Programmatically access GridView columns and manipulate - c#

I have a GridView :
<asp:GridView ID="GridView1" runat="server" AllowPaging="True" GridLines="None"
HorizontalAlign="Left" AutoGenerateColumns="False"
DataSourceID="SqlDataSource1" onrowcommand="GridView1_RowCommand1">
<HeaderStyle HorizontalAlign="Left" />
<Columns>
<asp:TemplateField HeaderStyle-Width="150">
<HeaderTemplate>
<b>Downloads</b>
</HeaderTemplate>
<ItemTemplate>
<!-- <asp:HyperLink ID="hyperlinkDownload" runat="server" NavigateUrl="" >Download
MP3</asp:HyperLink> -->
<asp:LinkButton CommandName="download"
CommandArgument='<%# Eval("Name") %>' runat="server">Download MP3</asp:LinkButton>
</ItemTemplate>
</asp:TemplateField>
</asp:GridView>
I want to query the value of a particular field in a DB and if it's true, display the LinkButton. if false, I want the linkButton not to be displayed.
is there a way to access the GridView programmatically and make visible certain of its columns or manipulate its items ?
help.


You can do this by adding a handler to the RowDataBound event. Add an event handler along this lines of this in your code behind:
protected void myGrid_RowDataBound(Object sender, GridViewRowEventArgs e)
{
var data = e.Row.DataItem as DataRowView;
if (data != null)
{
var lbtDownload = e.Row.FindControl("lbtDownload");
lbtDownload.Visible = (bool) data.Row["HasFileForDownload"];
}
}
In your markup, attach the event handler to the grid:
<asp:GridView OnRowDataBound="myGrid_RowDataBound" ...>
You will also need to assign an id to the LinkButton, matching the one that you are search for using the FindControl() method in the event handler.
Disclaimer: I am on currently a Linux machine with no chance of testing this. Please report any bugs in the code - feel free to correct them if you have editor rights.


Yes there is.
1) You need to subscribe the RowDataBound event.
2) Give the LinkButton an ID.
3) Insert in codebehind
protected void GridView1_RowDataBound(Object sender, GridViewRowEventArgs e)
{
if(e.Row.RowType == DataControlRowType.DataRow)
{
LinkButton _bt = e.Row.FindControl("ID") as LinkButton;
if(_bt != null)
{
// have a look at the e.row.DataItem and try to get the value of your desired visibility property
_bt.Visible = true;
}
}
}
4) If this does not work with accessing the DataItem, start thinking about a LinqDataSource.

Related

OnCheckChanged Event of asp:CheckBox Not Firing When Unchecked From Within Nested GridView

