Hello,

I'm experiencing an issue where the data annotation validation attributes [StringLength] and [Range] are not enforced when using [GraphQLInputType] on input classes for mutations. However, these validation attributes work correctly when using [GraphQLArguments].

Environment:

EntityGraphQL.AspNet Version: 5.5.0
.NET Version: .NET 8
C# Version: C# 12

Details

1. Using [GraphQLInputType]:

[GraphQLInputType]
public class PersonMutationArgs
{
    [StringLength(5, ErrorMessage = "Person name must be less than 5 characters")]
    public string PersonName { get; set; } = default!;

    [Range(0, 100, ErrorMessage = "Age must be between 0 and 100")]
    public int Age { get; set; }
}

2. Using [GraphQLArguments]:

[GraphQLArguments]
public class PersonMutationFlatArgs
{
    [StringLength(5, ErrorMessage = "Person name must be less than 5 characters")]
    public string PersonName { get; set; } = default!;

    [Range(0, 100, ErrorMessage = "Age must be between 0 and 100")]
    public int Age { get; set; }
}

And the corresponding mutations:

public class PersonMutation : IGraphQlMutation
{
    [GraphQLMutation("Add a new person to the system")]
    public async Task<Expression<Func<EgDbContext, Person>>?> AddNewPerson(
        EgDbContext db, PersonMutationArgs args, IGraphQLValidator validator)
    {
        // Implementation omitted for brevity
    }

    [GraphQLMutation("Add a new person to the system")]
    public async Task<Expression<Func<EgDbContext, Person>>?> AddNewPersonFlat(
        EgDbContext db, PersonMutationFlatArgs args, IGraphQLValidator validator)
    {
        // Implementation omitted for brevity
    }
}

• With [GraphQLInputType]: When I use AddNewPerson and provide invalid inputs (e.g., a name longer than 5 characters or an age outside the range 0-100), the mutation does not produce validation errors. The person is incorrectly added to the database.

• With [GraphQLArguments]: When I use AddNewPersonFlat with the same invalid inputs, the validation works as expected, and the mutation returns the appropriate validation errors.

Expected Behavior:

Validation attributes like [StringLength] and [Range] should be enforced when using [GraphQLInputType], just as they are with [GraphQLArguments].

Reproduction:

I have prepared a minimal reproducible example demonstrating this issue. The code can be found here.

Also, adding it as a zip file here: EntityGraphQL_StringLength.zip

In the example, I've added two tests: one that uses [GraphQLInputType] and another that uses [GraphQLArguments]. While both pass, one of them is actually able to add data to the DB while it shouldn't due to a validation failure. The other one fails to add data to the DB as expected.