textboxes are empty on postback with bootstrap modal asp.net

Question

I am using bootstrap modal in my asp.net page like this:

Answer 1

Steven Anderson is right, values are not posted because modal inputs are outside the form.

I was able to workaround this problem using javascript to copy the value of the modal inputs to hidden asp.net controls.

I create a hidden asp.net control outside of the modal:

The modal textbox I want to submit:

`

My modal submit button looks like this;

My JavaScript function looks like:

function DoCustomPost()
{
var ModalTextBox = document.getElementById("FormAmenity");
var HiddenTextBox = document.getElementById("MyHiddenControl");
// This is the value I want to Post
MyHiddenControl.value = ModalTextBox.value
}

So when I click "submit" in my modal window a postback kicks, the value of the textbox is copied to the hidden control and I can read the value from the hidden control in code-behind:

Protected Sub BtnSubmit_Click(sender As Object, e As EventArgs) Handles BtnSubmit.Click
Dim Something As String = MyHiddenControl.Value
End Sub