I have conducted a lot of searches which included checkchanged or OncheckChanged keyword:
ASP.NET CheckBox does not fire CheckedChanged event when unchecking
https://forums.asp.net/t/1311576.aspx?Checkbox+not+firing+when+unchecking+using+OnCheckedChanged
OnCheckedChanged event not firing
OnCheckedChanged event handler of asp:checkbox does not fire when checkbox is unchecked
But this just doesn't seem to be working although I applied all suggestion from the links given above
I am tring to fire a CheckChanged Event From nested gridview, whose DataSource gets binded in parent grid's OnRowDataBound event.
My aspx markup
<asp:GridView ID="gvDocSchedule" runat="server" AutoGenerateColumns="false" CssClass="table table-striped color-black"
OnRowDataBound="gvDocSchedule_RowDataBound" DataKeyNames="UserID">
<Columns>
<asp:TemplateField>
<ItemTemplate>
<img alt="" style="cursor:pointer" src="UserPanel/images/Plus12.png" />
<asp:Panel ID="PanelSchedule" runat="server" Style="display:none">
<asp:GridView ID="gvScheduleDayNTime" runat="server" AutoGenerateColumns="false">
<Columns>
<asp:BoundField ItemStyle-Width="150px" DataField ="ScheduleDay" HeaderText="CheckInTime1"/>
<asp:BoundField ItemStyle-Width="150px" DataField ="CheckInTime1" HeaderText="CheckInTime1"/>
<asp:BoundField ItemStyle-Width="150px" DataField ="CheckOutTime1" HeaderText="CheckOutTime1"/>
<asp:BoundField ItemStyle-Width="150px" DataField ="CheckInTime2" HeaderText="CheckInTime2"/>
<asp:BoundField ItemStyle-Width="150px" DataField ="CheckOutTime2" HeaderText="CheckOutTime2"/>
<asp:TemplateField>
<ItemTemplate>
<asp:HiddenField ID="hdnForChkBox" runat="server" value="No" />
<asp:CheckBox ID="CBoxAvailabilityTime1" ViewStateMode="Enabled" Checked="false" Enabled="true" EnableViewState="true" runat="server" Text="See Free TimeSlots For Booking In Time1" AutoPostBack="true" OnCheckedChanged="CBoxAvailabilityTime1_CheckedChanged" />
<br />
<asp:CheckBox ID="CBoxAvailabilityTime2" runat="server" Text="See Free TimeSlots For Booking In Time1" AutoPostBack="true" OnCheckedChanged="CBoxAvailabilityTime2_CheckedChanged" />
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
</asp:Panel>
</ItemTemplate>
</asp:TemplateField>
<asp:BoundField ControlStyle-Font-Bold="true" DataField="UserFirstName" HeaderText="Doctor's First Name" />
<asp:BoundField DataField="UserLastName" HeaderText="Doctor's Last Name" />
<asp:BoundField DataField="SpecializationName" HeaderText="Doctor's Specialization" />
<asp:BoundField DataField="HospitalName" HeaderText="Hospital" />
</Columns>
</asp:GridView>
I was trying it with CBoxAvailabilityTime1CheckBox. As you guys can see ViewStateMode and EnableViewState has been taken care of not only in server tag but also in content page's tag, also these properties are true for master page
Parent Grid gets binded when user press a button and nested grid gets binded in parent's OnRowDataBound event
Here is My aspx.cs code
protected void CBoxAvailabilityTime1_CheckedChanged(object sender, EventArgs e)
{
foreach (GridViewRow gvParentRow in gvDocSchedule.Rows)
{
if (gvParentRow.RowType == DataControlRowType.DataRow)
{
GridView gvDocSchedulesGetChildGrid = (GridView)gvParentRow.FindControl("gvScheduleDayNTime");
if (gvDocSchedulesGetChildGrid != null)
{
foreach (GridViewRow gvChildRow in gvDocSchedulesGetChildGrid.Rows)
{
CheckBox CBoxAvailabilityTime1 = (CheckBox)gvChildRow.FindControl("CBoxAvailabilityTime1");
CheckBox CBoxAvailabilityTime2 = (CheckBox)gvChildRow.FindControl("CBoxAvailabilityTime2");
if (((CheckBox)CBoxAvailabilityTime1).Checked)
{
CBoxAvailabilityTime2.Enabled = false;
}
if (!((CheckBox)CBoxAvailabilityTime1).Checked)
{
CBoxAvailabilityTime2.Enabled = true;
}
}
}
}
}
}
With this setup CheckChanged Event Fires on Checking.
On Checking it hits Page_ Load skips if(!IsPostBack) (as AutoPostBack=true) and then control is directly transferred to
CBoxAvailabilityTime1_CheckedChanged(object sender, EventArgs e) event handler function
but on the other hand it doesn't fire on unchecking it postsbacks goes to Page load again Skips if(!IsPostBack) and does nothing instead of calling
CBoxAvailabilityTime1_CheckedChanged(object sender, EventArgs e)
"Note:-" Page_Load is not involved. I can't bind parent grid in page_load,
!IsPostBack because I dont need to bind it at first time when page gets loaded rather its binding happens inside a button click event, if a button is clicked only then parent grid must get binded.
Update 1:- This is how I bind data to parent grid
I am calling this function in a button click event
protected void BindDataToGridViewDocInArea()
{
using (SqlConnection con = new SqlConnection(constr))
{
con.Open();
SqlCommand cmdFillGridDocInArea = new SqlCommand("some query with parameter here", con)
cmdFillGridDocInArea.Parameters.AddWithValue("#AID", ddlAskArea.SelectedValue);
SqlDataAdapter sdaFillGridDocInArea = new SqlDataAdapter(cmdFillGridDocInArea);
DataTable dtFillGridDocInArea = new DataTable();
sdaFillGridDocInArea.Fill(dtFillGridDocInArea);
if (dtFillGridDocInArea.Rows.Count > 0)
{
gvDocSchedule.DataSource = dtFillGridDocInArea;
gvDocSchedule.DataBind();
}
else
{
lblError.Text = string.Empty;
lblError.Text = "No Record Exists Against Requst Specified";
}
con.Dispose();
}
}

