I’m using Hot Chocolate to query peoples:

using Microsoft.EntityFrameworkCore;

namespace SageApi.Model.Sage;

public partial class People
{
    public string Id { get; set; } = null!;

    public int? Age { get; set; }

    public string? Name { get; set; }


    public static void ConfigureModelBuilder(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<People>(entity =>
        {
            entity.HasIndex(e => e.Id, "UKA_PEOPLE_Id").IsUnique();
            entity.Property(e => e.Age).HasColumnName("Age");
            entity.Property(e => e.Name).HasColumnName("Name");
        });
    }
}

What I want to do ?

I want the people who use my API to be able to query the peoples who are over 21 years old without having to specify the age 21 (this is a simplify example of what I want to do, to keep it simple).

Something like:

{
    peoples(where: { aboveAge: { eq: true } }) {
        items {
            id
            age
            name
        }
    }
}

What I tried

So I added a field AboveAge in People like so (this way I can query this field even if this field doesn’t exists in the bdd):

using System.ComponentModel.DataAnnotations.Schema;
    // ...
    public string? Name { get; set; }
    
    [IsProjected(false)] [NotMapped] public virtual bool? AboveAge { get; set; }

    public static void ConfigureModelBuilder(ModelBuilder modelBuilder)
    // ...

In my Query.cs, I use UseOffsetPaging, UseProjection, UseFiltering, UseSorting and my custom UseAboveAgeFilter to modify the query before UseFiltering is called

public class Query
{
    [UseOffsetPaging(MaxPageSize = 100, IncludeTotalCount = true, DefaultPageSize = 20)]
    [UseProjection]
    [UseFiltering]
    [UseSorting]
    [UseAboveAgeFilter]
    public IEnumerable<People> GetPeoples([Service] AppDbContext context) =>
        context.Peoples;
}

In my UseAboveAgeFilter.cs:

using System.Reflection;
using System.Runtime.CompilerServices;
using HotChocolate.Types.Descriptors;
using SageApi.Model.Sage;

namespace SageApi.Services.GraphQl.Middleware;

public class UseAboveAgeFilterAttribute : ObjectFieldDescriptorAttribute
{
    public UseAboveAgeFilterAttribute([CallerLineNumber] int order = 0)
    {
        Order = order;
    }

    protected override void OnConfigure(
        IDescriptorContext context,
        IObjectFieldDescriptor descriptor,
        MemberInfo member
    )
    {
        descriptor.Use(next => async middlewareContext =>
        {
            // can I modify the middlewareContext in a way that I remove aboveAge param and replace it
            // with age >= 21, this way the UseFiltering Middleware will work as intended when it will
            // be called after ?
            await next(middlewareContext);
            object? result = middlewareContext.Result;
            if (result is InternalDbSet<People> dbSet)
            {
                // or can I do it here ?
            }
        });
    }
}

I want to modify the middlewareContext by removing the aboveAge = true condition and replace it with age >= 21 condition but I can’t find a way to it. If I can do that in my Middleware UseAboveAgeFilter which is call before all the Hot Chocolate Middleware it should work.

When I try to query I got error (which is normal, as I didn’t modify the middlewareContext to remove aboveAge = true condition and replace it with age >= 21):

{
    "errors": [
        {
            "message": "Unexpected Execution Error",
            "locations": [
                {
                    "line": 2,
                    "column": 5
                }
            ],
            "path": [
                "peoples"
            ],
            "extensions": {
                "message": "The LINQ expression 'DbSet<People>()rn    .Where(f => f.AboveAge == __p_0)' could not be translated. Additional information: Translation of member 'AboveAge' on entity type 'People' failed. This commonly occurs when the specified member is unmapped. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to 'AsEnumerable', 'AsAsyncEnumerable', 'ToList', or 'ToListAsync'. See https://go.microsoft.com/fwlink/?linkid=2101038 for more information.",
                "stackTrace": "   at Microsoft.EntityFrameworkCore.Query.QueryableMethodTranslatingExpressionVisitor.Translate(Expression expression)rn   at Microsoft.EntityFrameworkCore.Query.RelationalQueryableMethodTranslatingExpressionVisitor.Translate(Expression expression)rn   at Microsoft.EntityFrameworkCore.Query.QueryCompilationContext.CreateQueryExecutor[TResult](Expression query)rn   at Microsoft.EntityFrameworkCore.Storage.Database.CompileQuery[TResult](Expression query, Boolean async)rn   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.CompileQueryCore[TResult](IDatabase database, Expression query, IModel model, Boolean async)rn   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<>c__DisplayClass9_0`1.<Execute>b__0()rn   at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQuery[TResult](Object cacheKey, Func`1 compiler)rn   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.Execute[TResult](Expression query)rn   at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.Execute[TResult](Expression expression)rn   at System.Linq.Queryable.Count[TSource](IQueryable`1 source)rn   at HotChocolate.Types.Pagination.QueryableOffsetPagingHandler`1.<>c__DisplayClass3_0.<ResolveAsync>b__0()rn   at System.Threading.Tasks.Task`1.InnerInvoke()rn   at System.Threading.Tasks.Task.<>c.<.cctor>b__281_0(Object obj)rn   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)rn--- End of stack trace from previous location ---rn   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)rn   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)rn--- End of stack trace from previous location ---rn   at HotChocolate.Types.Pagination.QueryableOffsetPagingHandler`1.ResolveAsync(IResolverContext context, IQueryable`1 source, OffsetPagingArguments arguments, CancellationToken cancellationToken)rn   at HotChocolate.Types.Pagination.OffsetPagingHandler.HotChocolate.Types.Pagination.IPagingHandler.SliceAsync(IResolverContext context, Object source)rn   at HotChocolate.Types.Pagination.PagingMiddleware.InvokeAsync(IMiddlewareContext context)rn   at HotChocolate.Utilities.MiddlewareCompiler`1.ExpressionHelper.AwaitTaskHelper(Task task)rn   at SageApi.Services.GraphQl.Middleware.UseFDocenteteMappingAttribute.<>c__DisplayClass1_0.<<OnConfigure>b__1>d.MoveNext() in C:\Users\sagealexandrehome\Documents\SageApi\SageApi\Services\GraphQl\Middleware\UseFDocenteteMappingAttribute.cs:line 26rn--- End of stack trace from previous location ---rn   at HotChocolate.Execution.Processing.Tasks.ResolverTask.ExecuteResolverPipelineAsync(CancellationToken cancellationToken)rn   at HotChocolate.Execution.Processing.Tasks.ResolverTask.TryExecuteAsync(CancellationToken cancellationToken)"
            }
        }
    ],
    "data": {
        "peoples": null
    }
}

Question

Am I on the right path to solve this problem ?

If yes, how can I continue ?

If no, what can I try ?