Making a Control Accept Generics

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C#

ASP.NET

generics

Hi All,

I’m trying to create a control for a process I use all the time. Basically, I can have a list of available objects and a list of currently used objects. I then move objects from list to list, very simple. I use this process a lot with varying types of objects. I’m now tired of duplicating my work and have decided to create a control I can just use at will. I figure because I use this with varying object type it should use generic lists to populate the listboxes on the control. But, this is where I’m having difficulties. I want to set this control on any giving page and pass in various object lists and have it work. Below is some code but I cannot figure out how to make the control accept an unknown object list.

I have not even gotten to returning the new current object list. Any help would be greatly appreciated. Thanks.

Eric

This is how I would like to place the control on some page. I’d supply value to a control like this:

<xxx:AvailCurLists ID="ACM1" runat="server" Name="Etester"
                             DataText="PropertyName"
                             DataValue="PropertyID"
                             CurrentAssignments='<%#CurrentAssignments() %>'
                             AvailableAssignments='<%#AvailableAssignments() %>' />

On the control side thing look like this:

<div class="label"><%#Eval("Name")%></div>
<br />
<table>
    <tr align="center">
        <td>
            <asp:Label ID="lblAvailable" runat="server" CssClass="programsLabel" Text="Available Malls"></asp:Label>
        </td>
        <td></td>
        <td></td>
        <td></td>
        <td>
            <asp:Label ID="lblCurrent" runat="server" CssClass="programsLabel" Text="Current Malls"></asp:Label>
        </td>
    </tr>
    <tr align="center">
        <td>
            <asp:ListBox ID="lbAvailable" runat="server"
                                CssClass="items" SelectionMode="Multiple"
                                Height="200px" DataTextField='<%#DataText %>'
                                DataValueField='<%#DataValue %>' DataSource='<%#AvailableAssignments %>'>
            </asp:ListBox>
        </td>
        <td></td>
        <td></td>
        <td>
            <asp:Button ID="btnAdd" runat="server" Text="Add Value -->" OnClick="btnAdd_Click" />
            <br />
            <br />
            <asp:Button ID="btnRemove" runat="server" Text="<-- Remove Value" OnClick="btnRemove_Click" />
        </td>
        <td>
            <asp:ListBox ID="lbCurrent" runat="server"
                                CssClass="items" SelectionMode="Multiple"
                                Height="200px" DataTextField='<%#DataText %>'
                                DataValueField='<%#DataValue %>' DataSource='<%#CurrentAssignments %>'>
            </asp:ListBox>
        </td>
    </tr>
</table>

Code Behind so far:

public partial class AvailableCurrent : System.Web.UI.UserControl
{
    private string _name = null;
    public string Name
    {
        get
        {
            return _name;
        }
        set
        {
            _name = value;
        }
    }

    private string _dataText = null;
    public string DataText
    {
        get
        {
            return _dataText;
        }
        set
        {
            _dataText = value;
        }
    }

    private string _dataValue = null;
    public string DataValue
    {
        get
        {
            return _dataValue;
        }
        set
        {
            _dataValue = value;
        }
    }

    private List<T> _AvailableAssignments = null;
    public List<T> AvailableAssignments
    {
        get
        {
            return _AvailableAssignments;
        }
        set
        {
            _AvailableAssignments = value;
        }
    }

    private List<T> _CurrentAssignments = null;
    public List<T> CurrentAssignments
    {
        get
        {
            return _CurrentAssignments;
        }
        set
        {
            _CurrentAssignments = value;
        }
    }

    protected void btnAdd_Click(object sender, EventArgs e)
    {
        if (lbAvailable.SelectedItem != null)
        {
            var items = (from ListItem li in lbAvailable.Items
                         where li.Selected == true
                         select li).ToList();

            foreach (ListItem li in items)
            {
                lbCurrent.Items.Add(new ListItem(li.Text, li.Value));
                lbAvailable.Items.Remove(li);
            }
        }
    }

    protected void btnRemove_Click(object sender, EventArgs e)
    {
        if (lbCurrent.SelectedItem != null)
        {
            //multi-move...
            var mItems = (from ListItem li in lbCurrent.Items
                          where li.Selected == true
                          select li).ToList();

            foreach (ListItem li in mItems)
            {
                lbAvailable.Items.Add(new ListItem(li.Text, li.Value));
                lbCurrent.Items.Remove(li);
            }

            //sorting...
            var items = (from ListItem li in lbAvailable.Items
                         orderby li.Text
                         select li).ToList();

            lbAvailable.Items.Clear();

            foreach (ListItem li in items)
                lbAvailable.Items.Add(new ListItem(li.Text, li.Value));
        }
    }

}

[edit]Code block added - OriginalGriff[/edit]