I'm a new comer to ASP.NET. Before that, I was a classic ASPer.
As I know:
ViewState use to maintain some complicate-property(sorry for my arbitrary description.Only to differentiate basic property like value).
ViewState go with PostData and back to server in PostBackData.
ViewState record the latest control status. Compare it with PostData to determine if a event should be fire like SelectedIndexChange.
WebForm is Event base and disable ViewState this engine failed. But ViewState could be mighty.
On some well-known Asp.Net sites like
https://stackoverflow.com/
http://www.codeproject.com/
when I look over source code.I can't see something like
<input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="31zA00LgYW9+3QuC4YmxF4w3eBAWhuZRL89OB+6X4AwCFpYIR2914D5a4PWubGveAods0+i/2T21mmpYlHx/sv+5gsGfyYPd0bhj76B0yy4=" />
Does those websites never use a runat="Server" and disable ViewState?
If so, I don't Know the reason to use WebForm when throw away ViewState. Why not MVC?
Related
Should I use ASP elements with a runat="server" attribute or an HTML form?
It seems like using ASP tags such as <asp:TextBox> is much more comfortable since I don't have to redirect the user to another page on a form submition, but also from what I've seen, it seemed like HTML forms are the more accepted way. I was starting to wonder if using ASP elements increases server load or has any other disadvantage?
In case I should use ASP elements, how do I validate the input with Javascript before sending it to the server?
In case I should use HTML forms, how do I not redirect the user on submition and also not run the server code on page load?
You can easily use the HTML5 input type in Web Forms by adding the runat="server" attribute, so that it can be accessed on the server-side:
<label for="name">Name:</label>
<input type="text" id="name" name="name" required
minlength="4" maxlength="8" size="10" runat="server">
Note, on the server-side you will access it via the Value property of the input element, not with the Text property of a typical ASP.NET textbox control.
Contrary to what a lot of people think, ViewState only ever becomes a problem when people do silly things like nesting data-bound controls, in which case it can become bloated very quickly.
Not sure what you're asking regarding validation... but you still have options like this on both client and server. If you're working with an existing Web Forms project, I would stick with regular ASP.NET controls and keep it simple. This way, you can have out-of-the-box validation on both client and server.
Is it possible to get the value of the view state that ASP.NET writes in:
<input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="..." />
, before the processing is done for the page, in C#, in one of the page events, such as
OnSaveStateComplete
If so, how?
Thanks!
Simple answer - no.
You could start playing with internal methods like System.Web.UI.Control.SaveViewStateRecursive using Reflection but you have a very good chance that whatever you will build will stop working on the next .NET Framework update.
If you want to provide custom storage mechanism for ViewState you would implement PageStatePersister.
In the page directive of my page I have set EnableViewState="false". But I am still seeing some viewstate on my page source with this field
<input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="/...................................
How can I remove the view state completely. I am using .NET 4.
What you're seeing is Control State. It cannot be turned off.
try using ViewStateMode property , as you are using .net 4
ViewStateMode="Disabled"
check for these links
Viewstate controling asp.net 4.0
You can't, it's a feature of webforms. If you don't like this, use MVC instead.
I'm working on an application which generates a list of customers from a db. I have disabled ViewState in default.aspx, but now when I viewed the source code of the generated HTML page I saw that the ViewState is on.
I've tried to add both ViewStateMode="Disabled" and EnableViewState="False" (separately and even together) without any luck.
What can be wrong?
ViewState code from the source code if it helps:
<div class="aspNetHidden">
<input type="hidden" name="__EVENTTARGET" id="__EVENTTARGET" value="" />
<input type="hidden" name="__EVENTARGUMENT" id="__EVENTARGUMENT" value="" />
<input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="88luWaDvrTt0+OWLhB and a lots of characters after this...
EDIT: Now when I looked again in the source code I can see the following which I find strange:
There's A LOT of ViewState characters (takes 15-20 seconds to scroll through it)
There's two places with ViewState code, separate from each other
ASP.Net pages have both Control State and View State. Control State is for absolutely critical data that the control can't function without (at least in theory).
View State and Control State are both stored in the same field. A site with View State completely disabled may still have Control State.
Unfortunately, ASP.Net is quite inconsistent as to how it differentiates between the two. For example, a DropDownList will no longer fire change events with View State disabled. I consider that a critical function of a drop down and I would be happy to spend the few bytes of space to store the currently selected value in Control State so that a change could be detected.
If you are wondering about the contents of the hidden field containing state, you can decode it. It can be very useful for detecting View State "leaks".
Looking at the MSDN documentation, even when you disable it, it is still used to detect postbacks:
Even if EnableViewState is false, the page might contain a hidden view
state field that is used by ASP.NET to detect a postback.
You can deserialize the viewstate to see who's putting data in there:
LosFormatter lf = new LosFormatter();
object deserialized = lf.Deserialize("!!! YOUR VIEWSTATE HERE !!!");
Attach a debugger and have a look at the contents of deserialized
on the page products.aspx i created a form:
<form id="send_info_form" method="post" action="send_email.aspx">
<input type="text" name="the_name />
<input type="submit" />
</form>
when i click on submit it's forwarded to the same page (products.aspx) and not to the page i set in action attribute of the form.
It looks like you have a misunderstanding about how ASP.NET's logic works- ASP.NET has a much different paradigm than PHP or ASP does.
It seems like you're taking more of an ASP classic or PHP approach of directly handling the landing pages of forms and POST values, which you no longer have to do. You shouldn't need a separate page to handle the logic of the form submission either; this is all handled by event handlers in the submitting page's codebehind.
Instead of handling input elements directly, you should use ASP.NET's server controls to handle all the inputs for you.
What you should be doing is:
In the Products.aspx page:
E-mail Address: <asp:TextBox runat="server" ID="txtEmail" />
<asp:Button runat="server" ID="btnSubmit" OnClick="btnSubmit_Click" Text="Submit" />
Note that there's no form tag required (besides the one already provided to you when you first make the ASPX page.
Since you're working with an object-oriented language with a business objects representing all of your HTML elements with ASP.NET, you don't have to handle reading from the POST values of the form directly.
In the codebehind for Products.aspx (I'm assuming C#, so Products.aspx.cs), add a method for btnSubmit_Click:
protected void btnSubmit_Click(object sender, EventArgs e) {
string sendEmailTo = txtEmail.Text;
// insert mail sending logic here
}
In ASP.NET, the tag will by default always post itself to the same page. This allows you to handle any events in the codebehind in the ASPX page. It's not clear from your question what exactly you're trying to do. I can think of three possible scenarios:
1) You want to post back to the same page, and toggle visibility of UI elements (other panels, etc.) based on the result of the processing, or redirect the user to a second destination page once processing is complete. This is the most common scenario and the approach I recommend be taken, because it keeps all the logic regarding the processing of the form in one place.
2) You can specify a PostBackUrl to specify another (ASP.NET) page for button controls and whatnot. From there you can do the processing from elements on the first page on the second page using the PreviousPage property. See http://msdn.microsoft.com/en-us/library/ms178139.aspx for more information.
3) If you have a separate page you wish to post to that you don't control that's not ASP.NET-based (i.e., another site's form, or a PHP/ASP3.0 site you run), things get significantly more difficult. ASP.NET puts everything in one giant elements. Since tags cannot reliably be embedded within each other in HTML, you will either have to do a silent POST manually from your codebehind, or use Javascript to quietly submit an ajax request upon submission.