what is wrong with this insert method in asp.net mvc?

My controller calls a repository class method on insert,

 [AcceptVerbs(HttpVerbs.Post)]
        public ActionResult Create([Bind(Exclude = "Id")]FormCollection collection)
        {
            try
            {
                MaterialsObj materialsObj = new MaterialsObj();
                materialsObj.Mat_Name = collection["Mat_Name"];
                materialsObj.Mes_Id = Convert.ToInt64(collection["MeasurementType"]);
                materialsObj.Mes_Name = collection["Mat_Ty开发者_如何学运维pe"];
                materialsObj.CreatedDate = System.DateTime.Now;
                materialsObj.CreatedBy = Convert.ToInt64(1);
                materialsObj.IsDeleted = Convert.ToInt64(1);
                consRepository.createMaterials(materialsObj);

                return RedirectToAction("Index");
            }
            catch
            {
                return View();
            }
        }

and my repository class has this,

public MaterialsObj createMaterials(MaterialsObj materialsObj)
{
    db.Materials.InsertOnSubmit(materialsObj);
    return materialsObj;
}

But when i compile this i get The best overloaded method match for 'System.Data.Linq.Table<CrMVC.Models.Material>.InsertOnSubmit(CrMVC.Models.Material)' has some invalid arguments... cannot convert from 'CrMVC.BusinessObjects.MaterialsObj' to 'CrMVC.Models.Material'..

am i missing something?

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The object you pass to InsertOnSubmit has to be one of your LINQ-to-SQL Classes.

In this case, you're trying to insert an Object of a type that LINQ-to-SQL has no idea about (one of your business objects, not a LINQ-to-SQL type).

There are several ways to overcome this. Once is to convert the business object to the appropriate LINQ-to-SQL class in your Repository. The other is to create an implicit cast between the two and let .NET handle the rest.

Repository Cast Code

public MaterialsObj createMaterials(MaterialsObj materialsObj)
{
    CrMVC.Models.Material mat = new CrMVC.Models.Material();

    // copy properties to the Materials object from materialsObj
    db.Materials.InsertOnSubmit(mat);

    materialsObject.IdField = mat.IdField;

    return materialsObj;
}

Implicit Cast Code (method added to the Business Object class)

public static implicit operator CrMVC.Models.Material
    (CrMVC.BusinessObjects.MaterialsObj)
{
    // Add conversion code here
}

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you might want to add db.SubmitChanges() to commit the changes