
    fooCollection: updateAllFoos(updateFoosQueryArgument: [
          {name: "First Foo"},
          {name: "Second Foo"}
        ]) {
        foosResult {
          name
        }
    }
}