Let's say that in an ASP.NET .aspx page I have the Page Load method and another method for a button click event.
In the Page Load method I'm checking if the user is logged in by checking the Session. Whether he is or not, I'm storing the result in a Global Variable.
Boolean isGuest = false;
protected void Page_Load(object sender, EventArgs e) {
if(Session["id"]==null)
isGuest = true;
else
isGuest = false;
}
Let's say 20 minutes have passed, and I don't know if the Session has terminated or not, and then I click a Button, the event goes like this:
protected void Button_Click(object sender, EventArgs e) {
if(isGuest==false)
//do something
else
// do another thing
}
My Question is : When I'm clicking the button, does ASP.NET go through the Page_Load method again (check isGuest again) or it simply executes what's inside the Button_Click method, means, it uses a Boolean isGuest that could be false, but in reality the session is terminated, means it should be true.
Page_Load is triggered always before the control events.
Have a look: ASP.NET Page Life Cycle Overview
Side-note: If you want to do things only on the first load and not on every postback you have to check the IsPostBack property.
You can:
Define your own class with the UserID, and other profile properties;
Add that class to session in the global.asax session started event Session["NameReferingToYourClass"] = new YourClass();
Set a member variable to your session object early in the page life cycle mYourClass = Session["NameReferingToYourClass"] casted if you need to;
Then you can make any changes to your class anywhere in the code your member variable is available;
Save back your class with all the changes into session on the Page.Unload(..){ Session["NameReferingToYourClass"] = mYourClass.
This way you are using your class properties in your code, including UserId, pretty much like a windows application, there will be no mentioning of session anywhere else in your code.
Related
I have global.asax file, and I use this two functions to update cache value every 15 seconds by this code:
protected void Application_Start(object sender,EventArgs e)
{
Context.Cache.Insert("value","some value",null,DateTime.Now.AddSeconds(15),Cache.NoSlidingExpiration,CacheItemProirirt.Default,new CacheItemRemovedCallback(updating));
}
private void updating(string key,object value,CacheItemRemoveReason reason)
{
Context.Cache.Insert("value","updated value",null,DateTime.Now.AddSeconds(15),Cache.NoSlidingExpiration,CacheItemProirirt.Default,new CacheItemRemovedCallback(updating));
}
but it give me an NullReferenceException, and the context is null, please why I can't use context at the "updating" function?
Application_Start doesn't have any context.
The first event that does is Begin_Request.
Application_Start occurs when the particular website gets fired up for the first time, or after been recycled.
To keep the cache item renewed I suggest you do that in the Begin_Request, where you check if it's there, and if not, initiate it again.
This way it's only use memory while the site is being hit, otherwise not.
I have asp.net page which loads the user controls at run time I want to capture the save/cancel event of page on the user control.
User control will be load at run time so, for further development I don't want to change my code on page level.
Any help.
I solve it, with the help of observer pattern but with some more modification because my challenge is Page don't know which user control will be load on run-time in its place holder.
I create change-manager which holds the Observers references with their intended types(submit,cancel,viewonly)
Page holds the reference of change-manager and call the notify of change manager with (eventtype(enum),response(this.response object)) then change manager calls the update method In this method call Observers, kept in the dictionary of change-manager.
Iterate the dictionary and call their updates according to their interested event types.
Now I am free to remember the user-control reference of any type of casting.
see below example of get user control from page you need to use public modifier
///user control code see event is public
public void btn1_Click(object sender, EventArgs e)
{
///do you stuff
}
/// page code
protected void Page_Load(object sender, EventArgs e)
{
uc1.btn1_Click(sender,e);
}
In my application, I have a form that users fill out, then gets approved by a manager. I have various types of forms that all use the same process, so the approval buttons are all done via a user control (which includes the functionality to update the data in the database and call the postback).
However, once I click on the "Approve" button (which is in the user control), the form information doesn't update (it still says "unapproved"). A postback is definitely happening, but not sure why the page isn't updating properly.
I can confirm that the change are being made - when I manually reload the page, it gets updated - but not on the post back.
What am I missing here?
