I would like to know how to go about accomplishing state restoration in an application that uses a UIPageViewController. Given that, at the time of termination, the controller is displaying page n of N and page n has state that is the result of user interactions: How would one go about employing iOS's state restoration mechanisms to save and restore page n?
I have created an exploratory project on github. This project was created via Xcode's Page Based App project template. I have updated it by adding the properties and overrides required to bring state restoration into play. As it currently stands the RootViewController saves the current DataViewController's data (i.e. the month) and restores it upon relaunch. What I would like to achieve is to arrange things such that iOS is invoking the current DataViewController's encodeRestorableState and decodeRestorableState methods.
State restoration occurs in two phases: 1) iOS recreates the view controller hierarchy, and 2) iOS restores the state of each of the view controllers. It is phase 1 wherein I am experiencing the most confusion. In the case of the Page Based App it is the RootViewController's viewDidLoad method that creates the PageViewController. If iOS were to recreate the PageViewController then how would the RootViewController obtain a reference to it? Similar questions apply to iOS's recreation of the DataViewController.
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I have a tab in my Ionic project which consists of a map. On that map, the user can pan around and do things such as draw polygons, etc.
However, when the user moves to another tab and comes back, the map is completely reset and all his work is gone, because Angular seems to destroy the state. In addition, another request will have to be made to the map tile server because of this, which can be expensive (financially) for the company.
Is there a way to tell Angular not to reset the state when navigating from tab to tab? Or perhaps this project isn't a good fit for Angular based technologies?
I am not sure how the map is being created in your scenario, but have you tried nesting your states? http://angular-ui.github.io/ui-router/ has a great example of a nested state that shares data between them. You might also look into the $cacheFactory service: https://docs.angularjs.org/api/ng/service/$cacheFactory and use it to store and retrieve your map.
Well, as technology progresses, issues we solved long ago crop up again.
Back in the dark ages, when PHP and ASP were considered awesome, we always had a problem with view states. If you had a page with say a dozen select combo boxes on it, your user chooses some combination and hits next, then realizes they screwed up and hit the back button on the browser, the combo boxes would be back in the default state, usually with option[0] selected. In order to prevent this, we had to write boatloads of boilerplate code that would save the state of those combo boxes to a cookie, or session variable, or something so that when the user hits the back button, we can reload the combo boxes back to the state they were in when they left.
This problem was compounded even further if you had a datagrid on the screen. Because then you would have to come up with some slick way of saving that grid somewhere to prevent from having to hit the database again.
Then came the light. Browser developers realized that most web developers were on the verge of going back to writing terminal programs in Cobol due to this issue and added UI caching to the browsers. This allowed us webdevs to not have to worry about this anymore except in odd situations.
So, life was good. Then someone came up with the bright idea of trying to replicate GWT without all the hassle and the web explodes with all these javascript frameworks. The one im dealing with specifically at the moment is AngularJS 1.2.10 with Angular-UI. I have until Friday (most likely wednesday tho) to make an initial assessment on if this technology is a viable alternative to our current standard (thats pretty much universally hated) JSF.
So, i follow some guides, pound my head against the desk a few times, and I have an angular app with 3 actual HTML pages, each HTML page with 2 views.
Before you go there, understand we can't use it unless we can do multi-page JS apps. Some of the applications that this will be worked into have been in development for a decade or more and its simply not financially practical to scrap an the entire UI and start over again. We would instead be doing things like taking these 50 struts pages and converting them to angular/rest and linking them seamlessly back into the remaining 800 struts pages of the application.
So in my exercise of playing with this, I encounter my old nemesis. Back button view state issues.
I have been playing with the UI-route system. The fact that I can deep link using the route system solves part of my problems. But, if say I have a search page like this:
view-search
combo: search type [member,nonmember]
combo: result type [detail,summary]
combo: search state {all the states]
textbox: contract number
etc etc etc
And various combinations of combo box selections and text entries comes up with a list of 1000 people. Now the user selects one of those people on the data grid and it takes you to view-detail. Well the fact that you can use routing to do something like index.html#detail/bob is cool, but if the user realizes thats the wrong bob and hits the back button, they get a blank search screen again and they have to enter everything over and worse yet, send another search to the database to rebuild the datagrid. Some of these screens have 50 or more options to choose from when searching for data so trying to put all of them into the URL routing sounds completely impractical to me.
Now in my research I found this post:
Preserve state with Angular UI-Router
And that has promise mainly because I have a view state object that I can store into a Redis database or a session EJB for cases when the user actually jumps out of angular and into the legacy Struts application, then back buttons back into the angular application, but the fact still remains that on some of these pages, that is a huge amount of boilerplate code that we would have to write in order to make it work.
I don't really mind the idea of having to manually save off the view state object and read it back in from a Redis server or something anytime a user enters or leaves an HTML page in the system. What i'm really looking for is a way to automatically generate the object that is to be saved without having to write volumes of boiler code.
Is this possible? I keep reading the ui-route documentation but it doesn't look like this is addressed, at least not that i've translated yet.
