How do we hookup a custom IQueryable logic to the filter/sort configurations?

[gojanpaolo]

We have a few use cases that will need custom IQueryable logic for filtering/sorting.
For example, given the following models:

public class Time
{
    public DateTime? In { get; set; }
    public DateTime? Out { get; set; }
}
public class Employee
{
    public ICollection<Time> Times { get; } = new HashSet<Time>();
}
public enum Status
{
    In,
    Out
}

We'd like the client to be able to do

query { employees(where: { status: { eq: IN } }) }

I started with the following FilterInputType configuration but I'm currently lost on the next steps.

public class EmployeeFilterInputType : FilterInputType<Employee>
{
    protected override void Configure(IFilterInputTypeDescriptor<Employee> descriptor)
    {
        descriptor
            .Field("status")
            .Type<EnumType<Status>>()
            .Extend()
            .OnBeforeCreate(_ => _.Handler = new StatusHandler());
    }

    public class StatusHandler : IFilterFieldHandler
    {
        public bool CanHandle(ITypeCompletionContext context, IFilterInputTypeDefinition typeDefinition, IFilterFieldDefinition fieldDefinition)
            => throw new NotImplementedException();

        // TODO: hook this logic to the filter
        public IQueryable<Employee> Handle(
            IQueryable<Employee> employees,
            Status status) =>
            status == Status.In
            ? employees.Where(_ => _.Times.OrderByDescending(_ => _.Out ?? _.In).First().Out == null)
            : employees.Where(_ => _.Times.OrderByDescending(_ => _.Out ?? _.In).First().Out != null);
    }
}

I'll continue looking into this and post my solution if I'm able to solve it but any help would be greatly appreciated! Thanks!

[michaelstaib]

You are lost in how to apply the FilterInput types or what is your exact issue?

[gojanpaolo]

@michaelstaib I'm lost on how to apply the following method to handle where: { status: { eq: ... } }.

public IQueryable<Employee> Handle(
    IQueryable<Employee> employees,
    Status status) =>
    status == Status.In
    ? employees.Where(_ => _.Times.OrderByDescending(_ => _.Out ?? _.In).First().Out == null)
    : employees.Where(_ => _.Times.OrderByDescending(_ => _.Out ?? _.In).First().Out != null);

As shown on my sample on my first post, I'm trying to use Extend().OnBeforeCreate(_ => _.Handler = new StatusHandler().. StatusHandler then implements IFilterFieldHandler but I'm not sure where to go from there... I'm also not sure yet if using Extend().OnBeforeCreate is the correct way to start.

[gojanpaolo]

I think I got it.. Basically, there is a QueryableDefaultFieldHandler that we can inherit and override TryHandleEnter instead of implementing IFilterFieldHandler..

Everything stays the same with the sample on first post above except for the StatusHandler implementation which is now:

public class StatusHandler : QueryableDefaultFieldHandler
{
    public override bool TryHandleEnter(QueryableFilterContext context, IFilterField field, ObjectFieldNode node, [NotNullWhen(true)] out ISyntaxVisitorAction? action)
    {
        Expression<Func<Employee, bool>> expression =
            (string)node.Value.Value! == "IN"
            ? _ => _.Times.OrderByDescending(_ => _.Out ?? _.In).First().Out == null
            : _ => _.Times.OrderByDescending(_ => _.Out ?? _.In).First().Out != null;
        var invoke = Expression.Invoke(expression, context.GetInstance());
        context.GetLevel().Enqueue(invoke);
        action = SyntaxVisitor.SkipAndLeave;
        return true;
    }
}