c＃网格视图中的下拉列表

Question

I am a grid view that I have that I can edit, update, delete from. I can manually add a drop down and have the selected value populate correctly, but I want to be able to populate the drop down from the database (and show the selected value correctly) when editing it.

I have tried a bunch of searches/options but can not find a way to make it work.

My code is below:

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            PopulateData();
            lblMessage.Text = "";
        }

        string sSQL = "";

        // populate drop downs
        sSQL = @"SELECT ErrorTypeLookupID as Value, ErrorDescription as DisplayText
            FROM BabelFish.dbo.ErrorTypeLookup (NOLOCK)
            WHERE ErrorType = 'Category'
            ";
        //ORDER BY OrderBy, ErrorDescription";

        new DatabaseConnection().PopulateListBoxFromDB(sSQL, "", lstNewResolutionCategory);


        sSQL = @"SELECT ErrorTypeLookupID as Value, ErrorDescription as DisplayText
            FROM BabelFish.dbo.ErrorTypeLookup (NOLOCK)
            WHERE ErrorType = 'Severity'
            ";
        //ORDER BY OrderBy, ErrorDescription";

        new DatabaseConnection().PopulateListBoxFromDB(sSQL, "", lstNewResolutionSeverity);


    }//end page load


    protected void DeleteRow(object sender, GridViewDeleteEventArgs e)
    {

        var ResolutionsID = GridView1.DataKeys[e.RowIndex].Value;

        GridViewRow row = GridView1.Rows[e.RowIndex] as GridViewRow;

        string sSQL = "Delete from BabelFish.dbo.Resolutions where ResolutionsID = @ResolutionsID";

        SqlCommand sCommand = new SqlCommand(sSQL);

        sCommand.Parameters.AddWithValue("@ResolutionsID", ResolutionsID);

        // run delete
        new DatabaseConnection().RSExecute(sCommand);

        lblMessage.Text = "Record deleted successfully !";

        GridView1.EditIndex = -1;

        this.PopulateData();

    }




    protected void UpdateRow(object sender, GridViewUpdateEventArgs e)
    {

        var ResolutionsID = GridView1.DataKeys[e.RowIndex].Value;

        GridViewRow row = GridView1.Rows[e.RowIndex] as GridViewRow;

        TextBox txtResolutionDescription = row.FindControl("txtResolutionDescription") as TextBox;
        DropDownList drpErrorCategoryID = row.FindControl("ErrorCategory") as DropDownList;


        string sSQL = @"Update BabelFish.dbo.Resolutions set 
                    ResolutionDescription = @ResolutionDescription,
                    UserIDSolved = ISNULL(BabelFish.dbo.fn_GetUserIDFromTeamMemberTable(@UserIDSolved), BabelFish.dbo.fn_GetUserIDFromTeamMemberTable(REPLACE(@UserIDSolved, '-', ''))), 
                    DateTimeSolved = ISNULL(DateTimeSolved, GetDate())                        
                    where ResolutionsID = @ResolutionsID";

        SqlCommand sCommand = new SqlCommand(sSQL);

        sCommand.Parameters.AddWithValue("@ResolutionDescription", txtResolutionDescription.Text.Trim());
        sCommand.Parameters.AddWithValue("@ResolutionsID", ResolutionsID);
        sCommand.Parameters.AddWithValue("@UserIDSolved", UserID);

        // run update
        new DatabaseConnection().RSExecute(sCommand);


        lblMessage.Text = "Record updated successfully !";

        GridView1.EditIndex = -1;

        this.PopulateData();

    }




    private void PopulateData()
    {
        string sSQL = @"SELECT
                ResolutionsID, ErrorTableID, BabelFish.dbo.fn_GetUserNameFromTeamMemberTable(UserIDSolved) as UserIDSolved, 
                DateTimeSolved, ResolutionDescription, ResolutionCategory, ResolutionSeverity, IsActive
                FROM BabelFish.dbo.Resolutions (NOLOCK)
                Where ErrorTableID = '" + ErrorTableID + "'";

        DataTable dt = DatabaseAccessing.DatabaseConnection.GetDataTable(sSQL);

        // only do if more then 1 row exists
        if (dt.Rows.Count > 0)
        {
            GridView1.DataSource = dt;

            GridView1.DataBind();
        }
        else
        {
            lblMessage.Text = "No Rows Exist.";
        }




