EF 4.0 Dynamic Proxies POCO Object Does not match target type

I am using EF 4.0 and POCO's. I stumbled across this error while inserting to records into the data base.

Property accessor 'QualityReasonID' on object 'BI.Entities.QualityReason' threw the following exception:'Object does not match target type.'

There errors occur on the Databind to a GridView after saving a new record to the database. I identified what is happening but I am not sure WHY it is occurring or If I am using EF/POCO's incorrectly. Any insight would be appreciated.

The exception is occuring because the object types in the IEnumerable are not the same. The orginal entrys in the table are of type System.Data.Entity.DynamicProxies.QualityReason_E483AD567288B459706092F1825F53B1F93C65C5329F8095DD1D848B5D039F04} While the new one is BI.Entities.QuailtyReason.

Here is how I insert the new object.

   public void createQualityReason(QualityReason qReasons)
    {
        dbcontext.QualityReasons.AddObject(qReasons);
        dbcontext.SaveChanges();   
    }

I resolved the error by changing the fetch code from:

 public IEnumerable<QualityReason> fetchQualityReasons()
    {

        IEnumerable<QualityReason> queryReasons = dbcontext.QualityReasons.AsEnumerable();
        return queryReasons;
    }

to

 public IEnumerable<QualityReason> fetchQualityReasons()
    {

        IEnumerable<QualityReason> queryReasons = from data in dbcontext.QualityReasons.AsEnumerable()
                select new QualityReason
                {
                    QualityReasonID = data.QualityReasonID,
                    QualityReasonName = data.QualityReasonName
        开发者_高级运维        };
                    return queryReasons;
    }

So to get around the error I have to select into the POCO class explicitly each time. This feels like I am going something wrong. Any thoughts?

---

The error is caused because GridView does not handle polymorphic datasources when using boundfields. So you have two options

1. Use TemplateFields instead which can handle polymorphic datasources, this may changing some of your front end code and GridView events.

2. Use Linq to create a non-polymorphic databsource that the boundfields can handle

     So instead of using something like ti 
   
       gvGroups.DataSource = ProductHelper.Get()
       gvGroups.DataBind();
   
   
   
       var query = from p in ProductHelper.Get()
       select new {p.ProductId, p.ProductName, p.ProductDesc, p.ProductLink};
       gvGroups.DataSource = query;
       gvGroups.DataBind();
   

---

I don't know if the problem has been solved yet, but I've had the same problem with my (POCO) "Scenario" class.

The problem disappeared when using a context.CreateObject<Scenario> to create the (POCO) object i.s.o. a .... = new Scenario().

---

Faced the same issue today and used Value Injecter to solve it. It's as simple as:

var dynamicProxyMember = _repository.FindOne<Member>(m=>m.Id = 1);
var member = new Member().InjectFrom(dynamicProxyMember) as Member;

That's it :)