composite control renders after i need to use one of the properties (control lifecycle)

Question

I have created a composite control for a file upload input (using an HtmlInputFile control). My problema is that everything works fine until I try to save the file using HtmlInputFile's "SaveAs" in my page's code behind. Whenever I press the button for uploading the file, I get a "object not set to an instance bla bla bla". However if I pause execution right before the SaveAs (with a break point) and then got step by step (F10), all of the composite properties have the corresponding data and I can effectively upload the file.

I am quite sure this has to do with page and control lifecycle, but everything I have read so far has led me no where. Can anyone please shed some light as to how I can force the composite control to load/render before I execute the code behind Click event?

The code behind that triggers the SaveAs is pretty straight forward:

Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
    fup.xmsPostedFile.SaveAs(Server.MapPath(String.Format("~/memberpages/{0}", fup.xmsFileName)))
End Sub

The fup.xmsPostedFile property only references the _inputControl.PostedFile property. Same with fup.xmsFileName.

any help will be greatly appreciated. Thanks in advanced.

score 0 · Answer 1 · answered Oct 24 '14 at 12:12

Finally got it to work. Turns out I was missing the EnsureChildControls(). I changed the property for this:

    Public ReadOnly Property xmsPostedFile() As HttpPostedFile
        Get
            Return _inputFile.PostedFile
        End Get
    End Property

to this

    Public ReadOnly Property xmsPostedFile() As HttpPostedFile
        Get
            EnsureChildControls()
            Return _inputFile.PostedFile
        End Get
    End Property

and it started working as expected.

composite control renders after i need to use one of the properties (control lifecycle)

1 Answers1