Tested a stripped down version of you snippet. It seems to be working. When you check CBoxAvailabilityTime1, it disables CBoxAvailabilityTime2. When you uncheck CBoxAvailabilityTime1 the other one is enabled again.
However this is only when the DataBinding of gvDocSchedule is inside an IsPostBack check. When it's not the checkboxes will always go to their default unchecked state after PostBack.
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
//this works
gvDocSchedule.DataSource = LoadFromDB();
gvDocSchedule.DataBind();
}
//this does not
gvDocSchedule.DataSource = LoadFromDB();
gvDocSchedule.DataBind();
}
Or in your case something like this:
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
BindDataToGridViewDocInArea();
}
}

how to get value of a template field label of a gridview, getting error Object reference not set to an instance of an object

While getting the value I'm getting Object reference not set to an instance of an object. how to get labeled label value in code behind. How to get the value in custom event
<asp:GridView runat="server" ID="gridviewQuoteDetails" EmptyDataText="No records Found..." AutoGenerateEditButton="false" OnRowEditing="gridviewQuoteDetails_RowEditing" OnRowUpdating="gridviewQuoteDetails_RowUpdating" DataKeyNames="id" AutoGenerateColumns="false">
<Columns>
<asp:TemplateField>
<ItemTemplate>
<a href='Quote.aspx?val=<%#Eval("id")%>'>
<asp:Label ID="lblid" runat="server" Text='<%#Eval ("id")%>'></asp:Label>
</a>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField>
<ItemTemplate>
<asp:LinkButton ID="LinkButton1" Text="Edit" runat="server" CommandName="Edit" />
</ItemTemplate>
<EditItemTemplate>
<asp:LinkButton ID="LinkButton2" Text="Update" runat="server" OnClick="OnUpdate" />
</EditItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
code behind
protected void OnUpdate(object sender, EventArgs e)
{
string qouteid = ((Label)gridviewQuoteDetails.FindControl("lblid")).Text;
GridViewRow row = (sender as LinkButton).NamingContainer as GridViewRow;
string id = (row.Cells[0].Controls[0] as TextBox).Text;
string Description = (row.Cells[1].Controls[0] as TextBox).Text;
}

Gridview is a collection of rows right, but you are trying to search the control directly within the gridview thus ((LinkButton)gridviewQuoteDetails.FindControl("lbllnknm")) will be null and when you are trying to access the Text property of LinkButton you are getting NRE error.
You need to loop through the rows of your gridview control to access each linkbutton present in each row like this:-
foreach (GridViewRow row in gridviewQuoteDetails.Rows)
{
LinkButton lbllnknm= row.FindControl("lbllnknm") as LinkButton;
}
But ideally you would not be needing this. I guess you are trying to get the value in OnRowEditing event handler. If that is the case then you can fetch the value of linkbutton like this:-
protected void gridviewQuoteDetails_RowEditing(object sender, GridViewUpdateEventArgs e)
{
string qouteid = ((Label)gridviewQuoteDetails.Rows[e.NewEditIndex]
.FindControl("lbllnknm")).Text;
}
Update 2:
As per your comment you are trying to access the LinkButton text on click of LinkButton itself which means the event is raised by LinkButton itself. You can simply use the sender object like this:-
protected void OnUpdate(object sender, EventArgs e)
{
LinkButton LinkButton2 = sender as LinkButton;
GridViewRow row = LinkButton2.NamingContainer as GridViewRow; //Get the gridview row
Label lblid = row.FindControl("lblid") as Label;
string qouteid = lblid.Text;
}

