How do you reference a control inside a datalist template?

[DJVisuaL]

Hopefully this is an easy one!

I have a datalist bound to the table "items" which just lists the items.

In the footer template of the datalist I have "New Item" then a textbox and then an "add" button.

I simply want to take the text from the textbox and insert it into the table "items" thus adding a new item.

With the textbox outside on the page (not in the footer template of the datalist) this works fine but when I moved the textbox within the datalist footer it cannot find the control and I have no idea how to set the parameters for the insert because when you go to the datasource insert properties and try to get the value from a control it only lists the datalist's selected value and not any controls that are within the datalist (like my textbox in the footer)

I see in the source where the insert parameters are like this:

<InsertParameters>
   <asp:ControlParameter Name="ItemName" ControlID="TextBox1" PropertyName="Text" />
</InsertParameters>

I also see in visual studio when I select the textbox it is no longer just TextBox1 it is DataList1.HeaderandFooterTemplates.FooterTemplate.TextBox1
But if i set the ControlID to this it gives an error like:
Exception Details: System.InvalidOperationException: Could not find control 'DataList1.HeaderandFooterTemplates.FooterTemplate.TextBox1' in ControlParameter 'ItemName'.

I know there has to be a way but I am stumped. Any help is appreciated!

 

[jbenson001]

In the RowDataBound event of the datalist, check if you are accessing the footer. If you are, then get a reference to the button using .findcontrol().

 

[DJVisuaL]

I am not accessing the footer anywhere yet.
I am trying to set the insert paramter "@ItemName" to TextBox1.Text which is in the datalist's footer template

I tryed this in my page load but also doesn't work:

    protected void Page_Load(object sender, EventArgs e)
    {
        SqlDataSource1.InsertParameters.Add("@ListName", DataList1.FindControl("TextBox1").ID);
    }

I get this error:
Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

also tried the previous with .ClientID instead

 

[jbenson001]

Is the datalist bound at that point? If not, the textbox won't exist and you will get the NULL reference error.

 

[DJVisuaL]

The DataList is bound but the textbox at the bottom is not bound to anything. Maybe this is my problem? Basically it looks like this:

ITEMS
-----
apples
bananas
oranges
etc..
-----
Add new item <textbox here> <add button here>

table name is Items and there are only 2 fields ItemID and ItemName

I want to set a parameter where ItemName = @ItemName to TextBox1.Text so when I push the add button I can do SqlDataSource1.Insert();

hope this helps clarify

 

[jbenson001]

You will have to get a reference to the textbox in the ItemDataBound event of the DataList as I said before. You are trying to do it in the PageLoad which will cause the error you are getting.

    Protected Sub DataList1_ItemDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.DataListItemEventArgs) Handles DataList1.ItemDataBound
        If e.Item.ItemType = ListItemType.Footer Then
            'Find your textbox
            Dim tb As New TextBox
            tb = e.Item.FindControl("TextBox1")
            'Do other stuff here for your SqlDataSource
        End If
    End Sub

 

[DJVisuaL]

OK grand!
I understand this part now, thanks.

Now I have an insert query tied to SqlDataSource1 as such:

INSERT INTO Items(ItemName) VALUES (@ItemName)

so after 'Do other stuff here for your SqlDataSource I have

SqlDataSource1.InsertParameters.Add("ItemName", tb.Text);

I run the page and type something in TextBox1 and hit the Add button (Button1) and it gives me this error:

Cannot insert the value NULL into column 'ItemName', table '<table name.mdf>'; column does not allow nulls. INSERT fails.
The statement has been terminated.

The field doesn't allow NULLS but it shouldn't be null because I typed something in!

 

[jbenson001]

I don't use the datasoure objects for DB actions, so I may not be able to help much there. What is the code you are using to call the INsert?

 

[DJVisuaL]

OK thanks for your help so far. I think I am finally learning how things are done but I still have much to learn.

I haven't written any code to do the insert I have only set the Insert Query property of the DataList to

INSERT INTO Items(ItemName) VALUES (@ItemName)

so as I understand when SqlDataSource1.Insert() is called it will do the insert for you ASSUMING you have @ItemName set to something. So this part is working. It is trying to INSERT but my way of setting the @ItemName parameter is flawed in some way.

I'm going to search some more. At least this is a different problem and I'm making some progress.

 

[DJVisuaL]

Please take a look at this once again...
Now I am back to my original question.

I know how to set the parameters and have tested this and it works.

In my button code I can insert a static value into my table like this:

protected void Button1_Click(object sender, EventArgs e)
{
    SqlDataSource1.InsertParameters["ItemName"].DefaultValue = "new item test";
    SqlDataSource1.Insert();                
}

OK so my question is how do I get the text from the textbox and put it where "new item test" is? The textbox (TextBox1) and Button1 are both inside the datalist footer template.

I tryed this:

protected void Button1_Click(object sender, EventArgs e)
{
    TextBox tb = new TextBox();
    tb = (TextBox)Datalist1.FindControl("TextBox1");
    SqlDataSource1.InsertParameters["ItemName"].DefaultValue = tb.Text;
    SqlDataSource1.Insert();                
}

and got this error on line 26:

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error: 


Line 24:         TextBox tb = new TextBox();
Line 25:         tb = (TextBox)DataList1.FindControl("TextBox1");
Line 26:         SqlDataSource1.InsertParameters["ItemName"].DefaultValue = tb.Text;
Line 27:         SqlDataSource1.Insert();                
Line 28:     }

I know you said before that I have to get a reference from within the footer template itself in the ItemBound method. How do I make that reference accessible by the button1_click method?
If I try this:

protected void DataList1_ItemDataBound(object sender, DataListItemEventArgs e)
{
    if (e.Item.ItemType == ListItemType.Footer)
    {
        //Find insert textbox
        TextBox tb = new TextBox();
        tb = (TextBox)e.Item.FindControl("TextBox1");
    }
}
protected void Button1_Click(object sender, EventArgs e)
{
        SqlDataSource1.InsertParameters["ItemName"].DefaultValue = tb.Text;
		  SqlDataSource1.Insert();
}

I get this error:

CS0103: The name 'tb' does not exist in the current context

Sorry for my noobness.. I know there has to be a way to do this. You would think since the controls are in the same place that one could access the other easily but I guess not in ASP.NET.