    }


    protected void AddRow(object sender, EventArgs e)
    {
        // get values to add to database
        string txtResolutionDescription = txtNewResolutionDescription.Text.ToString();

        string lstCategoryID = lstNewResolutionCategory.SelectedValue;
        string lstSeverityID = lstNewResolutionSeverity.SelectedValue;

        string sSQL = @"INSERT INTO BabelFish.dbo.Resolutions (
            ErrorTableID, UserIDSolved, DateTimeSolved, ResolutionDescription, 
            ResolutionCategory, ResolutionSeverity, IsActive
        )

        VALUES (
            @ErrorTableID, ISNULL(BabelFish.dbo.fn_GetUserIDFromTeamMemberTable(@UserIDSolved), BabelFish.dbo.fn_GetUserIDFromTeamMemberTable(REPLACE(@UserIDSolved, '-', ''))), 
            GetDate(), @ResolutionDescription,
            @ResolutionCategory, @ResolutionSeverity, 1
        )";


        SqlCommand sCommand = new SqlCommand(sSQL);

        sCommand.Parameters.AddWithValue("@ErrorTableID", ErrorTableID);
        sCommand.Parameters.AddWithValue("@UserIDSolved", UserID);
        sCommand.Parameters.AddWithValue("@ResolutionDescription", txtResolutionDescription);
        sCommand.Parameters.AddWithValue("@ResolutionCategory", lstCategoryID);
        sCommand.Parameters.AddWithValue("@ResolutionSeverity", lstSeverityID);


        // run update
        new DatabaseConnection().RSExecute(sCommand);


        lblMessage.Text = "Record successfully added!";

        GridView1.EditIndex = -1;

        this.PopulateData();
    }


    protected void EditRow(object sender, GridViewEditEventArgs e)
    {
        GridView1.EditIndex = e.NewEditIndex;

        this.PopulateData();

        /*
        //not working, ddl is NULL
        var ddl = (DropDownList)GridView1.FindControl("selResolutionSeverity");

        string sSQL = @"SELECT ErrorTypeLookupID as Value, ErrorDescription as DisplayText
            FROM BabelFish.dbo.ErrorTypeLookup (NOLOCK)
            WHERE ErrorType = 'Severity' ";


        DataSet DS = new DatabaseAccessing.DatabaseConnection().DS(sSQL);

        ddl.DataSource = DS;
        ddl.DataTextField = "DisplayText";
        ddl.DataValueField = "Value";
        ddl.DataBind();
        ddl.Items.Insert(0, new ListItem("-- Select --", "0"));
         * */
    }



    protected void CancelEditRow(object sender, GridViewCancelEditEventArgs e)
    {
        GridView1.EditIndex = -1;
        this.PopulateData();
    }


    protected void ChangePage(object sender, GridViewPageEventArgs e)
    {

        GridView1.PageIndex = e.NewPageIndex;
        this.PopulateData();

    }



    <asp:Label ID="lblMessage" runat="server" ForeColor="Green" EnableViewState="false" />

    <asp:GridView ID="GridView1" runat="server" CellPadding="4" ForeColor="#333333" GridLines="None"
        AutoGenerateColumns="false" 
        Width="100%" 
        OnRowEditing="EditRow" 
        OnRowCancelingEdit="CancelEditRow"
        OnRowUpdating="UpdateRow" 
        DataKeyNames="ResolutionsID" 
        OnRowDeleting="DeleteRow" 
        AllowPaging="true"
        PageSize="50" 
        OnPageIndexChanging="ChangePage"            

        >

    <Columns>

        <asp:TemplateField HeaderText="Edit">

            <ItemTemplate>
                <asp:LinkButton ID="lnkEdit" runat="server" Text="Edit" CommandName="Edit" />
            </ItemTemplate>

            <EditItemTemplate>

                <asp:LinkButton ID="lnkUpdate" runat="server" Text="Update" CommandName="Update" />

                <asp:LinkButton ID="lnkCancel" runat="server" Text="Cancel" CommandName="Cancel" />

            </EditItemTemplate>

        </asp:TemplateField>


        <asp:BoundField HeaderText="ResolutionsID" DataField="ResolutionsID" ReadOnly="true" />

        <asp:TemplateField HeaderText="ResolutionDescription">
            <ItemTemplate><%# Eval("ResolutionDescription")%></ItemTemplate>

            <EditItemTemplate>
                <asp:TextBox ID="txtResolutionDescription" runat="server" Text='<%# Eval("ResolutionDescription") %>'/>
            </EditItemTemplate>
        </asp:TemplateField>

