I was wondering if you guys could help me understand hidden fields, since I don't think I am getting them to work.
On the aspx page I have:
<asp:HiddenField ID="hidVal" value="" runat="server" />
On a button click I have a JavaScript function called
<button type="button" id="search" onclientclick="search_click()">Search</button>
With the function being
function search_click() {
document.getElementById('hidVal').Value = "1";
<% save(); %>
}
In aspx.cs I have a function that does this:
using (System.IO.StreamWriter file = new System.IO.StreamWriter(#"C:\Users\fgreene\Desktop\savedAdresses.txt", true))
{
file.WriteLine(hidVal.Value);
}
After clicking the button I look into the file and there is no change.
Is my approach correct or am I not understanding how this works?
Putting <% save(); %> in a JavaScript function in an aspx page causes save to be run when the page is built on the server, not when the surrounding JavaScript function is called on the client. At this point, the hidden field is empty, so your file gets a blank line written to it. When the user clicks the button, the hidden field is filled, but there's nothing to tell the server that this has happened.
What you need to do instead is something like:
// In your aspx, for the javascript function: remove the call to save,
// use the correct ID for the hidden field
function search_click() {
document.getElementById('<%= hidVal.ClientID %>').Value = "1";
}
// In your aspx in place of the button put
<asp:Button id="search" runat="server"
onclientclick="search_click(); return true;" onclick="search_click">
Search
</asp:Button>
// This results in a button that calls the javascript function on click, and
// then posts back to the server saying that the button has been clicked
// In your C#, this function gets called when the client posts back to
// say that the button has been clicked.
public protected void search_click(object sender, EventArgs e)
{
using (System.IO.StreamWriter file = new System.IO.StreamWriter(
#"C:\Users\fgreene\Desktop\savedAdresses.txt", true))
{
file.WriteLine(hidVal.Value);
}
}
You'll need to reference the client ID of the hidden field, which is probably not hidVal, as the actual client side ID generated in the HTML will be based on the parent control's naming container. There's two ways to fix this. First, you could make the client ID static on the control (which basically tells ASP.NET make the ID exactly what I said.):
<asp:HiddenField ID="hidVal" value="" ClientIDMode="Static" runat="server" />
Second, you can look up the ClientID property from the server when you generate your JavaScript:
document.getElementById('<%= hidVal.ClientID %>').Value = "1";
This would render out the actual client ID directly in the JavaScript code. Either approach is probably fine, but the second one would only work if the JavaScript is embedded directly in your ASPX file and not in a static .JS file.
Calling server side methods:
The second part of your question is about calling server side code when the button is pressed. You should do this by attaching an OnClick handler to your button:
<button runat="server" id="BtnSearch" onclientclick="search_click()" OnClick="btnSearch_Click">Search</button>
When the button is pressed, the page will be posted back and the btnSearch_Click event handler will be called. You'll then be able to handle any server side logic, as well as check the value of your hidden field. Hope this helps!
What you're trying to do is execute a server side function (save) via a client side call. This won't work as it is calling save() when the page first loads and then putting the return value (which is probably nothing) into the code where you put
<% save(); %>
Instead you need your button to fire the save function, but fire your javascript first. You do this by creating an asp:button (which renders as ) and then adding both an "OnClientClick" (for your javascript) and "OnClick" (for your server side function).
<asp:Button id="btnSearch" runat="server" OnClick="btnSearch_Click" OnClientClick="search_click()" text="Search" />
Then in your C# code you need the method to be named the same as the OnClick value:
protected void btnSearch_Click(object sender, EventArgs e)
{
using (System.IO.StreamWriter file = new System.IO.StreamWriter(#"C:\Users\fgreene\Desktop\savedAdresses.txt", true))
{
file.WriteLine(hidVal.Value);
}
}
The easiest way to create your server side function is to double click on the button in design view, as it will add the correct method call for you.
Hope this helps.
You can change hidden field value in both serverside and client side events.
Change value in client side
<script type="text/javascript">
function setvalue() {
document.getElementById('hidVal').value = "1";
}
</script>
<div>
<asp:HiddenField ID="hidVal" value="" runat="server" />
<br />
<asp:Button ID="Button1" runat="server" Text="Button" OnClientClick="setvalue();" />
</div>
Change value in serverside
<div>
<asp:HiddenField ID="hidVal" value="" runat="server" />
<br />
<asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click" />
</div>
protected void Button1_Click(object sender, EventArgs e)
{
hidVal.Value = "1";
}
Related
In my web application I need a functionality so that when users click on textbox to input values, it should make the button and the other fields visible?
I am using the code provided below but, could not get it working.
