GraphQL C#

dotnet add package graphiql --version=2.0.0
dotnet add package GraphQL --version=4.6.1
dotnet add package GraphQL.Server.Transports.AspNetCore.SystemTextJson --version=5.2.2
dotnet add package GraphQL.Server.Ui.GraphiQL --version=5.2.2

public class CategoryType : ObjectGraphType{
    public CategoryType(){
        Field(p => p.CategoryId, type: typeof(IdGraphType)).Description("Id Property for Category object");
        Field(p => p.CategoryName, type: typeof(StringGraphType)).Description("Name Property for Category object");
    }
}

public class CategoryInputType : InputObjectGraphType{
    public CategoryInputType(){
        Name = "CategoryInputType";
        Field<StringGraphType>("CategoryName");
    }
}

public class CategoryQuery : ObjectGraphType<Category>{
    public CategoryQuery(CategoryRepository repository){
        Field<ListGraphType<CategoryType>(
            name: "categories", 
            resolve: context => repository.GetCategories());
        Field<CategoryType>(
            name: "category", 
            arguments: new QueryArguments(
                new QueryArgument<NonNullGraphType<IntGraphType>>{ Name = "id", Description = "Category Id"}),
            resolve: p => repository.GetCategory(p.GetArgument<short>("id")));
    }
}

public class CategoryMutation : ObjectGraphType{
    public CategoryMutation(CategoryRepository repository){
        Field<CategoryType>(
            name: "addCategory",
            arguments: new QueryArguments(
                new QueryArgument<NonNullGraphType<CategoryInputType>>{ 
                    Name = "category", 
                    Description = "Category input parameter"}
            ),
            resolve: p => {
                var obj = p.GetArgument<Category>("category");
                if(obj != null){
                    return repository.Add(obj);
                }
                return -1;
            });
    }
}

public class AppSchema : Schema{
    public AppSchema(CategoryQuery query, CategoryMutation mutation) => 
        (Query, Mutation) = (query, mutation);
}

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddGraphQL().AddSystemTextJson();
builder.Services.AddControllers();
var app = builder.Build();
app.UseGraphQL();
app.UseGraphQLGraphiQL("/ui/graphql");
app.MapControllers();