Question

I am having some issues with using the OrderBy extension method on a LINQ query when it is operating on an enum type. I have created a regular DataContext using visual studio by simply dragging and dropping everything onto the designer. I have then created seperate entity models, which are simply POCO’s, and I have used a repository pattern to fetch the data from my database and map them into my own entity models (or rather, I have a repository pattern, that builds up and IQueryable that’ll do all this).

Everything works just fine, except when I try to apply an OrderBy (outside of the repository) on a property that I have mapped from short/smallint to an enum.

Here are the relevant code bits:

public class Campaign {     public long Id { get; set; }     public string Name { get; set; }     ....     public CampaignStatus Status { get; set; }     ... } public enum CampaignStatus : short {     Active,     Inactive,     Todo,     Hidden } public class SqlCampaignRepository : ICampaignRepository { ...     public IQueryable<Campaign> Campaigns()     {         DataContext db = new DataContext();         return from c in db.Campaigns                 select new Campaign                    {                        Id = c.Id,                        Name = c.Name,                        ...                        Status = (CampaignStatus)c.Status,                        ...                    };      } } 

And then elsewhere

SqlCampaignRepository rep = new SqlCampaignRepository(); var query = rep.Campaigns().OrderBy(c => c.Status); 

This triggers the following exception: System.ArgumentException was unhandled by user code Message=’The argument ‘value’ was the wrong type. Expected ‘IQMedia.Models.CampaignType’. Actual ‘System.Int16′.’ Source=’System.Data.Linq’ StackTrace: ved System.Data.Linq.SqlClient.SqlOrderExpression.set_Expression(SqlExpression value) ved System.Data.Linq.SqlClient.SqlBinder.Visitor.VisitSelect(SqlSelect select) ved System.Data.Linq.SqlClient.SqlVisitor.Visit(SqlNode node) ved System.Data.Linq.SqlClient.SqlBinder.Visitor.VisitIncludeScope(SqlIncludeScope scope) …

(sorry about the danish in there, ved = by/at).

I have tried typecasting the Status to short in the orderBy expression, but that doesn’t help it, same if i cast it to the actual enum type as well.

Any help fixing this is greatly appreciated!

Answer 1

Can you specify the type CampaignStatus directly in your DataContext trough the designer? This way the value is automatically mapped to the enum.