C#:
protected void TextBox1_Click(object sender, EventArgs e)
{
ButtonSearch.Visible = true;
}
ASP.NET:
<asp:TextBox ID="TextBox1" runat="server" OnTextChanged="TextBox1_TextChanged" OnClick="TextBox1_Click"></asp:TextBox>
<asp:Button ID="ButtonSearch" runat="server" OnClick="ButtonSearch_Click" Text="Search" Visible="False" />
How to accomplish this?
Set AutoPostback="True". This way the event will be fired server-side, and the button will become visible.
<asp:TextBox ID="TextBox1" runat="server" OnTextChanged="TextBox1_TextChanged" OnClick="TextBox1_Click" AutoPostBack="true"></asp:TextBox>
However, if you only want to toogle visility of a button, you really should considerate javascript. This will save a trip back to the server.
<asp:TextBox onclick="txtBox1_ClientClicked()" ID="TextBox1" runat="server" OnClick="TextBox1_Click"></asp:TextBox>
<asp:Button ID="ButtonSearch" runat="server" OnClick="ButtonSearch_Click" Text="Search" style="display:none;" />
<script type="text/javascript">
function txtBox1_ClientClicked(){
var theButton = document.getElementById('<%=ButtonSearch.ClientID%>');
theButton.style.display = 'block';
}
</script>
You do not need to post back to the server to accomplish your job. You can use client side onFocus event and javascript/jquery, for example.
I know I used an input of type text, and you are using an ASP Control which posts on server, but here is a JSFiddle to get you on the right track: http://jsfiddle.net/Mmjtz/1/
$("<%= ButtonSearch.ClientID %>").click(function(){
$("#TextBox1").show():
});
In this code you need to pass fields ID which you want to visible on the click of button.
Put the textbox inside a div and use the div's onClick event from codebehind. It's not what you asked but it works for me without any errors. Here is a javascript function to implement requested event:
function toggleVisibility()
{
document.getElementById('TextBox1').disabled = true;
/*
...some other code...
*/
}
And of course, you have to define your onclick event at the div definition after implementing this JS function.
<div id="TBdiv" onClick="toggleVisibility()">
<asp:TextBox ID="TextBox1"..../>
</div>
IMPORTANT: Since you now disabled your TextBox from codebehind, you have to enable it in somewhere before you want to use it again. Otherwise you will not see it while the page is running.
jQuery is the perfect solution for your problem. The code would be something like this:
$("#TextBox1").on("click",function(){$("#ButtonSearch").css("visibility", "visible");})
You include the script by adding <script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script> to the page and then you can add the piece of code above to within <script></script> tags.
I am unfamiliar with C#/ASP/.NET (learning as I go), so it is very likely that I am going about this in an inferior way, in addition to the problems with my current way of doing this. I will try to be as clear as possible (maybe overly so...).
I have a form with a textbox to take in a list of server hostnames, separated by line returns. Upon pressing the submit button, it uses PostBackUrl="~/btil_Info.aspx". In btil_info.aspx.cs codebehind, I get the info from said textbox (hostnames_tb) from the previous form in Page_Load() using:
string hostnames = ((TextBox)Page.PreviousPage.FindControl("hostnames_tb")).Text;
Within Page_Load(), I loop through this list of hostnames and build a form containing several fields for each host (a few textboxes and a dropdown menu for each host). After filling out these fields, upon pressing the Submit button here which calls Submit_Click() in the same codebehind, the page appears to reload because Page_Load is called again before Submit_Click() is executed. In doing so, the the filled form data is lost and the list of hostnames is also lost.
At an earlier stage in development, I had this all on the very first form page, and the submit button didn't call PostBackURL, it simply called Submit_Click(), which worked perfectly fine. The page didn't reload, the form stayed on the page, and I didn't lose data. But as it is now, the button works the same way. The only difference (that I see) being that this troublesome page is reached via the previous form calling PostBackURL.
I don't believe there's any point where anything should be requesting a page refresh/reload. I don't actually care if the page refreshes/reloads as long as the form data is posted and as long as the list of hostnames from the previous form is also retrievable. I just need to be able to access the form data and list of hostnames so that I can pass it to another method of mine that will update a SharePoint list (the code for that part is already working, though). I tried making the hostnames string a class variable in the 2nd codebehind (btil_Info.aspx.cs) and setting it as soon as soon as the page loads if it is empty, but apparently it does not persist over the page reload and is set back to null.
Here's some snippets of code that I hope will be of some help:
First page, add_BTIL.aspx:
<form id="form1" runat="server">
<div>
<asp:TextBox ID="hostnames_tb" runat="server" Rows="20" TextMode="MultiLine" Width="225px"></asp:TextBox>
<br />
<asp:Button ID="Submit" runat="server" PostBackUrl="~/btil_Info.aspx" Text="Submit" />
<br />
<asp:Literal ID="result" runat="server"></asp:Literal>
<br /><br />
<textarea id="hostnames_textarea" cols="25" rows="20" name="hostnames" title="Hostnames"></textarea></div>
</form>
First page codebehind, add_BTIL.aspx.cs:
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Submit_Click(object sender, EventArgs e)
{
string hostnames = hostnames_tb.Text;
/*
* Etc.
