如何在不覆盖第一行值的情况下将值添加到临时gridview？ [英] How to add values to a temporary gridview without overwriting the first row values?

问题描述

Goodday！

我想在保存之前创建临时gridview。当我在文本框中输入值时，单击Add，然后它将填充gridview。



问题：

1.当我成功添加第一行的值并添加新值时。它会覆盖第一行值。我想在下一行创建新值。或者只是创建一个新行，然后显示从文本框输入的新值。





这是我的代码：

Goodday!
I wanted to create a temporary gridview before saving.When I enter values on textboxs , click Add, then it will populate the gridview.

The problem:
1. When I have successfully added values for the first row, and add new values. It overwrites the first row values. I wanted to make the new values on the next row. Or just create a new row then show the new values that has been inputted from the textboxes.


Here is my code:

Dim dt As New DataTable()

       dt.Columns.AddRange(New DataColumn(6) {New DataColumn("Code"), New DataColumn("Description"), New DataColumn("Specification"), New DataColumn("Availability"), New DataColumn("Storage Location"), New DataColumn("Quantity"), New DataColumn("Critical")})
       dt.Rows.Add(componentCodeTextbox.Text, DescriptionTextbox.Text, txt_specs.Text, cb_availability.SelectedItem, txt_location.Text, QuantityTextbox.Text, CriticalTextbox.Text)

       ViewState("dt") = dt
       TempGV.DataSource = TryCast(ViewState("dt"), DataTable)
       TempGV.DataBind()

结束次级





但有错误：

Dim dr As datarow = dt.NewRow（）





错误：对象null引用异常

我是否必须添加其他代码才能添加新行？



任何帮助将不胜感激。在此先感谢。

End Sub


But has error in :
Dim dr As datarow = dt.NewRow()


ERROR: object null reference exception
do I have to add other code so that I could add new row?

Any help would be much appreciated. Thanks in advance.

推荐答案

这是我的参考，它解决了我的问题。

This is my reference, and it solved my problem.

Protected Sub BtnAddCourses_Click(sender As Object, e As EventArgs)
	Dim dt As datatable = New DataTable()
	If ViewState("ANYSTRING") Is Nothing Then
		dt.Columns.Add("COLUMNNAME1")
		dt.Columns.Add("COLUMNNAME2")
		dt.Columns.Add("COLUMNNAME3")
	Else
		dt = DirectCast(ViewState("ANYSTRING"), DataTable)
	End If
	Dim dr As datarow = dt.NewRow()
	dr("COLUMNNAME1") = TEXTBOX1.TEXT
	dr("COLUMNNAME2") = DROPDOWNLIST.SELECTEDVALUE
	dr("COLUMNNAME3") = TEXTBOX1.TEXT
	dt.Rows.Add(dr)
	ViewState("ANYSTRING") = dt
	GRIDVIEW.DataSource = dt
	GRIDVIEW.DataBind()
	GRIDVIEW.Visible = True
End Sub

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