I created a new C# ASP.NET Web Application project in .NET 3.5
Then I dragged a button in my form.
In the property window the events symbol (yellow lightning bolt) does not show. When I double click the box next to 'OnClientClick' in the properties Window no default event handler is created. When I double click the button in design view no event handler is created either.
Any ideas on how I can get the events symbol and the automatic generation of a default event handler?
Perhaps you didn't have the option checked for "Place code in a separate file" when adding the webform? Also "OnClientClick" isn't a server side event, it is just a string property so it wouldn't ever map to a server side event handler.
Please check the tag that is being used for your control. If it looks like this:
<input type="submit" runat="server" value="OK" id="btn_1" />
then there will never be an Events symbol. Adding runat="server" to a regular HTML tag turns it into a rather basic Server'ified HTML control, with properties and events, yet Visual Studio does not recognize it as a control with events. (So events do exist, but you'll have to write all the necessary code and declarations yourself)
If the above is the case, rewrite it to this:
<asp:Button runat="server" Text="OK" id="btn_2" />
and then the Events symbol will be there. <asp:Button> creates a full featured Server Side Web Control, which in the end renders similar output, while offering a much richer set of features (such as Design mode support).
Related
Situation: I have been creating webpages in HTML5/CSS3 & Javascript using Sublime 2 text editor for a year, however a college course now requires me to use Asp.Net and Visual Studio 2010. I do not use the designer because I am proficient at doing things by hand, however I find that writing asp: inside every element is time consuming and causes syntax errors when applied to some HTML 5 tags and not others.
Example HTML 5: <button id="btn" type="submit" value="Button"/>
Example Asp.net: <asp:Button ID="Button1" runat="server" Text="Button" />
Question: Can the asp: portion be omitted without effecting anything or is it required for IIS or the C# back-end functionality? What about runat="server" can that be omitted?
Google has come up dry regarding my inquiry, so any help is appreciated.
you simply cannot remove either of the two
but hear me out why, because I have a feeling you are not familiar with ASP and therefor are mistaking the meaning of the asp: and the runat="server" syntax.
first: runat="server"
this property on an element, tells the the compiler that this is actually a server side control
so a <button/> is not the same as an <button runat="server"/>
the first one is pure html, while the second one is a control, which can be bound to on the server side. .Net will give it a clientID (not to be mistaken by the ID you have to give it yourself).
second: asp:
this is a prefix, on certain elements, that tells the compiler these are ASP controls (the default controls given by the ASP.net framework). These include Buttons, TextBoxes, DropDownLists, ...
do not mistake 1 of these with a html element.
an <asp:Button id="myAspButton" runat="server"/>
is not the same as a <button id="myHtmlButton"/>
the first, is a server side control, which can be bound to (see it's runat="server" attribute), and this control renders to the browser as a <input type="submit"/> for example.
you could alter the rendering of the asp.net button class to make it return something entirely differnt if you wish.
and you are also not limited to using asp.net classes.
you can create your own controls, and put them in a custom created library
you could give those your own prefix.
if I created such a custom control, I could register a prefix for it in the web.config file,
and thus I could create a custom button extending from the original one (but with a default label in front...
<myc:CustomButton ID="myButton" Text="myButton" Label="myLabel" runat="server"/>
which could render into:
<label>myLabel</label>
<button ID="*******">myButton</button>
the asterisks are symbolizing the Unique ID it will get from the .net framework
if you want to know more on custom controls, or extending default controls
here is a step by step explanation to create custom controls, or extend from a TextBox control.
it also shows how you add a custom prefix for your controls (in the this case 'cc')
you can find more info here
The runat="server" part is required to tell .NET that it will have to render a button there (which will contain .NET specific ID for processing upon POST). Not too familiar with web forms (I started with MVC), but I would assume that the asp: part is to help distinguish between server controls and standard HTML markup.
Why not try removing it and if it breaks something, then you know it's needed. For instance if the button doesn't show up after removing it, then obviously the .NET markup parser needs it to be there in order to know that it is a place holder for a server control.
I am trying to write a simple HTML form using asp.net and Jquery UI but am running into a problem when trying to process click event handlers on a button within this form. I was tryign to use OnClientClick and OnClick but once the clientside method gets accessed and returns the boolean the server side method is not called accordingly( not called at all actually)
Linky to code since I could not get the code tags to work properly: http://pastebin.com/LZNMqASt
I found the problem, Actually you are displaying "div#loginForm" element in to the dialog and its not taking the form element.
Put form element inside of "div#loginForm" container and the problem will be fixed.
For some reason the return type of the javascript method was not being accepted as a valid boolean. The below solution fixes the OnClientClick event
<asp:Button runat="server" ID="btnLogin" Text="Login" OnClick="btnLogin_OnClick"
OnClientClick="if(ValidateLoginForm() != true) return(false);" UseSubmitBehavior="False" />
The title pretty much precisely asks the question, but I shall repeat;
When I double click on a form control while in the design view in a Web Application project within Visual Studio 2010, say a 'button' or a 'submit' for example, it inserts a javascript function into my .aspx file. When I do this at work it automatically creates an event handler for the control in the code-behind.
