Tag: EF

View Generated SQL in Entity Framework (EF)

Hey everyone,

Just a quick post on how to view the generated sql in entity framework. To start with, just add the following line to your db context constructor:

public class TestDbContext : DbContext
    {
        public TestDbContext() : base("name=TestDbContext")
        {
            this.Database.Log = s => System.Diagnostics.Debug.WriteLine(s); //This line
        }
        ...

With this line added, you should now be able to see all of your generated sql in the output window.

SELECT TOP (1) 
    [Project1].[VidId] AS [VidId], 
    [Project1].[CreatedAt] AS [CreatedAt], 
    [Project1].[Check] AS [Check], 
    [Project1].[SourceCheck] AS [SourceCheck]
    FROM ( SELECT 
        [Extent1].[VidId] AS [VidId], 
        [Extent1].[CreatedAt] AS [CreatedAt], 
        [Extent1].[Check] AS [Check], 
        [Extent1].[SourceCheck] AS [SourceCheck]
        FROM [dbo].[Vids] AS [Extent1]
        WHERE [Extent1].[VidId] < @p__linq__0
    )  AS [Project1]
    ORDER BY [Project1].[VidId] DESC

-- p__linq__0: '535' (Type = Int32)
-- Executing at 28/06/2014 5:00:16 PM +10:00
-- Completed in 0 ms with result: SqlDataReader

If you’re not using EF6, there were a few other options where I came across this solution: http://stackoverflow.com/a/20751723/522859

Duplicate type name within an assembly. – Entity FrameWork (EF)

Hey everyone,

I ran into this error message while trying to debug a project today:

“Duplicate type name within an assembly.”

 

The workaround to this was actually pretty weird. Remove all of your breakpoints that appear before this exception and place one after it instead. That’s it!

A bit of a weird issue, but according to the StackOverflow post where I found the solution Microsoft are aware of it: http://stackoverflow.com/a/23529882/522859

There is already an open DataReader associated with this Command which must be closed first. – ASP.NET MVC

Hey everyone,

I ran into the following error this morning:

There is already an open DataReader associated with this Command which must be closed first.

It turns out there are a few causes for this. My issue was that I was attempting to open a result set while already iterating over another one. 


 //Retrieve list of cart products and create list of suborders
 var cartProducts = db.CartProducts.Where(cartProduct => cartProduct.CartId == userOrder.CartId);

//Loop through each cart product
foreach(var cartProduct in cartProducts)
{
     //Retrieve suborder
     SubOrder subOrder = subOrders.Find(x => x.BusinessId == cartProduct.Product.BusinessId);

The solution to this was pretty easy thankfully. Simply add “ToList()” to the end of the initial request:


 //Retrieve list of cart products and create list of suborders
 var cartProducts = db.CartProducts.Where(cartProduct => cartProduct.CartId == userOrder.CartId).ToList();

An alternative solution is to modify your connection string in order to allow multiple result multiple result sets. Simply add the following to provider part:

MultipleActiveResultSets=true

Checkout these StackOverflow posts for more info:
http://stackoverflow.com/a/10498776/522859
http://stackoverflow.com/a/6064422/522859