*/
}
Second page, btil_Info.aspx:
<form id="hosts_form" runat="server">
<p>
<asp:Button ID="Submit" runat="server" Text="Submit" OnClick="Submit_Click" Height="26px" UseSubmitBehavior="False" /><br />
<asp:Literal ID="result" runat="server"></asp:Literal><br />
</p>
<br />
</form>
^ In this form, I read somewhere in my searches that UseSubmitBehavior="False" would prevent a page reload, but it did not help. I didn't use it in my earlier version anyway, and did not have this issue.
Second page codebehind, btil_Info.aspx.cs:
protected void Page_Load(object sender, EventArgs e)
{
string hostnames = ((TextBox)Page.PreviousPage.FindControl("hostnames_tb")).Text;
// etc.....
}
protected void Submit_Click(object sender, EventArgs e)
{
// etc.....
}
Many thanks for any help!
If you're posting from add_BTIL.aspx to btil_Info.aspx then the Submit_Click function in file add_BTIL.aspx.cs will never be called.
Based on the limited markup you've given us for the btil_Info.aspx page...
If you aren't rendering your host names list inside of server controls inside the form id="hosts_form" then when you hit the submit button nothing is going to be posted to your Submit_Click function.
Personally I don't like post from one page to another so here are some suggestions below.
If you want to do a multi-page wizard then you might consider the asp.net wizard control.
Or if you want to keep it simple, use two asp Panel controls and show the first one, post the data, and then hide the first and show the second one.
How can I check whether a particular button was clicked or not in ASP.NET?
I think I need to perform some operation on Page_Load. This shouldn't be entering to Button_Click event to find. Is there any way that I can find where it was clicked or not on Client Side and take it to Page_Load?
Background: Basically __EVENTTARGET and __EVENTARGUMENT , These two Hidden controls are added to the HTML source, when ever any autopostback attribute is set to true for any of the web control.
The __EVENTTARGET hidden variable will tell the server ,which control actually does the server side event firing so that the framework can fire the server side event for that control.
The __ EVENTARGUMENT variable is used to provide additional event information if needed by the application, which can be accessed in the server.
So we can easily get the control causing postback using:Request.Params.Get("__EVENTTARGET");
PROBLEM:
The method: Request.Params.Get("__EVENTTARGET"); will work for CheckBoxes, DropDownLists, LinkButtons, etc.. but this does not work for Button controls such as Buttons and ImageButtons
The Button controls and ImageButton controls does not call the __doPostBack function. Because of this, the _EVENTTARGET will always be empty. However, other controls uses javascript function __doPostBack to trigger postback.
So, I will suggest to do something as below. Add an OnClientClick property to the buttons. Also, define a hiddenField in your Markup, whose value will contain the actual button causing postback.
<asp:Button ID="Button1" runat="server" Text="Button"
OnClientClick = "SetSource(this.id)" />
<asp:ImageButton ID="ImageButton1" runat="server"
OnClientClick = "SetSource(this.id)" />
<asp:HiddenField ID="hidSourceID" runat="server" />
On the OnClientClick property of the Button and ImageButton Call the SetSource JavaScript function
<script type = "text/javascript">
function SetSource(SourceID)
{
var hidSourceID =
document.getElementById("<%=hidSourceID.ClientID%>");
hidSourceID.value = SourceID;
}
</script>
Here onwards, you can very easily check in your Page_Load as to which Control caused postback:
if (IsPostBack)
{
string CtrlName;
CtrlName=hidSourceID.Value;
}
I just got the same trouble, have to do some logic judgement in the Page_Load method to treat different event(which button was clicked).
I realize the arm to get the as the following example.
The front end aspx source code(I have many Buttons with IDs F2, F3, F6, F12.
<Button Style="display: none" ID="F2" runat="server" Text="F2:Cancel" OnClientClick="SeiGyo(this)" OnClick="F2_Click" />
<Button Style="display: none" ID="F3" runat="server" Text="F3:Return" OnClientClick="SeiGyo(this)" OnClick="F3_Click" />
<Button Style="display: none" ID="F6" runat="server" Text="F6:Run" OnClientClick="SeiGyo(this)" OnClick="F6_Click" />
<Button Style="display: none" ID="F12" runat="server" Text="F12:Finish" OnClientClick="SeiGyo(this)" OnClick="F12_Click" />
The back end aspx.cs source code, what I need to do is judge which button was clicked when Page_Load was triggered. It seems a little stupid, but works.
