LINQ To SQL error "There is already an open DataReader associated with this Command"

There is already an open DataReader associated with this Command

I am getting this开发者_如何学Go error when I retrieve data from the DataContext object.

How can this be fixed?

---

Ensure that you're not declaring your DataContext as static. Create and destroy your DataContext on each use.

public MyDataClass{

    CustomerDataContext db;

    public void MyDataClass()
    {
       db = new CustomerDataContext();
    }

    public Customer GetCustomer(int id)
    {
       return db.Customers.SingleOrDefault(c=>c.ID == id);
    }
} 

---

Check this post

Is mixing ADO.NET and LINQ-TO-SQL bad? My data layer isn't working

It realy depends how you store, access and dispose the datacontext. Try to reproduce the error using a load test tool. I use jmeter. Lots of people don't know that they have this issue, because they have too little traffic.

---

You have forget to close the DataReader, and you start one more DataReader on the same connection.

---

What helped me was converting all the IQueryable types associated with the query that is throwing the error to more native types before using them in another query.