How can I hide asp controls or div tags that are inside a asp:GridView

I have this ASP:GridView and I cant seem to be able to declare the asp controls or div tags inside this ASP:GridView in my codebehind ascx file.
<asp:GridView runat="server" ID="siteMembersView" AllowPaging="True"
ShowHeader="False" EnableModelValidation="True" AutoGenerateColumns="false" CssClass="membership-gridview" Width="100%" CellPadding="0" CellSpacing="0">
<Columns>
<asp:TemplateField>
<ItemTemplate>
//content
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
I am trying to put Mydiv.Visible = false and LinkButton.Visible = False
But it cant find the IDs. I am using runat="server". I think the problem is that its inside the GridView beacuse I tried to put it outside the GridView and it worked perfectly.
Any kind of help is appreciated

Use the FindControl method to access your controls, then you can apply the logic to toggle the visibility of each:
How to find control in TemplateField of GridView?
protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
HtmlGenericControl myDiv;
LinkButton myLinkButton;
if(e.Row.RowType == DataControlRowType.DataRow)
{
myDiv = (HtmlGenericControl)e.Row.FindControl("myDiv")
as HtmlGenericControl;
myDiv.Visible = false;
myLinkButton = (LinkButton )e.Row.FindControl("myLinkButton")
as LinkButton;
myLinkButton.Visible = false;
}
}

How to get datatextfield value

I am making a web site in visual studio 2012, using asp.net, c#.
I created a grid view, which is taking data from my sql server, and created a button field which is bound to id_p, which is one of the collumns taken from a database. I am trying to get the data of the id_p for the row in which the button was clicked.
<asp:ButtonField ButtonType="Button" DataTextField="id_p"
DataTextFormatString="Stavi u košaricu" Text="Button1" />
What I need is not the selected row, only the id_p value, so how could I do that, please?

You need to handle the OnRowCommand Event on the gridview as so:
<asp:GridView ID="GridView1" runat="server" OnRowCommand="GridView_RowCommand"
And create a ItemTemplateField to display a regular <asp:button> instead of using the ButtonField column:
<asp:TemplateField>
<ItemTemplate>
<asp:Button ID="btn" runat="server"
CommandName="Something" CommandArgument='<%#Eval("id_p") %>'
Text="Stavi u košaricu" />
</ItemTemplate>
</asp:TemplateField>
Now you handle the RowCommand Event:
protected void GridView_RowCommand(Object sender, GridViewCommandEventArgs e)
{
string m_id = e.CommandArgument.ToString();
if (e.CommandName == "Something")
{
//do something with m_id
}
}

Full postback triggered by LinkButton inside GridView inside UpdatePanel

I have a GridView inside of a UpdatePanel. In a template field is a button I use for marking items. Functionally, this works fine, but the button always triggers a full page postback instead of a partial postback. How do I get the button to trigger a partial postback?
<asp:ScriptManager ID="ContentScriptManager" runat="server" />
<asp:UpdatePanel ID="ContentUpdatePanel" runat="server" ChildrenAsTriggers="true">
<ContentTemplate>
<asp:GridView ID="OrderGrid" runat="server" AllowPaging="false" AllowSorting="false"
AutoGenerateColumns="false">
<Columns>
<asp:TemplateField HeaderText="">
<ItemTemplate>
<asp:LinkButton ID="MarkAsCompleteButton" runat="server" Text="MarkAsComplete"
CommandName="MarkAsComplete" CommandArgument='<%# Eval("Id") %>' />
</ItemTemplate>
</asp:TemplateField>
<asp:BoundField DataField="Name" HeaderText="Name" />
<asp:BoundField DataField="LoadDate" HeaderText="Load Date" />
<asp:BoundField DataField="EmployeeCutOffDate" HeaderText="Cut Off Date" />
<asp:BoundField DataField="IsComplete" HeaderText="Is Completed" />
</Columns>
</asp:GridView>
</ContentTemplate>
</asp:UpdatePanel>

You need to register each and every LinkButton as an AsyncPostBackTrigger. After each row is bound in your GridView, you'll need to search for the LinkButton and register it through code-behind as follows:
protected void OrderGrid_RowDataBound(object sender, GridViewRowEventArgs e)
{
LinkButton lb = e.Row.FindControl("MarkAsCompleteButton") as LinkButton;
ScriptManager.GetCurrent(this).RegisterAsyncPostBackControl(lb);
}
This also requires that ClientIDMode="AutoID" be set for the LinkButton, as mentioned here (thanks to Răzvan Panda for pointing this out).

