I have a asp.net page content as below. There is an HtmlInputText control inside a Panel which has Enabled="false". I set the Value property of HtmlInputText control in btnSet_Click and then set Enabled=true for the panel. After the postback finishes Value of the HtmlInputText is lost. Below is a list of cases i tried:
When I use asp:TextBox instead of HtmlInputText it works fine. But the above is a simplified demonstration of the usage of a complex user control. Basically, changing it is not an option.
When I place the panel and the buttons in an asp:UpdatePanel, it works fine again.
When I set disabled="disabled" (in the markup) for the HtmlInputText control, it works fine yet again.
What may be the cause of this behaviour?
<asp:Panel ID="pnl" runat="server" Enabled="false">
<input type="text" runat="server" id="txt" />
</asp:Panel>
<asp:Button ID="btnSet" runat="server" Text="Set" OnClick="btnSet_Click" />
<asp:Button ID="btnEnable" runat="server" Text="Enable" OnClick="btnEnable_Click" />
--
protected void btnSet_Click(object sender, EventArgs e)
{
txt.Value = "Test";
}
protected void btnEnable_Click(object sender, EventArgs e)
{
pnl.Enabled = true;
}
Actually the HTML server controls (eg:) have no mechanism of identifying the capabilities of the client browser accessing the current page.
But the Web server controls(eg:asp:TextBox) will not have browser compatibility issues as it takes care of itself.
Web server controls give u more freedom, flexibility and control over behaviour of these controls... so use them for your purpose.
Related
I'm using an aspx file as my main page with the following code snippet:
<input type="text" runat="server" id="Password" />
<asp:Button runat="server" id="SavePassword"
Text="Save" OnClick="SavePassword_Click"/>
Then in the code behind I use:
protected void SavePassword_Click(object sender, EventArgs e)
{
string a = Password.Value.ToString();
}
Setting Password.Value in the Page_Load works as expected, but setting a to the value results in an empty string in a regardless what I type in on the page befoere I click the save button.
Am I overlooking here something?
You should add label field with name labelShow in aspx page like this
<asp:Label ID="labelShow" runat="server"></asp:Label>
Then add the string into .cs file
protected void SavePassword_Click(object sender, EventArgs e)
{
string a = Password.Value.ToString();
labelShow.Text = a.ToString();
}
I can figure several errors :
You say something about Page_Load. You should always remember Page_Load is executed at every postback. So if you write something into the textbox at Page_Load, it will erase the value typed by user. You can change this behavior by veriyfing
if(!IsPostBack)
{
// Your code
}
around your Page_Load content.
input runat="server" is not the proper way to do TextBox in ASP.Net, in most cases you should use asp:TextBox
You don't do anything with your "a" string, your current code sample does nothing, whether the Password field is properly posted or not. You can do as suggested by Ravi in his answer to display it.
I suggest you to to learn how to use VS debugger, and to read a good course on ASP.Net Webforms to learn it.
To avoid unwarranted "duplicate" flagging, let me say upfront - I have searched high and low for an answer and only found ones like this, which has no answer, or this, which tells me to use MyControl.Focus(); from my code behind. That does not work properly. I will explain.
I have a series of dropdown controls in an update panel, each of which affects the ones after it - City, Building and Room. When the user changes the selection in the city dropdown, mouse or keyboard, focus is immediately lost as the page does the partial postback. Ok, so I try to put in the CityListDropDown.Focus();, but that causes the page to reposition itself so that this control is at the bottom of the visible area of the page - not the desired behavior. The page should not move at all. Mind you, this only matters if you have a lot of other stuff on the page before your update panel, so that these prompts are lower down where the page has had to scroll down to them.
So, how do I restore focus back to that city drop down so when the user is using the keyboard, they can just keep on trucking to the next prompt? Same goes for the building drop down.
