I have a dropdown box in my asp.net web page. I want the dd box to start out on load with "-- Select a Project --" as the text value. The dd box is bound to an EF object at design time -- no custom code (sorry). It has (like a classic Combo Box) an "ID" column (integer) and a display column. When I had a dd box with only one column, the process was simple:
protected void ProjectDropDown_DataBound(object sender, EventArgs e)
{
DropDownList list = sender as DropDownList;
if (list != null)
list.Items.Insert(0, "--Select a Project--");
}
Here is an image of the EF Datasource:
And Here's an image of the DropDownBox Properties...[ID is an Integer, ProjectNbr is a string]....:
And, since that's hard to read, here's a close-up:
But that doesn't work with a two-element dropdown box. Can anyone give me a hand?
Try this
protected void ProjectDropDown_DataBound(object sender, EventArgs e)
{
DropDownList list = sender as DropDownList;
if (list != null)
list.Items.Insert(0, new ListItem("--Select a Project--",""));
}
Use the ListControl.AppendDataBoundItems Property and set it to true:
AppendDataBoundItems Documentation
From the documentation: "The AppendDataBoundItems property allows you to add items to the ListControl object before data binding occurs. After data binding, the items collection contains both the items from the data source and the previously added items."
Related
I want to edit row of gridview.For that, I have added showeditbutton = true.I have binded gridview from cs file.Does I need to wite 3 function for that?(For editing I have added 3 function in cs file.).I have taken help from internet.But some point did not understand.
--In aspx
<asp:GridView datakeyname="Id" Id ="Gridview1" onRowEditing="GridView1_RowEditing" RowCancelingEdit=" GridView1_RowCancelingEdit" onRowUpdating ="GridView1_RowUpdating" >
<column>
// hyperlink ,dataTextfield is id
// some checkboxfield.(start from column 6)
</column>
protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
{
GridView1.EditIndex = e.NewEditIndex;
//code for Binding grid
}
protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
// for fetching value of id and checkboxfield(column 6)
string Id= GridView1.DataKeys[e.RowIndex].Values["Id"].ToString());
bool ischeck = (Gridview1.Rows[e.RowIndex].Cells[5].Controls[0] as checkBox).Checked;
// code for updating grid
GridView1.EditIndex = -1;
//Now bind the gridview gain here
}
protected void GridView1_RowCancelingEdit(object sender, GridViewUpdateEventArgs e)
{
GridView1.EditIndex = -1;
//Now bind the gridview gain here
}
Does am I going in right direction?What is use of datakey.Does I used properly?Why GridView1.EditIndex = -1 in update and cancel event.Column 6 is checkboxfield.why .Controls[0] is used for accessing that checkboxfield.
If you are using an ObjectDataSource (or SqlDataSource or OleDbDataSource) to databind and use UpdateCommand, DeleteCommand, InsertCommand, then you do not need to explicitly write those three functions for the edit/update operation. You need those functions when you are writing the binding code in code-behind or if you want to do additional work before/after any operation.
RowEditing fires when you click "edit" on the GridView. Here you specify what row to open in editmode by writing GridView1.EditIndex = e.NewEditIndex. You can also write code here to do any work that is required before user is put into editmode. For example, you can check for business rules conditions, and cancel the operation if rules are not met.
RowUpdating fires when you click "save"/"update" on the GridView. This is fired before the actual database operation. If you have an UpdateCommand on the datasource, then you do not need to write database save routine, otherwise you write that here.
DataKeys identify the "key" that identifies the data that is bound. You specify DataKeys while databinding to the GridView. For example, primary key of a database table. This line: string Id= GridView1.DataKeys[e.RowIndex].Values["Id"].ToString()); Here you are picking up the value of the "Id" key (you can have more than one keys) of the current row.
GridView1.EditIndex = -1 in update or cancel specifies that the GridView should no longer be in editmode. If this value is >= 0, then the GridView is put into editmode for that row (index starting from 0). So we set it to -1, to indicate that it should not be in editmode.
Controls[0] is used to pick the first control in that cell (you may have more than one controls). Alternatively, you can also use FindControl.
http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.gridview.sorting.aspx
This article deals with creating a datatable first, then creating a gridview from it, to aid in sorting. My predicament is slightly different.
I have a Gridview, that on Page_Load, I set the datasource to an ArrayList, and bind.
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
this.GridView1.DataSource = RequestManager.Instance.GetAllRequests();
this.GridView1.DataBind();
}
}
Now I would like to sort this GridView, so on the aspx page, I set AllowSorting="true", and OnSorting="GridView1_Sorting". So far, so good. I have the SortExpressions set in the BoundFields, and when I click on it, I know the _Sorting event is triggered.
Now, since this is a postback operation, I cannot simply cast the datasource of the gridview to a DataTable to sort. Saving to ViewState is an option, but I cannot figure out how to do it.
I would like to use the simple solution on this page, except for the DataTable not being available to me. Thanks for looking.
If you're able to target .NET v3.5, I recommend using Linq. In your _Sorting event handler, get the array list you did in the Page_Load and rebind it.