It's probably not advised but you can make everything on the GridView work asynchronously by excluding the EventName on the AsyncPostBackTrigger so e.g.
<Triggers>
<asp:AsyncPostBackTrigger ControlID="OrderGrid" />
</Triggers>
This will make the RowCommand event and any other event on the GridView fire asynchronously. Note as well that when you make ClientIDMode="Static" on the GridView it will cause a full postback.

My grid view is in conditional mode.
protected void gvAgendamentoExclui_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow) {
LinkButton lnk = e.Row.FindControl("LinkButton2") as LinkButton;
AsyncPostBackTrigger trigger = new AsyncPostBackTrigger();
trigger.ControlID = lnk.UniqueID;
trigger.EventName = "Click";
UpdatePanel2.Triggers.Add(trigger);
}
}
And in the click event of the linkbutton I put:
protected void LinkButton2_Click(object sender, EventArgs e)
{
UpdatePanel2.Update();
}

Put the following element inside system.web element in web.config file
<xhtmlConformance mode="Transitional"/>

MSDN specifies that the UpdatePanel.ChildrenAsTriggers property "[g]ets or sets a value that indicates whether postbacks from immediate child controls of an UpdatePanel control update the panel's content" (see http://msdn.microsoft.com/en-us/library/system.web.ui.updatepanel.childrenastriggers.aspx).
Since your LinkButton does not appear to be an "immediate child control," then I would recommend configuring your LinkButton as an explicit AsyncPostBackTrigger.
Below your </ContentTemplate> tag, try adding this:
<Triggers>
<asp:AsyncPostBackTrigger ControlID="MarkAsCompleteButton" EventName="Click" />
</Triggers>

I had an issue where I had one form working fine (page1), another doing whole post backs (page2). Turned out when I made the 2nd page, I had done a bit too much cut/paste, and it still had a javascript call in the form definition.
< form id="form1" runat="server" onsubmit="return checkstuff();">
But checkstuff was not defined in page 2.
deleted the onsubmit, and the partial posts started working.
In the working page - page 1, checkstuff was defined, but was just a stub, which did nothing more than return true. Just for grins, I put an alert in checkstuff, and sure enough, it is called for all submits, partial or not. And, if I changed the stub to just return false, nothing happened at all.
Point in all this, the javascript is still exercised, as if a full page is being submitted. So double check your client side scripts.

this may be old but my solution was to put an update panel inside the itemTemplate and one outside the gridview as well.
the trigger should be the gridview and the outside trigger should be the gridview and PageIndexChanging. Try that.

You need to register each controls for each RowState.
1: Register your controls for RowState = Alternate and Normal)
2: Register your controls for RowState = Edit
3: ...
ASPX:
<asp:TemplateField HeaderText="">
<ItemTemplate>
<asp:LinkButton runat="server" ID="Btn1"
CommandName="Edit" CommandArgument='<%# Container.DataItemIndex + ";" + Eval("idinterlocuteur") %>'><i class="fa fa-pencil-square-o"></i></asp:LinkButton>
</ItemTemplate>
<EditItemTemplate>
<asp:LinkButton ID="Btn2" runat="server" CommandName="Update" CommandArgument='<%# Container.DataItemIndex + ";" + Eval("idinterlocuteur") %>'><i class="fa fa-check"></i></asp:LinkButton>
</EditItemTemplate>
</asp:TemplateField>
Code behind :
protected void GridView_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow
&& (e.Row.RowState == DataControlRowState.Normal
|| e.Row.RowState == DataControlRowState.Alternate))
{
LinkButton Btn1 = e.Row.FindControl("Btn1 ") as LinkButton;
ScriptManager.GetCurrent(this.Parent.Page).RegisterAsyncPostBackControl(Btn1 );
}
if (e.Row.RowType == DataControlRowType.DataRow
&& e.Row.RowState == DataControlRowState.Edit)
{
LinkButton Btn2 = e.Row.FindControl("Btn2 ") as LinkButton;
ScriptManager.GetCurrent(this.Parent.Page).RegisterAsyncPostBackControl(Btn2 );
}
}

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