How do I change this to that setting? I have used '/resetsettings' already, and other answers to similar questions do not solve my problem. I have reinstalled, gone through every menu I can find (though I may have missed something) and I'm pulling my hair out.
I don't want to type those event handler subroutines every time! Halp meee!
Thanks in advance for any helpful replies.
What it looks like is going on with this is that you are double clicking on a regular HTML element. For example, if you have
<input type="button" value="Test" id="Test" name="Test" />
and double click on it in design view it will create a JavaScript function on the page for it and an onclick event in the element. If you want to create an event handler in the code behind, you need to have an Asp.Net control like
<asp:Button runat="server" ID="Test" Text="Test" />
and then double click that to create a code event in the code behind.
Also, make sure that your page directive at the top has the correct filename for its CodeFile attribute to correctly map to an existing code behind file.
What is the difference in functionality between
<asp:Button id="button1" Text="Click me" runat="server" OnClick="submitEvent" />
and
<input type="button" id="button1" runat="server" value="Click me" />
Does the input with runat="server" attribute has other or limited properties and methods?
Thank you!
The first one creates a System.Web.UI.WebControls.Button while the second one creates a System.Web.UI.HtmlControls.HtmlInputButton.
Both are server controls, but the controls in the WebControls namespace generally has a bit more functionality than the controls in the HtmlControls namespace. Typically they put some data in ViewState to keep track of their state, and they have server side postback events.
Each controls in the HtmlControls namespace correspond exactly to an HTML element, while the controls in the WebControls namespace may be rendered differently depending on what the browser that is requesting the page can support.
The button represented by <asp:Button runat="server".../> will be converted to a web server control with a rich state model and different properties and methods which has more clear representation in real world like Button.Text = "Click Me".
The button represented by <input type="button" runat="server"..../> will be converted to html server control represented by HtmlInputButton; with has limited properties, methods and events. Most of the properties resemble the html equivalents like Button.Value="Click Me".
Note that elements in a markup page are pre-processed/compiled before being used and will be converted to a class representation where every element is represented by a control. You can access server side controls which are identified by the runat="server" tag from the code behind since they will have the correct matching server control(web/html), other static content including an <input type="button.../> tag with out the runat="server" will be represented as a LiteralControl.
The former line is ASP.NET, the latter simple XHTML.
The former gets parsed and interpreted on the server side, after which the HTML code is generated, which pretty much corresponds to your second example. The ASP.NET Button is really little more than light wrapper over th HTML input button functionality, and should be used wherever you need to handle the Click event on the server side (or in the general case any events), and is usually the way to go, since you're letting ASP.NET abstract the idea of a button on your page for you.
functionality of both the controls is same with the difference that first one is .net control and second one is html control that can be made servercontrol by using
runat="server".
and first one is rich in evants and metods thn the second one....
There is no server events associated with such a controls, but you can use it in codebehind to change it's properties.
Your second option won't probably even work. runat="server" will be rendered directly to the HTML output where it will have no functionality and will only break HTML validation.
input is an HTML element which has only HTML properties, and definitely no methods of any kind.
The following .NET 3.5 code, placed in an aspx file, will trigger a JavaScript error when the page is loaded (for users who have JavaScript enabled):
<noscript>
<asp:TextBox ID="txt" runat="server"></asp:TextBox>
<asp:RequiredFieldValidator ID="txt_RequiredFieldValidator" runat="server"
ControlToValidate="txt"></asp:RequiredFieldValidator>
<asp:Button ID="btn" runat="server" Text="Button" />
</noscript>
The error happens because the JavaScript generated by the ASP.NET validator control does not contain a null check on before the second code line below:
var ctl00_body_txt_RequiredFieldValidator =
document.all ?
document.all["ctl00_body_txt_RequiredFieldValidator"] :
document.getElementById("ctl00_body_txt_RequiredFieldValidator");
ctl00_body_txt_RequiredFieldValidator.controltovalidate = "ctl00_body_txt";
Can anyone suggest a workaround to this?
Footnote: Why am I doing this? For my non-JavaScript users I am replacing some AJAX functionality with some different UI components, which need validation.
You should add the following to the RequiredFieldValidator:
enableclientscript="false"
Seeing as you are using these in <noscript> tags, there is no point in supplying client side vaildation of the controls - they are only going to display if JS is turned off.
This will force the validation to happen (automatically) on the server side for you.
Just make sure you call "Page.IsValid" before you process the response.
See BaseValidator.EnableClientScript for more details.
The javascript is looking for an element contained in the noscript? AFAIK there's no clean way to detect script support from the server side.
I think you'll need to build in a redirect (I've seen this done with a meta-refresh in a header noscript if you don't mind a validation failure) to push noscript users to a "please turnscript on page" or do some surgery to loosen up the validation/control binding which may take some amount of wheel reinventing. This is one of those areas where asp.net's tight coupling between controller and view really punishes.