OData filtering on client-defined dynamic properties

Question

I have two entities defined in the server:

public partial class MyModel 
{
    public string ModelCode { get; set; }
    public virtual ICollection<MyModelSubItem> SubItems { get; set; } = new HashSet<MyModelSubItem>();
    [NotMapped]
    public IDictionary<string, object> DynamicProperties { get; set; }
}

public partial class MyModelSubItem
{
    public string SubItemCode { get; set; }
}

The controller has the following:

[EnableQuery]
public IQueryable<MyModel> Get()
{
    return _myModelContext.GetAll();
}

In the client, I extend MyModel:

public partial class MyModel 
{
    public int SubItemCount => SubItems.Count;
}

When I try to query the DB using the client-defined SubItemCount property, I get the following error

Query: /odata/v1/MyModel?$filter=true&$orderby=SubItemCount%20desc

Error: System.ArgumentException: Static property requires null instance, non-static property requires non-null instance. (Parameter 'instance')

Querying using the non-dynamic properties work fine. Even adding/patching work fine when requests include the dynamic properties. It's only filtering/sorting that isn't working.

I am using OData v4 and the Unchase OData client code generator.

I was wondering why this is case. Any help would be highly appreciated.

Answer 1

I solved the issue by using a custom EnableQuery attribute on the controller, as per the answer posted here:

.NET Core 2.1 OData v4 modify $filter on server side

public class MyModelEnableQueryAttribute : EnableQueryAttribute
{
    public override IQueryable ApplyQuery(IQueryable queryable, ODataQueryOptions queryOptions)
    {
        if (queryOptions.Filter != null)
        {
            var queryDict = new Dictionary<string, StringValues>();
            foreach (var queryKeyValPair in queryOptions.Request.Query)
            {
                var modifiedSingleQueryValues = new List<string>();
                foreach (var singleQueryValues in queryKeyValPair.Value)
                {
                    if (singleQueryValues.Contains("SubItemCount"))
                    {
                        modifiedSingleQueryValues.Add(singleQueryValues.Replace("SubItemCount", "SubItems/$count"));
                    }
                    else
                    {
                        modifiedSingleQueryValues.Add(singleQueryValues);
                    }
                }

                queryDict.Add(queryKeyValPair.Key, new StringValues(modifiedSingleQueryValues.ToArray()));
            }

            queryOptions.Request.Query = new QueryCollection(queryDict);
            queryOptions = new ODataQueryOptions(queryOptions.Context, queryOptions.Request);
        }

        return base.ApplyQuery(queryable, queryOptions);
    }
}

Controller:

[MyModelEnableQuery]
public IQueryable<MyModel> Get()
{
    return _myModelContext.GetAll();
}

This requires that the request includes $expand and $count on SubItems e.g.

/odata/v1/MyModel?$filter=true&$orderby=SubItemCount%20desc&$expand=SubItems($count=true)

Hopefully someone finds this useful if they come across the same problem as I did.