CODEWITHSUNDEEP
c#asp.net.netgridview
power2havenots
power2havenots

Reputation: 62

In a .net gridview can a template field populate a drop-downlist

I have data returning to a Gridview in .net from a dynamic database and one of the fields has a long list of semi-colon delimited values. I was able to display this data using line breaks in place of semi-colons however as there is potentially up to 20 values in this field I'm sure there's a better way of displaying this.

I used the following code to create and amend a template field:

<asp:TemplateField HeaderText="Amalgamation"
                    SortExpression="Amalgamation">
                    <ItemTemplate>
                        <%# Eval("Amalgamation").ToString().Replace(";", "<br />")%>
                    </ItemTemplate>
                </asp:TemplateField>

An example of the data which will populate this field is: 100001;100002;600001;600006.

Update: Ive tried this but had no joy. In the html:

<%#PopulateArray((string)(Eval("Amalgamation")))%> <asp:DropDownList ID="ddlStrings" AutoPostBack="true" runat="server"></asp:DropDownList>

Then this function in the code behind: 

public object PopulateArray(string s) 
{ 
string[] sArray = s.Split(';'); 
DropDownList ddl = new DropDownList(); 
ddl = (DropDownList)this.Page.FindControl("ddlStrings"); 
ddl.DataSource = sArray; 
ddl.DataBind();
return sArray;
}

I get a NullReferenceException on the line: ddl.DataSource = sArray

Upvotes: 0

Views: 918

Answers (4)

power2havenots
power2havenots

Reputation: 62

OK I've got the bottom of it. I was referencing the ID for the Dropdown instead of referencing each row instance of it. I put the code in the row created event of the gridview using the parameter:

onrowcreated="ArrayDataView_RowCreated"

I split the result using the semi-colon delimiter every time a row was created in the table. I also cast each result using the object class ("MyData") I was using for the database. I then had to filter out the header and footer data rows of the gridview using an "if" statement. Here is the row created code in the code behind:

    protected void ArrayDataView_RowCreated(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            DropDownList ddl = (DropDownList)e.Row.FindControl("ddlStrings");
            ddl.DataSource = (e.Row.DataItem as MyData).Amalgamation.Split(';');
        }       
    }
}

I dropped the eval function in the aspx page and the item template in the gridview was just reduced to housing the drop down:

<ItemTemplate>
<asp:DropDownList ID="ddlStrings" AutoPostBack="false" runat="server"></asp:DropDownList></ItemTemplate>

Thanks to all who helped!

Upvotes: 0

Steve
Steve

Reputation: 549

I think you could do that, but you wouldn't have to bind to a dropdown if it is just for display. You could just add the markup to make a standard html dropdown list.

If you want to get fancy, how about a function that returns some html with a which shows the first few items, a "..." if there are more, and some script to expand it to show the whole list when you mouseover the , or something like that?

Upvotes: 0

Ann L.
Ann L.

Reputation: 13965

I am assuming that you only want to display this data. If you want the user to be able to edit the data but to be able to reassemble it into a delimited string, that's a much more complex problem -- so much so that you might want to reconsider how you are storing the data in the database.

The easiest way to turn a delimited string into an array of strings is to use the String.Split method:

string s = "111;333;555;";
string[] sParts = s.Split(";");

You might have to do this in code-behind, though, rather than in a binding expression, because you not only need to split the string, you probably want to bind it to something. There are a number of options: you might like the BulletedList web control.

Upvotes: 1

Manoj Purohit
Manoj Purohit

Reputation: 3453

Binding to a dropdown seems to be a good idea...if at all you need to edit this in <EditItemTemplate> , for displaying purpose this is good enough...

Upvotes: 0

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