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Fill DropDownList dynamically in editable DataGrid

I am working with .NET ASP QuickStart tutorials. To see the sample I am talking about, please open this page:

http://samples.gotdotnet.com/quickstart/aspplus/doc/webdataaccess.aspx

Click link "DataGrid8.aspx [View Source]" and click link "CS\datagrid8.aspx". This sample shows how to use editable DataGrid. One of DataGrid columns is State which is edited as DropDownList. Appropriate code fragments from the file http://samples.gotdotnet.com/quickstart/util/srcview.aspx?path=/quickstart/aspplus/samples/webforms/data/datagrid8.src&file=CS\datagrid8.aspx&font=3

public Hashtable StateIndex;

...
         StateIndex = new Hashtable();
         StateIndex["CA"] = 0;
         StateIndex["IN"] = 1;
         StateIndex["KS"] = 2;
         StateIndex["MD"] = 3;
         StateIndex["MI"] = 4;
         StateIndex["OR"] = 5;
         StateIndex["TN"] = 6;
         StateIndex["UT"] = 7;
...
    public int GetStateIndex(String stateName)
    {
        if (StateIndex[stateName] != null)
            return (int)StateIndex[stateName];
        else
            return 0;
    }

...
        <asp:TemplateColumn HeaderText="state" SortExpression="state">
          <ItemTemplate>
            <asp:Label runat="server" Text='<%# DataBinder.Eval(Container.DataItem, "state") %>'/>
          </ItemTemplate>
          <EditItemTemplate>
            <asp:DropDownList runat="server" SelectedIndex='<%# GetStateIndex(DataBinder.Eval(Container.DataItem, "state").ToString()) %>' id="edit_State">
                  <asp:ListItem>CA</asp:ListItem>
                  <asp:ListItem>IN</asp:ListItem>
                  <asp:ListItem>KS</asp:ListItem>
                  <asp:ListItem>MD</asp:ListItem>
                  <asp:ListItem>MI</asp:ListItem>
                  <asp:ListItem>OR</asp:ListItem>
                  <asp:ListItem>TN</asp:ListItem>
                  <asp:ListItem>UT</asp:ListItem>
            </asp:DropDownList>
          </EditItemTemplate>
        </asp:TemplateColumn>
 
Both DropDownList and HashTable used to set initial selection are filled using hard-coded values. I want to change this sample and to fill DropDowmList dynamically from database. List of states may be read from database using the following SQL command:

select distinct State from Authors

In Page_Load I can read values from database table and keep them in HashTable or ArrayList. How can I populate dynamically DropDownList with these values? I tried to fill them using code inside asp:DropDownList tag, but compiler gives error:
Code blocks are not supported in this context
0
AlexFM
Asked:
AlexFM
  • 4
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2 Solutions
 
praneethaCommented:
do it in the itemDataBound event of a datagrid


if(e.Item.ItemType==ListItemType.EditItem && e.Item.ItemType != ListItemType.Header && e.Item.ItemType != ListItemType.Footer)
                  {
                        System.Web.UI.HtmlControls.HtmlSelect dList=(HtmlSelect)e.Item.FindControl("ddlColor");
dList.DataSource=ArrayList;
dlist.databind();                        
}

hope that works
0
 
sajayCommented:
You should cast the control to a drop down list and not an HTML select .. or what ever control you have use in the item template with the correct id

///event handler for the datagrid item databound
private void MyDataGrid_ItemDataBound(object sender,DataGridItemEventArgs e)
{

          if(e.Item.ItemType==ListItemType.EditItem && e.Item.ItemType != ListItemType.Header && e.Item.ItemType != ListItemType.Footer)
                         {
                              DropDownList dList=(DropDownList)e.Item.FindControl("edit_State");
                              dList.DataSource=ArrayList;
                              dlist.databind();                    
                              //you can set any property like selected item etc here.. or add new items here.