Here is my html:
<asp:UpdatePanel ID="RoomsUpdatePanel" runat="server" UpdateMode="Conditional" RenderMode="Inline">
<ContentTemplate>
<asp:DropDownList ID="CityListDropDown" runat="server" class="form-control input-sm" Width="140" AutoPostBack="True" OnSelectedIndexChanged="CityListDropDown_SelectedIndexChanged">
</asp:DropDownList>
<asp:DropDownList ID="BuildingListDropDown" runat="server" class="form-control input-sm" AutoPostBack="True" Width="100" OnSelectedIndexChanged="BuildingListDropDown_SelectedIndexChanged">
</asp:DropDownList>
<asp:DropDownList ID="RoomListDropDown" runat="server" class="form-control input-sm" AutoPostBack="False" Width="175">
</asp:DropDownList>
</ContentTemplate>
</asp:UpdatePanel>
and here is my code behind:
protected void CityListDropDown_SelectedIndexChanged(object sender, EventArgs e)
{
LoadBuildingList();
LoadRoomList();
CityListDropDown.Focus();
}
protected void BuildingListDropDown_SelectedIndexChanged(object sender, EventArgs e)
{
LoadRoomList();
BuildingListDropDown.Focus();
}
If you don't want the page to scroll / get repositioned whenever the focus is changed, you can use the PageMaintainScrollPositionOnPostback property of the Page directive :
<%# PageMaintainScrollPositionOnPostback="true" ... %>
or you can try setting it programatically through code :
Page.MaintainScrollPositionOnPostBack = true;
I got it! So using the code behind Focus() method of the control causes the page to reposition itself, even when you have set the MaintainScrollPositionOnPostBack property of the page to true. But, javascript can change focus without moving the page around unnecessarily. So if I need to reset focus from my code behind, to the sending control, I can do this:
protected void CityListDropDown_SelectedIndexChanged(object sender, EventArgs e)
{
LoadBuildingList();
LoadRoomList();
ScriptManager.RegisterStartupScript(CityListDropDown, CityListDropDown.GetType(), "CityDropDownRefocus", "document.getElementById(\"" + CityListDropDown.ClientID + "\").focus();", true);
}
or, if I want that line of code that resets the focus to be more generic (say I have an event handler that is used by multiple controls, and I need the handler to reset focus to the control that generated the postback, the handler is going to get the sending object, so I can say:
protected void MyControlHandler(object sender, EventArgs e)
{
...
ScriptManager.RegisterStartupScript((WebControl)sender, sender.GetType(), "CityDropDownRefocus", "document.getElementById(\"" + ((WebControl)sender).ClientID + "\").focus();", true);
}
And that resets the focus back to the sending control, without moving the page around!
This seems like an elementary issue but it has me stumped.
I have a main page which loads a custom control (.ascx) on page_load.
This custom control has two fields. One of them being a dropdownlist and the other being a text box. When the dropdownlist changes value it triggers a post back, some logic is executed server side and a value is generated for the textbox. I stepped through the code and the value is created and assigned correctly. However, when the page is rendered the value does not change.
If I change the textbox value to "QQQ" and trigger the postback, "QQQ" stays in the textbox so I can verify viewstate is working.
Is there any reason why the generated value is not being displayed in the form on postback. This process works fine on the initial page load.
.aspx.cs
protected void Page_Load(object sender, EventArgs e)
{
string ascxPath = #"~/_CONTROLTEMPLATES/TRC_BITS.ascx";
TRC_BITS control = Page.LoadControl(ascxPath) as TRC_BITS;
phForm.Controls.Add(control);
}
.ascx
<asp:TextBox ID="message" runat="server" TextMode="MultiLine" /><br/>
<asp:DropDownList ID="year" runat="server" AutoPostBack="true">
<asp:ListItem Text="2011">2011</asp:ListItem>
<asp:ListItem Text="2012">2012</asp:ListItem>
<asp:ListItem Text="2013">2013</asp:ListItem>
</asp:DropDownList>
.ascx.cs
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
year.SelectedValue = DateTime.Now.Year.ToString();
}
if (year.SelectedValue == 2012)
message.Text = "ABC";
else
message.Text = "XYZ";
}
Because you're adding these controls to the page dynamically, you need to assign an ID to the user control. Make sure to assign the same ID to the controls every time the page is posted back, and the fields will be repopulated from ViewState.