For example, if the type contained in the array list are MyType instances that have properties named Default and SomeField:
protected void Grid_Sorting(object sender, GridViewSortEventArgs e)
{
Func<MyType, object> keySelector;
if(e.SortExpresion == "SomeField")
{
keySelector = dataItem => dataItem.SomeField;
}
else
{
keySelector = dataItem => dataItem.Default;
}
ArrayList dataItems = RequestManager.Instance.GetAllRequests();
this.GridView1.DataSource = dataItems.OfType<MyType>().OrderBy(keySelector);
this.GridView1.DataBind();
}
That will get you started, then later inspect the sort expression to see if it ends with ASC or DESC and conditionally call .OrderByDescending(keySelector).
Finally, I don't recommend stashing the list in ViewState, as the ObjectStateFormatter is only optimized for a handful of types. http://msdn.microsoft.com/en-us/library/system.web.ui.objectstateformatter.aspx
Maybe consider ASP.NET cache instead.
I am using C# ASP.net, and relative new to it, and need to accomplish below.
In my VS2010 web application project I have webform with a Gridview which fetches the data from a table.
In the Grid, I have Commandfiled Button (column1) and Item template with Dropdownlist (column2).
Use case is, user first selects one listitem from 3 list items (H, L and M) and then selects command button.
I am not able to figure out how to extract selected listitem from a selected row
protected void GridView2_SelectedIndexChanged(object sender, EventArgs e)
{
GridViewRow row = GridView2.SelectedRow;
Label4.Text = "You selected " + row.Cells[4].Text + ".";
Label5.Text = "You selected this list item from dropdownlist " + ???? ;
}
Thanks in advance.
The GridViewRow object provides the method FindControl (as do all container controls) to get access to a control in the row by its id. For example, if your DropDownList has an id of MyDropDown, you could use the following to access its selected value:
GridViewRow row = GridView2.SelectedRow;
DropDownList MyDropDown = row.FindControl("MyDropDown") as DropDownList;
string theValue = MyDropDown.SelectedValue;
// now do something with theValue
This is the recommended method for accessing all controls in your GridView. You want to avoid doing things like row.Cells[#] as much as possible, because it easily breaks when you re-arrange or add/remove columns from your GridView.
i have a dropDownList which gets its data from a database. Now after the data has bound, i programmatically add another listItem to the ddl, like so:
protected void ddlEffects_DataBound(object sender, EventArgs e)
{
DropDownList ddl = dwNewItem.FindControl("ddlEffects") as DropDownList;
ddl.Items.Add(new ListItem("","0")); //Adds an empty item so the user can select it and the item doesnt provide an effect
}
It all works, but the problem is that the newly added listItem appears at the bottom of the DDL. I want it to be the first item. I tried making the value 0, but its still at the bottom. Is there any way to put it at the top?
Thanks!
Check into the ddl.Items.Insert method that will allow you to insert items at a specific location.
Like this for example:
using (Entities db = new Entities())
{
ddlDocumentTypes.DataSource = (from q in db.zDocumentTypes where (q.Active == true) select q);
ddlDocumentTypes.DataValueField = "Code";
ddlDocumentTypes.DataTextField = "Description";
ddlDocumentTypes.DataBind();
ddlDocumentTypes.Items.Insert(0, "--Select--");
ddlDocumentTypes.Items[0].Value = "0";
}
Which using EF loads the DDL with items for the database, and then inserts at position zero a new item.
What I'm looking for is a way to mimic the MS-Access style continuous form within asp.net. In one particular case, I want a control, bound to a datasource which returns a dropdownlist for each row, bound to the value within the datasource. Any change to any of the dropdownlists' would perform an update to the database instantly.
I have got halfway to achieving this using a repeater control, with the DropDownList.SelectedValue assigned within the Repeater.ItemDataBound event.
But now, supposing I add an OnSelectedIndexChanged event to the DropDownList - how would I then query the repeater to know which row I was on (to get the primary key value, for example)
I'm not sure this can be done easily.. so the question is what should I really be doing? I don't want to use a GridView that requires me to select a row to edit.. I just want to have the dropdownlists autopostback for any updates.
Hope that's clear?!
Cheers! :D
For examples sake, lets say we are binding to a custom class called Record
public class Record
{
public int Id;
public string Value;
}
If you put custom logic on the Repeater.OnItemCreated event you can attach the primary key to the id of the drop down list
protected void Repeater_ItemCreated(object sender, RepeaterItemEventArgs e)
{
if (!(e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem))
return;
var dataItem = e.Item.DataItem as Record;
if (dataItem == null) return;
var dropdown = e.Item.FindControl("myDropDown") as DropDownList;
if (dropdown == null) return;
dropdown.ID = dropdown.ID + dataItem.Id;
}
Then on the SelectedIndexChange, you can pull the id off of the dropdown that fired the event.
protected void SelectedIndexChanged(object sender, EventArgs e)
{
var dropdown = sender as DropDownList;
if (dropdown == null) return;
var stringId = dropdown.ID.Replace("myDropDown", "");
int id;
if (Int32.TryParse(stringId, out id))
{
updateRecord(id, dropdown.SelectedValue);
}
}
It's very much an ugly hack, but it should allow you to do what you want.
Easiest way to tackle this would be to mimic the Access continuous form ASP.NET style. Which would be to make a UserControl to handle the row-level UI, then put said UserControl in a repeater.