I am trying to write some generic LINQ queries for my entities, but am having issue doing the more complex things. Right now I am using an EntityDao class that has all my generics and each of my object class Daos (such as Accomplishments Dao) inherit it, am example:

using LCFVB.ObjectsNS;
using LCFVB.EntityNS;

namespace AccomplishmentNS
{
  public class AccomplishmentDao : EntityDao<Accomplishment>{}
}

Now my entityDao has the following code:

using LCFVB.ObjectsNS;
using LCFVB.LinqDataContextNS;

namespace EntityNS
{
public abstract class EntityDao<ImplementationType> where ImplementationType : Entity
{
public ImplementationType getOneByValueOfProperty(string getProperty, object getValue)
{ 
  ImplementationType entity = null;
         if (getProperty != null && getValue != null) {
            //Nhibernate Example:
            //ImplementationType entity = default(ImplementationType);
            //entity = Me.session.CreateCriteria(Of ImplementationType)().Add(Expression.Eq(getProperty, getValue)).UniqueResult(Of InterfaceType)()

            LCFDataContext lcfdatacontext = new LCFDataContext();

            //Generic LINQ Query Here
            lcfdatacontext.GetTable<ImplementationType>();


            lcfdatacontext.SubmitChanges();

            lcfdatacontext.Dispose();
        }


        return entity;
    }

    public bool insertRow(ImplementationType entity)
    {
        if (entity != null) {
            //Nhibernate Example:
            //Me.session.Save(entity, entity.Id)
            //Me.session.Flush()

            LCFDataContext lcfdatacontext = new LCFDataContext();

            //Generic LINQ Query Here
            lcfdatacontext.GetTable<ImplementationType>().InsertOnSubmit(entity);

            lcfdatacontext.SubmitChanges();
            lcfdatacontext.Dispose();

            return true;
        }
        else {
            return false;
        }
    }

}

}

            I have gotten the insertRow function working, however I am not even sure how to go about doing getOnebyValueOfProperty, the closest thing I could find on this site was:

http://stackoverflow.com/questions/2157560/generic-linq-to-sql-query

How can I pass in the column name and the value I am checking against generically using my current set-up? It seems like from that link it's impossible since using a where predicate because entity class doesn't know what any of the properties are until I pass them in.

Lastly, I need some way of setting a new object as the return type set to the implementation type, in nhibernate (what I am trying to convert from) it was simply this line that did it:

  ImplentationType entity = default(ImplentationType);

However default is an nhibernate command, how would I do this for LINQ?

EDIT:

getOne doesn't seem to work even when just going off the base class (this is a partial class of the auto generated LINQ classes). I even removed the generics. I tried:

namespace ObjectsNS
{    
    public partial class Accomplishment
     {
       public Accomplishment getOneByWhereClause(Expression<Action<Accomplishment, bool>> singleOrDefaultClause)
     {
        Accomplishment entity = new Accomplishment();
         if (singleOrDefaultClause != null) {
              LCFDataContext lcfdatacontext = new LCFDataContext();

                 //Generic LINQ Query Here
              entity = lcfdatacontext.Accomplishments.SingleOrDefault(singleOrDefaultClause);

               lcfdatacontext.Dispose();
               }
            return entity;
               }
          }
      }

Get the following error:

Error   1   Overload resolution failed because no accessible 'SingleOrDefault' can be called with these arguments:
Extension method 'Public Function SingleOrDefault(predicate As System.Linq.Expressions.Expression(Of System.Func(Of Accomplishment, Boolean))) As Accomplishment' defined in 'System.Linq.Queryable': Value of type 'System.Action(Of System.Func(Of LCFVB.ObjectsNS.Accomplishment, Boolean))' cannot be converted to 'System.Linq.Expressions.Expression(Of System.Func(Of LCFVB.ObjectsNS.Accomplishment, Boolean))'.
Extension method 'Public Function SingleOrDefault(predicate As System.Func(Of Accomplishment, Boolean)) As Accomplishment' defined in 'System.Linq.Enumerable': Value of type 'System.Action(Of System.Func(Of LCFVB.ObjectsNS.Accomplishment, Boolean))' cannot be converted to 'System.Func(Of LCFVB.ObjectsNS.Accomplishment, Boolean)'.     14  LCF

Okay no problem I changed:

public Accomplishment getOneByWhereClause(Expression<Action<Accomplishment, bool>> singleOrDefaultClause)

to:

public Accomplishment getOneByWhereClause(Expression<Func<Accomplishment, bool>> singleOrDefaultClause)

Error goes away. Alright, but now when I try to call the method via:

Accomplishment accomplishment = new Accomplishment();
var result = accomplishment.getOneByWhereClause(x=>x.Id = 4)

It doesn't work it says x is not declared.

I also tried getOne, and various other Expression

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