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how to access listview value on delete command

Posted on 2014-01-29
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496 Views
Last Modified: 2014-01-30
I would like to ask for help regarding an asp page with a list view.

I want to get the Id value for the selected row, so that I can query the entity framework, get the record and delete it.

Down below is the code for when I do the e.Command = "Delete"
        If e.CommandName = "Delete" Then

            Dim myContext As New OLTPEntities
            Dim myRecipeStepsHistory = myContext.RefineRecipeStep.Where("it.Recipe_Id=" & Me.lvRecipeSteps.FindControl("Recipe_Id").ToString())
            Dim strRefineRecipeStepRecord = New StringBuilder("")

            If Not IsNothing(myRecipeStepsHistory) Then
                ' Recipe_Id
                strRefineRecipeStepRecord.Append("Recipe_Id: " & Me.lvRecipeSteps.FindControl("Recipe_Id").ToString() & ", ")

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I get an Object reference not set to an instance of an object, message.

Dim myRecipeStepsHistory = myContext.RefineRecipeStep.Where("it.Recipe_Id=" & Me.lvRecipeSteps.FindControl("Recipe_Id").ToString())  << this line, I thinkis because I am not looking for the right control?

I have attached a copy of my aspx code. Hopefully some one will be able to provide guidance on this problem.

Thank you much.
listview-aspx-code.txt
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Comment
Question by:metropia
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6 Comments
 
LVL 52

Expert Comment

by:Carl Tawn
ID: 39818149
What event are you using to do the delete? The ListView Deleting event passes a Keys collection as part of it EventArgs. That collection will include the ID of the row being deleted.
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Author Comment

by:metropia
ID: 39818189
I started using:
Private Sub lvRecipeSteps_ItemCommand(sender As Object, e As ListViewCommandEventArgs) Handles lvRecipeSteps.ItemCommand

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And then check the Command Name:
If e.CommandName = "Delete"

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I now changed the code to use ItemDeleting event, because I have a DataKeyNames="Id"
defined, but I have not been able to figure out how to access it and then query the Entities.
Private Sub lvRecipeSteps_ItemDeleting(sender As Object, e As ListViewDeleteEventArgs) Handles lvRecipeSteps.ItemDeleting
Dim myContext As New OLTPEntities
Dim myRefineRecipeSteps = myContext.RefineRecipeStep.Where("it.Id=" & Me.lvRecipeSteps.DataKeys().ToString())   << this does not work

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0
 

Author Comment

by:metropia
ID: 39818277
I am still not able to make it work. I hope you can offer some help.

I really need it.

Thank you
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Author Comment

by:metropia
ID: 39818301
This is my current code and my error.

screen shot error - current
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LVL 52

Assisted Solution

by:Carl Tawn
Carl Tawn earned 250 total points
ID: 39820297
You don't need to cast the data key to a textbox. Try:
Dim myRefineRecipeSteps = myContext.RefineRecipeStep.Where("it.Id=" & currentDataKey.Value).FirstOrDefault()

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LVL 83

Accepted Solution

by:
CodeCruiser earned 250 total points
ID: 39820508
Try changing

Dim myRefineRecipeSteps = myContext.RefineRecipeStep.Where("it.Id=" & Me.lvRecipeSteps.DataKeys().ToString())


to

Dim myRefineRecipeSteps = myContext.RefineRecipeStep.Where("it.Id=" & e.Keys("ID"))
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