Also, as Shai suggested, it would be more appropriate if you loaded the controls during OnInit instead of Page_Load. The situation is a little different with user controls, but in general you want to add your dynamic content before the LoadViewState method is executed.
If you're looking for something to take the pain out of persisting dynamic content, I would suggest taking a look at the DynamicControlsPlaceHolder.
Because you are adding the controls dynamically, you need to add them during the page's oninit event.
Try it, believe me. Go for it. Yalla.
I have a custom UserControl which contains several TextBoxes with Validators. One TextBox with corresponding Validator is optional based on a CheckBox. Pseudo:
My Control.ascx:
<asp:TextBox id="txtAddress" />
<asp:Validator id="valAddress" />
<asp:CheckBox id="condition" />
<asp:TextBox id="txtConditional" />
<asp:Validator id="valConditional" ValidationGroup="ConditionalGroup" />
My Control.ascx.cs
public void Validate() {
if(condition.Checked) {
Page.Validate("ConditionalGroup");
}
}
I also have a page which basically looks like this:
Page.aspx
<my:Control id="myControl" />
<asp:Button onClick="doPost" />
Page.aspx.cs
protected void doPost(object sender, EventArgs e) {
myControl.Validate(); //This feels wrong
if(Page.IsValid) {
//go
}
}
This all works, however I would like to take the myControl.Validate() line out of the Page.aspx.cs and put it in the My Control.ascx.cs. Putting it in the Page_Load of the control is not an option because the conditional checkbox value is always false. There is no event available after Page_Load and before the doPost click handler is fired...
It feels wrong to call the custom Validate function on the Page where I think it should belong somewhere in the UserControl. Is it true that this is architecturally wrong? Is there another solution for this maybe by using an event handler?
You could try by enabling the validator only if the user checks on the check box. And disable the validator if the unchecks it. This has to be done in the user control. It can be done in the client side or in the server side. In this way, the page would validate all the validators that are enabled for the page.
I have a user control embedded in a web part. It has the following snippets of code:
protected TextBox searchTextBox;
protected Button goButton;
protected Button nextButton;
protected Repeater pushpins;
protected Label currentPageLabel;
protected void goButton_Click(object sender, EventArgs e)
{
// Do stuff
}
<asp:TextBox ID="searchTextBox" runat="server" />
<asp:Button ID="goButton" runat="server" Text="Go" OnClick="goButton_Click" />
<asp:Repeater ID="pushpins" runat="server" EnableViewState="false">
<ItemTemplate>Blah</ItemTemplate>
</asp:Repeater>
<asp:Label ID="currentPageLabel" runat="server" />
<asp:Button ID="nextButton" runat="server" Text=" >> " OnClick="nextButton_Click" />
(There is no OnLoad or CreateChildControls method.)
If I place a breakpoint on the first line of goButton_Click, I find:
searchTextBox: initialised
goButton: initialised
nextButton: NULL
pushpins: initialised
currentPageLabel: NULL
Why are some controls initialised and others not? How do I get around this if I'd like to update the Text property on currentPageLabel?
Update:
I've placed breakpoints all the way through the page life cycle and found that nextButton and currentPageLabel are never initialised. The breakpoints were placed at OnLoad, CreateChildControls, goButton_Click, OnPreRender, Render and OnUnload.
Is it possible you've inadvertently got local variables named currentPageLabel and/or nextButton declared somewhere? The compiler will happily allow this...
This is especially common in a move from ASP.NET 1.1 to 2.0 or higher, since the way the designer defined these controls changed.
The problem was that all of the controls that weren't being initialised were inside a HeaderTemplate within a Repeater control. (To save space I didn't paste all of my code into the question, dang it.)
I moved them out and the problem is resolved. Obviously controls in the HeaderTemplate are instantiated by the Repeater and do not follow the normal page life cycle.