The best way to modify a WebAPI OData QueryOptions.Filter - asp.net-web-api

Question

I am using the OData sample project at http://www.asp.net/web-api/overview/odata-support-in-aspnet-web-api/working-with-entity-relations. In the Get I want to be able to change the Filter in the QueryOptions of the EntitySetController:
public class ProductsController : EntitySetController<Product, int>
{
ProductsContext _context = new ProductsContext();
[Queryable(AllowedQueryOptions=AllowedQueryOptions.All)]
public override IQueryable<Product> Get()
{
var products = QueryOptions.ApplyTo(_context.Products).Cast<Product>();
return products.AsQueryable();
}
I would like to be able to find properties that are specifically referred to. I can do this by parsing this.QueryOptions.Filter.RawValue for the property names but I cannot update the RawValue as it is read only. I can however create another instance of FilterQueryOption from the modified RawValue but I cannot assign it to this.QueryOptions.Filter as this is read only too.
I guess I could call the new filter's ApplyTo passing it _context.Products, but then I will need to separately call the ApplyTo of the other properties of QueryOptions like Skip and OrderBy. Is there a better solution than this?
Update
I tried the following:
public override IQueryable<Product> Get()
{
IQueryable<Product> encryptedProducts = _context.Products;
var filter = QueryOptions.Filter;
if (filter != null && filter.RawValue.Contains("Name"))
{
var settings = new ODataQuerySettings();
var originalFilter = filter.RawValue;
var newFilter = ParseAndEncyptValue(originalFilter);
filter = new FilterQueryOption(newFilter, QueryOptions.Context);
encryptedProducts = filter.ApplyTo(encryptedProducts, settings).Cast<Product>();
if (QueryOptions.OrderBy != null)
{
QueryOptions.OrderBy.ApplyTo<Product>(encryptedProducts);
}
}
else
{
encryptedProducts = QueryOptions.ApplyTo(encryptedProducts).Cast<Product>();
}
var unencryptedProducts = encryptedProducts.Decrypt().ToList();
return unencryptedProducts.AsQueryable();
}
and it seems to be working up to a point. If I set a breakpoint I can see my products in the unencryptedProducts list, but when the method returns I don't get any items. I tried putting the [Queryable(AllowedQueryOptions=AllowedQueryOptions.All)] back on again but it had no effect. Any ideas why I am not getting an items?
Update 2
I discovered that my query was being applied twice even though I am not using the Queryable attribute. This meant that even though I had items to return the List was being queried with the unencrypted value and therefore no values were being returned.
I tried using an ODataController instead:
public class ODriversController : ODataController
{
//[Authorize()]
//[Queryable(AllowedQueryOptions = AllowedQueryOptions.All)]
public IQueryable<Products> Get(ODataQueryOptions options)
{
and this worked! Does this indicate that there is a bug in EntitySetController?

Answer 1

You would probably need to regenerate ODataQueryOptions to solve your issue. Let's say if you want to modify to add $orderby, you can do this like:
string url = HttpContext.Current.Request.Url.AbsoluteUri;
url += "&$orderby=name";
var request = new HttpRequestMessage(HttpMethod.Get, url);
ODataModelBuilder modelBuilder = new ODataConventionModelBuilder();
modelBuilder.EntitySet<Product>("Product");
var options = new ODataQueryOptions<Product>(new ODataQueryContext(modelBuilder.GetEdmModel(), typeof(Product)), request);