Fire DropDownList event in a repeater *RESOLVED*

[dj4uk]

I have two dropdownlists within a repeater (simplified code below):

<asp:Repeater id="rptProducts" Runat="Server">
	<ItemTemplate>
		<asp:DropDownList id="ddlColour" Runat="Server" DataSource="<%# BindColour((int)DataBinder.Eval(Container.DataItem, "ProductID")) %>" DataTextField="ColourName" DataValueField="ColourID" />
		<asp:DropDownList id="ddlSize" Runat="Server" DataSource="<%# BindSize((int)DataBinder.Eval(Container.DataItem, "ProductID")) %>" DataTextField="SizeName" DataValueField="SizeID" />
	</ItemTemplate>
</asp:Repeater>

The repeater is bound to a list of products. The BindColour and BindSize methods return lists according to the productID for that Item.

My query is how can I detect that the first dropdownlist (colour) has changed value and therefore databind the second dropdownlist again to reflect the selected value.

Basically the first list contains all colours for a particular product and the second dropdown displays sizes for a product AND colour.

Help would be appreciated.

DJ

[dj4uk]

Sorted it!

I do the first databind within the repeater event ItemDataBound.

When one of the first dropdownlists within the repeater itemtemplate changes its selected index it fires the dropdownlists SelectedIndexChanged event. The difficulty I had was accessing the other dropdownlist within the repeater item so I can databind it according to the new selected index of the first dropdownlist.

In the end I used the Parent property of the sender argument to access the repeater item and then used the FindControls method to grab the second dropdownlist.

    void rptRelatedProducts_ItemDataBound(Object sender, RepeaterItemEventArgs e) {
        Label productID;
        DropDownList colourList;
        DropDownList sizeList;
        int colourID;

        // Switch to work out which item is being data bound
        switch (e.Item.ItemType) {
            case ListItemType.Item:
            case ListItemType.AlternatingItem:
                // If its an Item then databind the two dropdownlists
                // lblProductID is a hidden label holding the productID
                productID = (Label) e.Item.FindControl("lblProductID");
                colourList = (DropDownList) e.Item.FindControl("ddlColour");
                sizeList = (DropDownList) e.Item.FindControl("ddlSize");

                // DataBind the colour list
                colourList.DataSource = AvailableColours(Convert.ToInt32(productID.Text));
                colourList.DataBind();

                // Grab the current selected colourID if one isn't selected grab
                // the first on the list
                if (colourList.SelectedValue == String.Empty) {
                    if (colourList.Items.Count > 0) {
                        colourList.SelectedIndex = 0;
                        colourID = Convert.ToInt32(colourList.SelectedValue);
                    } else {
                        colourID = 0;
                    }
                } else {
                    colourID = Convert.ToInt32(colourList.SelectedValue);
                }

                // DataBind the size list
                sizeList.DataSource = AvailableSizes(Convert.ToInt32(productID.Text), colourID);
                sizeList.DataBind();

                // Select the first on the list
                if (sizeList.SelectedValue == String.Empty) {
                    if (sizeList.Items.Count > 0) {
                        sizeList.SelectedIndex = 0;
                    }
                }
            break;
            case ListItemType.Header:
            break;
            case ListItemType.Footer:
            break;
            case ListItemType.Separator:
            break;
        }
    }

    void ddlColour_SelectedIndexChanged(Object sender, EventArgs e) {
        Label productID;
        DropDownList colourList;
        DropDownList sizeList;
        int sizeID;

        // Load the controls needs
        colourList = (DropDownList) sender;
        productID = (Label) colourList.Parent.FindControl("lblProductID");
        sizeList = (DropDownList) colourList.Parent.FindControl("ddlSize");

        // Grab any already selected size value
        if (sizeList.SelectedValue == String.Empty) {
            if (sizeList.Items.Count > 0) {
                sizeID = Convert.ToInt32(sizeList.Items[0].Value);
            } else {
                sizeID = 0;
            }
        } else {
            sizeID = Convert.ToInt32(sizeList.SelectedValue);
        }

        // Rebind the size list according to the new colour ID selected
        sizeList.DataSource = AvailableSizes(Convert.ToInt32(productID.Text), Convert.ToInt32(colourList.SelectedValue));
        sizeList.DataBind();

        // Reselect the previous selected size ID or if there wasn't one
        // select the first on the list.
        if (sizeList.Items.FindByValue(sizeID.ToString()) != null) {
            sizeList.SelectedValue = sizeID.ToString();
        } else {
            if (sizeList.Items.Count > 0) {
                sizeList.SelectedIndex = 0;
            }
        }
    }

Phew!

DJ