        <asp:BoundField HeaderText="UserIDSolved" DataField="UserIDSolved" ReadOnly="true" />

        <asp:TemplateField HeaderText="Category">
            <ItemTemplate>
                <%# Eval("ResolutionCategory")%>
            </ItemTemplate>

            <HeaderStyle HorizontalAlign="Left" />
                <EditItemTemplate>  
                    <asp:DropDownList ID="selResolutionCategory" runat="server" SelectedValue='<%# Eval("ResolutionCategory") %>'>         
                        <asp:ListItem Text="-- Select One --" Value="0" />
                        <asp:ListItem Text="cat1" Value="1" />
                        <asp:ListItem Text="cat2" Value="2" />        
                    </asp:DropDownList>
                </EditItemTemplate>
        </asp:TemplateField>


        <asp:TemplateField HeaderText="Severity">
            <ItemTemplate>
                <%# Eval("ResolutionSeverity")%>
            </ItemTemplate>

            <HeaderStyle HorizontalAlign="Left" />
                <EditItemTemplate>  
                    <asp:DropDownList ID="selResolutionSeverity" runat="server">                                     
                    </asp:DropDownList>
                </EditItemTemplate>
        </asp:TemplateField>


        <asp:TemplateField HeaderText="Delete?">
            <ItemTemplate>
                <span onclick="return confirm('Are you sure to delete?')">
                    <asp:LinkButton ID="lnkDelete" runat="server" Text="Delete" ForeColor="Red" CommandName="Delete" />
                </span>
            </ItemTemplate>

        </asp:TemplateField> 


    </Columns>

    <AlternatingRowStyle BackColor="White" />

    <EditRowStyle BackColor="#efefef" />

    <FooterStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />

    <HeaderStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />

    <PagerStyle BackColor="#2461BF" ForeColor="White" HorizontalAlign="Center" />

    <RowStyle BackColor="#EFF3FB" />

    <SelectedRowStyle BackColor="#D1DDF1" Font-Bold="True" ForeColor="#333333" />

    <SortedAscendingCellStyle BackColor="#F5F7FB" />

    <SortedAscendingHeaderStyle BackColor="#6D95E1" />

    <SortedDescendingCellStyle BackColor="#E9EBEF" />

    <SortedDescendingHeaderStyle BackColor="#4870BE" />

    </asp:GridView>

Answer 1

You are going to want to use OnRowDataBound. Here is the example of how I populate one of my drop downs within my gridview.

protected void gvVehicle_OnRowDataBound(object sender, GridViewRowEventArgs e)
    {
        foreach (GridViewRow gvr in gvVehicleTEMP.Rows)
        {
            DropDownList ddlLocation = ((DropDownList)gvr.FindControl("ddlLocation"));
            Label lblLocationLabel = ((Label)gvr.FindControl("lblLocationLabel"));

            conn.Close();
            conn.Open();

            SqlCommand cmdLocationNames = new SqlCommand("SELECT Name FROM Billers WHERE Store = '" + 1 + "' ORDER BY Name ASC", conn);
            List<string> internalLocationsList = new List<string>();

            using (SqlDataReader reader = cmdLocationNames.ExecuteReader())
            {
                while (reader.Read())
                {
                    string interlocations = reader.GetString(0);
                    internalLocationsList.Add(interlocations);
                }
                foreach (string locname in internalLocationsList)
                {
                    ddlLocation.Items.Add(new ListItem(locname));
                    conn.Close();
                }
                conn.Close();
            }

            conn.Close();

        }

  //EDIT: if (lblLocationLabel.Text.Length > 0)
            {
                 ddlLocation.SelectedValue = lblLocationLabel.Text;
            }
    }  

So, I used an SqlDataReader and then I add the "Billers" to the list. Once that happens, I add the listItems to the Drop Down List.

What I had to do for it to select properly was Bind the text to a label, then say..

ddlLocation.SelectedValue = lblLabelLocation.Text;

Don't Forget to put the OnRowDataBound in your gridview properties as well. I hope this helps.

