How did I wrong my DataContext?

问题

I've been working with LINQ To SQL for some time now, and what I usually do in a solution is the following:

In a project I create a dbml schema.
In another project I create a simple DataAccessLayer (DAL) that knows my first project, and instantiates a DataContext.
In the 3rd project (Business logic) I instantiate my DAL.

This usually works well. However, this time, I don't know why, but "It" doesn't work. "It" being "Me updating the database". I changed my code around to do some tests, and I get a result I don't understand.

MyDataContext dataContext = new MyDataContext(MyConnectionString);
DataBaseItem dbi = (from item in dataContext.DataBaseItems
    where item.ID == 1
    select item).First();
dbi.Name= "toto";
// dataContext.GetChangeSet() tells me nothing changed.

I dug deeper by breaking into the bdi.Name = "toto"; and compared it with a similar value assignment in a project where it works (both are designer generated code) and saw that some code was missing (I wrote them down there, but I commented them so you see what is missing) :

[Column(Storage="_Name", DbType="NVarChar(250)")]
public string Name
{
    get
    {
        return this._Name;
    }
    set
    {
        if ((this._Name!= value))
        {
            //this.OnLayoutChanging(value);
            //this.SendPropertyChanging();
            this._Name= value;
            //this.SendPropertyChanged("Name");
            //this.OnLayoutChanged();
        }
    }
}

Anyone can tell me how come these lines are missing, and where did I messed up?

When I do dataContext.Refresh(RefreshMode.KeepChanges, dataContext.DataBaseItems);, I get an error:

An object specified for refresh is not recognized.

回答1:

If your objects do not have a primary key, then the objects will not be tracked for changes. It is probable ID was not set as primary key in the dbml.

回答2:

The error was within the IDE (VS2008). The generation, or regeneration, of any Linq-to-Sql object by the IDE was faulty. To fix the problem, I had to :

Remove the objects that were erroneous.
Close Visual Studio.
Reopen Visual Studio.
Recreate the objects.

Not doing the first stop and instead have the object regenerated by changing a parameter could have worked, but I can't test it, since I don't know how to reproduce the problem.

来源：https://stackoverflow.com/questions/4187167/how-did-i-wrong-my-datacontext

标签

linq-to-sql

datacontext