My page:
protected void Page_Load(object sender, EventArgs e)
{
int ID;
// ensure that there's an ID set in the query string
if (Int32.TryParse(Request.QueryString["ID"], out ID))
PopulatePage(ID);
else
Response.Redirect("~/Default.aspx");
}
}
protected void PopulatePage(int ID)
{
using (WOLinqClassesDataContext db = new WOLinqClassesDataContext())
{
lblStatus.Text = wo.Workorder.status;
....
}
}
I think that the Page_Load happens before the code in the submit button. To check this just use a couple of breakpoints. So the page loads the old data since the new data are not saved yet.
You should call a method to load the data inside the OnClick method of the Approve button.
After you've submitted the changes to the database, try running db.Refresh(RefreshMode.OverwriteCurrentValues) to force the changes to be reloaded into the data context.
I have a site with multiple pages, not necessarily heirarchical. I want to query the user's identity (using AD...) whenever the user first enters the site, and create session state variables for the convenience of other pages as needed. A user could possibly enter the site without going through the default.aspx page, so I thought I'd put the code in the Master Page's code-behind.
On the assumption this is a good idea, versus some sort of static class that maintains this information, I started setting it up, but found the Master Page code-behind doesn't always seem to get fired when I enter the site. Is this a debugging phenomenon, or am I right, and the Master Page is the wrong place to put this code...?
I would recommend using the Global.asax class. You'll need to add it to your web app if it's not already there. Once you have it, you can then use the various events (session start and end, app start and end and error) to implement business logic particular to what you need exactly.
I tend to monkey around with the logged in user in the Application_PreRequestHandlerExecute event of the global.asax. This will allow you to look at the User Principle (eg - User.Identity.Name) to see who is logged in (or if they're not logged in) and do what you need to (such as set Session information for the user, etc.).
Here's a tidbit of code I've got on one .NET web app that uses the Global.asax for storing user data in the Session.
protected void Application_PreRequestHandlerExecute(Object sender, EventArgs e) {
if (Context.Handler is IRequiresSessionState || Context.Handler is IReadOnlySessionState) {
SetUserItem();
}
}
private void SetUserItem() {
if (Session["UserItem"] == null)
Server.Execute("~/SetSessionUserObj.aspx", true);
}
... and then the SetSessionUserObj.aspx.cs
protected void Page_Load(object sender, EventArgs e) {
string ID = User.Identity.Name;
MyUser myUser = new MyUser();
UserItem userItem = myUser.GetUserItemByID(ID);
if (userItem != null) {
Session["UserItem"] = userItem;
}
}
This is just one manner that you can go about accessing a user's identity in the global.asax. You don't necessarily have to go about doing a Server.Execute to set user data (I just did it for other reasons that fall outside the scope of this question).
Good luck.
I have implement GridView Row Editing feature in my .net application using <asp:CommandField.
I clicked on Update button to save the record after editing the row.Now if i refresh the page or press F5 GridView_RowCommand fired again.
How can we avoid this.Is there any mechanism to identify when user press F5 OR refresh the page.Is there any method in client side or in server side.
Not exactly the best "technical" solution to your problem but you could always just do a Response.Redirect(Request.RawUrl) once you have finished doing anything you need to do in your RowCommand
Like I said, it's not the best "technical" solution but it is a solution
Dave
One method of capturing this is to maintain a session variable that is related to the page in question. In the session variable you would keep some kind of state enumeration, key or string that would determine the last action taken. You could even use a simple incremented counter, and if you ever received a postedback counter that was equal to the session variable it would indicate a page refresh rather than a new action.
Session["LastInsertedItem"] = null;
MyCustomObjType myCustomObject;
protected void Page_Load(object sender, EventArgs e)
{
myCustomObject = Session["LastInsertedItem"] as MyCustomObjType;
}
void GridView_RowCommand(Object sender, GridViewCommandEventArgs e)
{
If(myCustomObject == null || //!(compare your value with myCustomObject.field) )
{
// do your operations and save the values to myCustomObject and save that object back to Session.
}
else
{
// It is refreshed or same data is being insterted - don't know if second option is possible in your case.
}
}