                         }

}
0
 
AlexFMAuthor Commented:
Thank you very much.
By the way, I cannot set SelectedItem inside of MyDataGrid_ItemDataBound (Why? I don't know). But I found solution of this problem and this is my code:

        public ArrayList States;

        private void Page_Load(object sender, System.EventArgs e)
        {
            myConnection = new SqlConnection("server=(local)\\NetSDK;database=pubs;Integrated Security=SSPI");

            if (!IsPostBack)
                BindGrid();

            States = new ArrayList();
            string mySelectQuery = "select distinct State from Authors";
            SqlCommand myCommand = new SqlCommand(mySelectQuery,myConnection);
            myConnection.Open();
            SqlDataReader myReader;
            myReader = myCommand.ExecuteReader();

            while (myReader.Read())
            {
                States.Add(myReader.GetString(0));
            }

            myReader.Close();
            myConnection.Close();
        }

        private void MyDataGrid_ItemDataBound(object sender, System.Web.UI.WebControls.DataGridItemEventArgs e)
        {
            if ( e.Item.ItemType != ListItemType.EditItem )
                return;

            Control c = e.Item.FindControl("edit_State");

            if ( c == null )
                return;

            DropDownList dList=(DropDownList)c;

            dList.DataSource = States;
            dList.DataBind();
        }

        public int GetStateIndex(String stateName)
        {
            System.Collections.IEnumerator myEnumerator = States.GetEnumerator();
            int i = 0;

            while ( myEnumerator.MoveNext() )
            {
                if ( myEnumerator.Current.ToString() == stateName )
                {
                    return i;
                }

                i++;
            }

            return 0;
        }


<asp:DropDownList runat="server" id="edit_State" SelectedIndex='<%# GetStateIndex(DataBinder.Eval(Container.DataItem, "state").ToString()) %>' />
0
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AlexFMAuthor Commented:
I want to ask additional question, I am sure you can answer it. After getting the answer I will open "Points for..." question.

Suppose I want to set SelectedIndex directly in MyDataGrid_ItemDataBound. It should look like this:

        private void MyDataGrid_ItemDataBound(object sender, System.Web.UI.WebControls.DataGridItemEventArgs e)
        {
            if ( e.Item.ItemType != ListItemType.EditItem )
                return;

            Control c = e.Item.FindControl("edit_State");

            if ( c == null )
                return;

            DropDownList dList=(DropDownList)c;

            dList.DataSource = States;
            dList.DataBind();

            System.Collections.IEnumerator myEnumerator = States.GetEnumerator();
            int i = 0;

            while ( myEnumerator.MoveNext() )
            {
                if ( myEnumerator.Current.ToString() == ??? )     // what should I write here instead of ???
                {
                    dList.SelectedIndex = i;
                    break;
                }

                i++;
            }
        }

How can I get recordset value to set current selection? Recordset contains string like "IN", "CA" etc. In my current solution it is extracted using
DataBinder.Eval(Container.DataItem, "state").ToString()
and passed to GetStateIndex function. How can I access this value directly from MyDataGrid_ItemDataBound function?
0
 
sajayCommented:
now .. as far as i get your code.. its to select a state.. depending on the value selected. right

now if your using v1.1 of the framework .. in asp.net you can do this

///event handler for the datagrid item databound
private void MyDataGrid_ItemDataBound(object sender,DataGridItemEventArgs e)
{

          if(e.Item.ItemType==ListItemType.EditItem && e.Item.ItemType != ListItemType.Header && e.Item.ItemType != ListItemType.Footer)
                         {
                              DropDownList dList=(DropDownList)e.Item.FindControl("edit_State");
                              dList.DataSource=ArrayList;
                              dlist.databind();                    

                              //you can set any property
                               DataRowView drv = e.DataItem;
                               DataRow dr= drv.Row;
                               dlist.SelectedValue = dr["MY_COLUMN_NAME"].ToString()
                         }
}


you can tweak anything you want from the e.DataItem.

this exposese the actual row view object that is bound to the row..
hope this answers your question.
0
 
sajayCommented:
sorry i missed out the casting

DataRowView drv = (DataRowView)e.DataItem

:)
cheers
0
 
AlexFMAuthor Commented:
System.Web.UI.WebControls.DataGridItemEventArgs' does not contain a definition for 'DataItem

for the line:
DataRowView drv = (DataRowView)e.DataItem;

I am working with VS 2003.
0
 
sajayCommented:
I guess its e.Item.DataItem ..

sorry about that
0
 
AlexFMAuthor Commented:
0
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