EDIT:

This is how I did it. I used an if statement to check to see if that label's text length is not blank (I have a blank field in my drop down) and if it does have text, then select or show the value.. I made the edit above but here it is again.

protected void gvVehicle_OnRowDataBound(object sender, GridViewRowEventArgs e)
    {
        foreach (GridViewRow gvr in gvVehicleTEMP.Rows)
        {
            DropDownList ddlLocation = ((DropDownList)gvr.FindControl("ddlLocation"));
            Label lblLocationLabel = ((Label)gvr.FindControl("lblLocationLabel")); //add this line to find the label

            conn.Close();
            conn.Open();

            SqlCommand cmdLocationNames = new SqlCommand("SELECT Name FROM Billers WHERE Store = '" + 1 + "' ORDER BY Name ASC", conn);
            List<string> internalLocationsList = new List<string>();

            using (SqlDataReader reader = cmdLocationNames.ExecuteReader())
            {
                while (reader.Read())
                {
                    string interlocations = reader.GetString(0);
                    internalLocationsList.Add(interlocations);
                }
                foreach (string locname in internalLocationsList)
                {
                    ddlLocation.Items.Add(new ListItem(locname));
                    conn.Close();
                }
                conn.Close();
            }

            conn.Close();

        }

      if (lblLocationLabel.Text.Length > 0)//Added if statement
            {
                 ddlLocation.SelectedValue = lblLocationLabel.Text;
            }
    } 

I use a templatefield like so.

<asp:TemplateField HeaderText="Location" SortExpression="Received">
           <ItemTemplate>
                  <asp:DropDownList ID="ddlLocation" runat="server" AutoPostBack="false">
                  </asp:DropDownList>
                  <asp:Label ID="lblLocationLabel" runat="server" Text='<%# Bind("Location") %>' Visible="false"></asp:Label>
                              <font size="2">Received On: </font>
           </ItemTemplate>
           <HeaderStyle Width="200px" />
</asp:TemplateField>

I hope this cleared it up a bit.

Answer 2

There are a couple of issues here:

1. You don't appear to be populating the DropDownList with id selResolutionSeverity and
2. Your FindControl() won't work at the parent control level (you need to first locate the row being updated)

I suggest you simplify the program by using data binding. If you are able to create a DataSource (eg SqlDataSource) for the severities, then you won't need to put any specific logic in the code behind. The following example assumes you have a SqlDataSource in your page called dsSeverities . If you don't wish to go down this route, then you could alternatively populate the DropDownList within a RowDataBound event handler.

<asp:TemplateField HeaderText="Severity">
 <HeaderStyle HorizontalAlign="Left" />
 <ItemTemplate>
   <%# Eval("ResolutionSeverity")%>
 </ItemTemplate>

 <EditItemTemplate>
   <asp:DropDownList  ID="selResolutionSeverity" runat="server"
     DataSourceID="dsSeverities"
     DataTextField="Description"
     DataValueField="ID"
     SelectedValue='<%# Bind("ResolutionSeverity") %>'  />
 </EditItemTemplate>
</asp:TemplateField>

Answer 3

You have to find the DropDownList in the GridViewRow which is in Edit mode on GridView 's OnRowDataBound event.

Here's how you can do this:

In markup add a method to GridView 's OnDtatBound. :

<asp:GridView ID="GridView1" runat="server" CellPadding="4" ForeColor="#333333" GridLines="None"
    ... ... ...
    OnRowDataBound="GridView1_RowDataBound" >

Now in the code write your GridView1_RowDataBound method write this code ( I would highly recommend replacing the query string with parameterized query to prevent possible sql injection) :

protected void GridView1_RowDataBound(object sender, System.Web.UI.WebControls.GridViewRowEventArgs e)
{
    //Make sure the row is in edit mode to find controls in EditItemTemlates
    if ((e.Row.RowType == DataControlRowType.DataRow) && ((e.Row.RowState & DataControlRowState.Edit) > 0))
    {

        var ddl = GridView1.FindControl("selResolutionSeverity") as DropDownList;
        if (ddl != null)
        {

            // Consider using parameterized query to prevent possible sql injection
            string sSQL = @"SELECT ErrorTypeLookupID as Value, ErrorDescription as DisplayText
                            FROM BabelFish.dbo.ErrorTypeLookup (NOLOCK)
                            WHERE ErrorType = 'Severity' ";

            DataSet DS = new DatabaseAccessing.DatabaseConnection().DS(sSQL);
            ddl.DataSource = DS;
            ddl.DataTextField = "DisplayText";
            ddl.DataValueField = "Value";
            ddl.DataBind();
            ddl.Items.Insert(0, new ListItem("-- Select --", "0"));
        }
    }
}