I want to skip the login page if there is a token in local storage, but I don't want to move the logic to App, because I want LoginPage to remain my base page.
Currently, I have this code and it works.
public LoginPage()
{
InitializeComponent();
}
protected override void OnAppearing()
{
var localStorage = new LocalStorage();
if (!string.IsNullOrEmpty(localStorage.Get("key")))
{
Navigation.PushAsync(new MainTabbedPage(true));
}
base.OnAppearing();
// some unrelated code...
}
The problem with it is that sometimes (quite often), the login page is visible for a fraction of a second, until it navigates to the MainTabbedPage. Can I put the navigation code from OnAppearing to page constructor? If yes, should I put it before or after InitializeComponent();? Note, that some time in the application, I might call PopToRootAsync() in order to return to the login page, which this time, I might want to display.
Also, please tell me if something is wrong with this approach.
Thanks in advance.
I would highly recommend creating a splash screen. That way you can have a minimum time before the next screen shows and perform tasks. While the splash screen is visible, check if the user token is valid and then proceed to displaying the login screen or whatever screen you want to display.
Please tell me if you need further help.
How can I close the current active Page in UWP development?
I want to start a new Page and close the current one, so the user cannot go back to that page.
Is there any method in UWP similar to Android's method "finish()"?
I think you should be able to do this by removing last page from back stack after navigating to a new one. Sample code in OnNavigatedTo of a new page:
protected override void OnNavigatedTo(NavigationEventArgs e)
{
base.OnNavigatedTo(e);
this.Frame.BackStack.RemoveAt(this.Frame.BackStack.Count - 1);
}
This should prevent user from going back to last page. Of course you can modifay the back stack in many ways if you need.
hi i created an app which contains three pages,
if go from MainPage to Page1 and reversely 3 to 4 times it ts working fine, but when i Navigate from Mainpage to Page 2 it is working but when i navigate back from Page 2 to Main Page it is opening MainPage after 1 second it is going back to Page2
can you please tell me the solution for this
Okay i am going to give this a wild guess seeing that you have not given code ,
on each page there is a override method you can use, onNavigatedTo.
what i will do is put an OnNavigatedTo event on each page and put a break point in that event and step to see what each individual page does, here is a quick example where i use onnavigated to test if the navigation to this page was a 'back' navigation!
protected async override void OnNavigatedTo(NavigationEventArgs e)
{
//Check if navigation was back!
// you can add the breakpoint here if you want to.
if (e.NavigationMode == NavigationMode.Back)
{
messagebox.show("Nav is back!");
}
now you can easily see what each individual page does when navigated to :) hope this helps a bit.
I'm looking for the best practice on how to pass data from page to page.
In Page A I have a button that fires off Page B.
On Page B I have 6 textboxes that allow the user to enter information.
When the user is done, the click on a button that brings them back to Page A.
I want to pass that data back to Page A.
I've seen suggestions to:
build XML documents and save to Isolated Storage
use the App class to store information in properties
pass it like a query string
I'm looking for the Best practice. Is there one that Microsoft recommends or one that is generally accepted as the best way?
Thanks
PhoneApplicationService.Current.State["yourparam"] = param
NavigationService.Navigate(new Uri("/view/Page.xaml", UriKind.Relative));
then in other page simply
var k = PhoneApplicationService.Current.State["yourparam"];
Personally I'd store the values entered on Page B in a model(object) that is also accessible to Page A.
Depending on how you're navigating to Page A the second time, one or more of the following may be usful to help understand passing values between pages:
How to pass the image value in one xaml page to another xaml page in windows phone 7?
Passing a complex object to a page while navigating in a WP7 Silverlight application
How to pass an object from a xaml page to another?
How to pass a value between Silverlight pages for WP7?
How do I navigate from one xaml page to another, and pass values?
One thing you can consider is to use MVC: let your App be the controller, store all data in the model, and the pages are just views that contains pure UI logic. In this case your pages are painters and you pass your model object around. This gives nice isolation of business logic and the UI so that you can rev them easily.
BTW, Silverlight and XAML are great tools for MVC so it's a natural match.
There's a couple of things at play here. First of all, if/when the user uses the Back button to return to page A instead of your button, is the information in the text boxes exchanged or not (is Back = Cancel, or is Back = OK?)
That said, if you're using NavigationService.GoBack (which you should be instead of NavigationService.Navigate, because if you use the Navigate call, repeated hits of the back key will cause all kinds of bad UX for your users), then QueryStrings are not an option. Because pages really have no way to reference each other in the WP7 Silverlight nav system, you need to use a 3rd party to hold your data. For that, you can turn to (a) Isolated Storage (slow & heavy, but fail-safe), (b) Use the PhoneApplicationService.State dictionary, or (c) use Global properties of some kind, either hung off of the application object, or using Statics/Singletons...
Remember to watch for Tombstoning behavior when you do this - your page will process the OnNavigatedTo method when (a) you navigate into it in your application (b) you navigate back to it when you complete your work on Page B, or (c) you tombstone your app from that page and return to your application using the Back key.