In your situation, the button be clicked will be added into dic. I hope that will be helpful to some one.
Dictionary<string, string> dic = new Dictionary<string, string>();
foreach(var id in new string[]{"F2","F3","F6","F12"})
{
foreach (var key in Request.Params.AllKeys)
{
if (key != null && key.ToString().Contains(id))
dic.Add(id, Request[key.ToString()].ToString());
}
}
The UniqueID of the button will be in Request.Form["__EVENTTARGET"]
This question is already answered at: ASP.NET : Check for click event in page_load
You can try using the hidden field. Make the client side event on the OnclientClick event and try setting the value of hidden field, may be true or false depending on the condition.
And on the page load you can check the value of Hiidden field.
function click()
{
// set the hidden field here
}
And on the page load, simply check the value.
if(HiddenFieldName.Value=="true")
{
//perform the action
}
private bool button1WasClicked = false;
private void button1_Click(object sender, EventArgs e)
{
button1WasClicked = true;
}
if ( button1WasClicked== false)
{
//do somthing
}
The question is simple but I can't find a simple answer to it! .. btw I'll need to pass a QueryString to the page to be open.
Any ideas ?
You can actually link a javascript code into .NET with C#, below is an example, you could replace with your info, and push the parameters.
Response.Write("<script type='text/javascript'>window.open('Page.aspx?ID=" + YourTextField.Text.ToString() + "','_blank');</script>");
You can append on the end of it ?Field=your value passing&nextField=another value.
Is the answer to do this in javascript. As you make the underlying page in asp.net, provide it with the javascript to catch the buttons onclick event and call window.open(URL)
It depends on what you're trying to do but the simplest is to use the OnClientClick property of the Button. Take a look at http://msdn.microsoft.com/en-us/library/7ytf5t7k.aspx, in particular the details bout this property a little bit down.
Basically you'd do something like
<asp:Button ID="Button1" Runat="server"
OnClientClick="ShowPopup();"
Text="Test Client Click" />
With the JS to do your popup
<script type="text/javascript">
function ShowPopup() {
window.open('ThankYou.aspx');
}
</script>
You can also do both an OnClientClick and an OnClick if you need as well.
<asp:Button ID="Button1" Runat="server"
OnClick="Button1_Click"
OnClientClick="ShowPopup();"
Text="Test Client Click" />
Code behind
protected void Button1_Click(Object sender, EventArgs e)
{
Label1.Text = "Server click handler called.";
}
I have an ASP.NET web form where I have an hidden field, like this:
<form id="form1" runat="server" action="http://localhost/fa/Default.aspx">
<div>
<input id="requestData" type="hidden" name="requestData" value="" runat="server" />
<asp:Button ID="btnPOST" Text="POST" runat="server" OnClick="do_POST" />
</div>
</form>
On the method do_POST I have this:
protected void do_POST(object sender, EventArgs e)
{
//requestDataField is of the type protected global::System.Web.UI.HtmlControls.HtmlInputHidden requestData;
requestDataField.Text = "FOO!";
}
When I submit the form (by pressing the button), it goes to the server (an handler) wheer I have this:
string requestData = context.Request.Form["requestData"];
I get an empty string..
But if I assign a value like this:
<input id="requestData" type="hidden" name="requestData" value="FOO" runat="server" />
I get the "FOO"
What am I missing?
The reason why it's not doing it is because the method is called after the page has been post back. Meaning, it is actually working if you change .Text to .Value unfortunately by that time you have already read your form and it was an empty value. I remember working on a project where you could tell your form not to submit until a function has been run (but it was with a javascript that needed to run an complete before aspx submitted). You should try to see if there is a way to force your form to run your function BEFORE doing the postback.
Your do_POST method runs on the server, not on the client, and so is setting the value of the server-side object which represents the <input> control. Your context.Request.Form["requestData"] gets the value of the field from the client side data submitted in the POST request, which was never set, so it is blank.
If you want the onClick to be a client-side function, then you need to do it a little differently. Use the OnClientClick attribute (instead of onClick). Then create a javascript method to set the field value:
<asp:Button ID="btnPOST" Text="POST" runat="server" OnClientClick="do_POST" />
<script>
function do_POST() {
document.getElementById("requestData").value = "FOO!";
}
</script>
I tried your code and did few changes to it.
Change requestDataField.Text = "FOO!"; to requestData.Value = "FOO";
Also I added two buttons. One for do_POST function and the UseSubmitBehaviour property is set as False. The other one was to submit the form.
If you want to set it on client side then you will have to use Javascript.
Use "Value" instead of "Text" property for HtmlInputHidden control:
requestDataField.Value = "FOO!";
instead of
requestDataField.Text = "FOO!";