EntiryFramwork CodeFirst with GridView

Question

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Hi,

I am new to entity framework and found that the CodeFirst release is okay. So I decided to create a simple asp.net webforms application to test this. Populated a table with some data and tried to retrieve the data with the following code:

VB

Imports System.Data.Entity

Public Class AdmonHRMDbContext
    Inherits DbContext

    Public Property Application_User As DbSet(Of User)
End Class

VB

Public Class User
    Public Property UserId As Int32
    Public Property LoginName As String
    Public Property Password As String
End Class

Public Class UserRepository

    Private context As AdmonHRMDbContext

    Public Sub New()
        context = New AdmonHRMDbContext
    End Sub

    Public Function GetUsers() As IQueryable(Of User)
        Return context.Application_User
    End Function
End Class

VB

Protected Sub Button1_Click(sender As Object, e As System.EventArgs) Handles Button1.Click
    Dim u As New BusinessLogic.UserRepository()

    GridView1.DataSource = u.GetUsers
    GridView1.DataBind()
End Sub

below is the exception I got:
Data binding directly to a store query (DbSet, DbQuery, DbSqlQuery) is not supported. Instead populate a DbSet with data, for example by calling Load on the DbSet, and then bind to local data. For WPF bind to DbSet.Local. For WinForms bind to DbSet.Local.ToBindingList().

I don't know what to do please help

Aweklin

Posted 23-Sep-11 2:54am

awedaonline

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2 solutions

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Simon Bang Terkildsen · Accepted Answer · 2011-09-23T03:14:00

Solution 1

you can't bind to IQueryable as it only desribes how and what data to retrieve. You'll have to actually query the data first, e.g. by using the ToList extension method.

C#

GridView1.DataSource = u.GetUsers.ToList()

Posted 23-Sep-11 3:14am

Simon Bang Terkildsen

Comments

RaisKazi 23-Sep-11 9:17am

Agree. 5!

Yuri Vital 23-Sep-11 9:24am

Me too. 5 !

Simon Bang Terkildsen 23-Sep-11 9:35am

Thanks to both of you.

Simon Bang Terkildsen 23-Sep-11 9:31am

OP Wrote
Thanks Simon,

GridView1.DataSource = u.GetUsers.ToList

I have tried that but got this error:

EntityCommandExecutionException was unhandled by user code:
An error occurred while executing the command definition. See the inner exception for details.

Simon Bang Terkildsen 23-Sep-11 9:33am

Hmm I don't know why it would throw an exception, can you post the inner exception, please.

sasolanki007 · Accepted Answer · 2011-09-23T03:30:00

Solution 3

Try following code :

VB

Public Function GetUsers() As List(Of User)
     Return context.Application_User.ToList()
End Function

-Sagar Solanki

Posted 23-Sep-11 3:30am

sasolanki007

Comments

Simon Bang Terkildsen 23-Sep-11 9:35am

I already suggested that he should use the ToList extension method, but for some reason it throws an exception, see the comments to solution 1.