Sorry I didn't give a more direct answer there - a lot depends on your specific circumstances. In the most general case, I'd strongly consider using the App State Dictionary on the PhoneApplicationService...it is lightweight, easy to use, and survives tombstoning. Just be sure that your keys are as unique as they need to be.
If you create a new Windows Phone project and use the Windows Phone Databound Template you will have most of the work done for you.
What you will want to do is set up the ViewModel to contain all the data for your app. You can serialize and deserialize this data using IsolatedStorage so that it's saved across application sessions and when Tombstoning.
In the template you will notice MailViewModel and ItemViewModel. MainViewModel stores all the data your application needs including an ObservableCollection of ItemViewModel, and ItemViewModel represents the individual data type for your application.
On the DetailsPage.xaml page you'll want to DataBind each textbox to the App.MainViewModel Items. Set the binding to TwoWay if you want the ViewModel to get updated as soon as the user manipulates the data on DetailsPage.xaml. You can optionally set the Binding to OneWay and then have an OK button that writes the changes back to the ViewModel and saves to IsolatedStorage.
Here is an example of what a Binding looks like:
<TextBlock x:Name="ListTitle" Text="{Binding LineOne}" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/>
In this case LineOne is a property in ItemViewModel and the page gets this data from the query string when the user selects an item from the MainPage.xaml. The DataContext for the page determs where the databound information comes from.
Here is the snippet where the MainPage passes the selected item from the ViewModel to the DetailsPage.
// Handle selection changed on ListBox
private void MainListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
// If selected index is -1 (no selection) do nothing
if (MainListBox.SelectedIndex == -1)
return;
// Navigate to the new page
NavigationService.Navigate(new Uri("/DetailsPage.xaml?selectedItem=" + MainListBox.SelectedIndex, UriKind.Relative));
// Reset selected index to -1 (no selection)
MainListBox.SelectedIndex = -1;
}
Here is how the DetailsPage gets the selected item.
protected override void OnNavigatedTo(NavigationEventArgs e)
{
string selectedIndex = "";
if (NavigationContext.QueryString.TryGetValue("selectedItem", out selectedIndex))
{
int index = int.Parse(selectedIndex);
DataContext = App.ViewModel.Items[index];
}
}
Play around with the default template above and ask any additional questions.
The beauty of databinding and the ObservableCollection is that you can just update the data and the UX will reflect those changes immediatley. This is because any changes to the data fires off an event:
public string LineOne
{
get
{
return _lineOne;
}
set
{
if (value != _lineOne)
{
_lineOne = value;
NotifyPropertyChanged("LineOne");
}
}
}
NotifyPropertyChanged() that broadcasts this information to the View.
You can also keep it simple and use PhoneApplicationService.Current.State which is basically a hashtable. You will need to implement your own marshalling to and from isolated storage if you want anything to outlive the app.
Omar's suggestion to use the Windows Phone Databound Template is probably the best idea on this page. It amounts to the same as my suggestion but you will get a better result (more maintainable code) at the cost of a longer steeper learning curve.
I suggest you do it my way and then do it again Omar's way.
as i implemented like this.. Whether its correct or not i dont know..
When u click news list page it should open the news detail page.
I want to pass the selected news item contents from news List-Page to news-details Page.
the News list page contains following method.
protected override void OnNavigatedFrom(System.Windows.Navigation.NavigationEventArgs e)
{
NewsDetailsPage newsDetailPage = (e.Content as NewsDetailsPage);
if (newsDetailPage != null)
newsDetailPage.SelectedNewsItem = SelectedNewsItem; //Contains the news details
base.OnNavigatedFrom(e);
}
In the News details Page. U can access that(SelectedNewsItem) object.
This may or may not be correct.
One option is to use Application.Resources:
Store data:
Application.Current.Resources.Add("NavigationParam", customers);
NavigationService.Navigate(new Uri("/Page2.xaml", UriKind.Relative));
Retrieve data:
var customers = (List<Customer>) Application.Current.Resources["NavigationParam"];
Here's a blog post with describes this in more detail: http://mikaelkoskinen.net/windows-phone-pass-data-between-pages-application-resources/ (author: me)
I am using Silverlight to develop a Windows Phone 7 application. My requirement is when clicking on 1 image then it can be displayed in next page and zoomin that image automatically in that page. In the same way by clicking on another images same approach has to be occur. Give Detail explanation and Code For that One i'm new in windows phone application developer.
There are several ways to achieve this, but perhaps the simplest way is to use the Navigate method.
When the user clicks on your first image, grab the "id" of that image (or url, or whatever you need to pass to the second page), and add it to the navigation string like this:
NavigationService.Navigate(
new Uri(string.Format("/MyNewPage.xaml?image={0}",myImageID), UriKind.Relative));
Then on the destination page, you can extract that item from the navigation string in the OnNavigatedTo handler:
protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
{
myImageID = int.Parse(NavigationContext.QueryString["imageID"]);
}
Like I say, this is a very simplistic approach, and you can implement something much nicer with databinding, but it will do the trick.