If this is possible, what controls should I be looking at?
thanks
-------------- Edit
I just thought of something. There is one central scope to each of the single page applications. (Im basically going to be building a multiple single page apps and hooking them together) So if i use a naming convention, something like this
$scope.viewstate.view-search.searchType
$scope.viewstate.view-search.resultType
$scope.viewstate.view-search.searchState
Then the viewstate object should simply be a js array and when I create a function to move to struts.do, i can simply save that array off to the Redis server as a nested map object. Then when my user back buttons back into the angular app, i can capture that using the route system and retrieve that viewstate object from Redis and insert it back into my scope, thereby rebuilding the scope for the entire single page app in one shot.
Would that work?
I believe that you have a very complicated issue of trying to keep the view states between your varying pages with the amount of data in your pages. I think that the only real effective way to do this is to write an angular service that you can then pass to your various pages. as You already know the service is a singleton that you can use in various controllers and could be utilized to maintain the view state as you described. here take a look that this link and see if it will help: http://txt.fliglio.com/2013/05/angularjs-state-management-with-ui-router/
After some thought what you suggest in your edit might work, but I would still use a service to retrieve that array of data, as it would make it easier to reinsert in to angular scope
I am exploring something similar for an Angular app that I am writing. Keeping a user login during a page refresh is easy. Displaying the state on the page after a refresh is an entirely different problem.
How long must the state be persisted? I'm evaluating two possibilities.
First, saving the state (current form values or whatever) to the database. As the page changes, incrementally save the state to the database. On a browser refresh check the database for saved values.
Second is to use local browser storage. This is 5 megs of storage. 5 megs is a lot of text. Again this data would incrementally be saved into storage. When the browser refreshed, simply load data from localStorage.
I have a nontrivial Angular SPA that uses ui-router to manage multiple views, many of which are visible at the same time. I need models to be visible across controllers, so I have services written that allow me to have controllers pull down fresh copies of model data that has been updated.
I apologize in advance for the length of the question, but I will state the problem then state what I have done to address issues I'm sure others in the Angular community have struggled with.
I believe my problem is not understanding the lifecycle of controllers / views, because I get behavior where a controller initializes correctly the first time I go there, but then seems to never run again, even when I navigate to it using something like $state.go("state name").
In one view (contrived example), I show a summary of information about a customer, and in another view I allow a user to update that customer's more detailed profile. I want a user to edit, say, the customer last name in the detailed view, and have the summary view automatically recognize the change and display it.
I have a fiddle that shows 3 views and a simple password changing Service. The flow goes like this:
You can see each view gets initialized and displays the initial password retrieved from the service. All views are in sync with the DataService.
The middle view allows you to enter a new password and change the one stored in the service. Console logging confirms that the service picks up the new password just like you would expect.
(odd behavior #1) When the DataService receives the new password, I would expect the other 2 views (top and bottom) to display the new one. They don't... they still display the initial password.
There is a button to allow a user to go to another state via $state.go("state name") (a child state of the original) which also retrieves the password and displays it. This works the first time (see #5). Now the top view shows the outdated password, the middle view shows the new one, and the bottom one shows the new one as well. This seems normal, since the new view is invoked after the DataService contains a new password value.
(odd behavior #2) If I click back in the middle view and change the password again, and click the button to change states again, the bottom view (which updated just fine in step #4) no longer updates its copy of the password. Now all 3 views show different passwords, even though I am using a single service to pass values between controllers as suggested pretty much everywhere you look for Angular best practices.
Some possible solutions:
Tim Kindberg has an excellent slideshow here that seems to recommend using ui-router's state heirarchy to "pass" data among views that need to pick up values from other views. For a smaller-scale app I think I would settle on this, but I expect our application to have 30+ views displaying data from over 100 REST endpoints. I don't feel comfortable maintaining an application where all the data is being shared by a complex inheiritance tree. Especially using a routing framework that is at version 0.2.8.
I can use events to have controllers listen for changes in the data model. This actually works well. To accommodate performance concerns, I am using $rootScope.emit() and a $scope.$onRootScope('event name') decorator I found on here. With this approach I am less concerned about event performance than I am about wiring this huge app with a bunch of event listeners tying everything together. There is a question about the wisdom of wiring a large app using angular events here.
Using $watch on the value in the DataService? I have not tried this but I am hesitant to hinge an app this size on hundreds of $watches for performances reasons.
A third-party library like bacon.js (or any of a dozen others) that may simplify the event spaghetti, or create observable models that my controllers can watch without the risk of $digestageddon. Of course, if there is a concise way to handle my issue using Angular, I'd prefer not to muddy the app with 3rd party dependencies.
Something that lets controllers actually reference .service modules by reference, so I don't have to depend on tons of event wiring, complex state hierarchies, 3rd party libraries, or seeding the app with hundreds of $watches and then kicking off $digests to update controllers' references to Angular services?
Some solution that relies on time-tested OO and design patterns and not a 3rd-party library or framework that has a version that starts with 0.*.
Thanks in advance... I appreciate the help!
This is no problem of ui.router. If you intend for your model (your data service) to be a single source of truth, you have to refrain from destroying it.. err.. the reference to it that is. And in your case, assigning a primitve (a string) directly to the scope, instead of a reference to it. In other words...
var password = {pw:'initial value'};
and then later setting/binding only on
password.pw = newpassword
{{password.pw}}
Heres a fiddle. And also here is a short little read on scopes, It also includes a video of an angular meetup where Misko talks about "always have(ing) a dot in your model" link and how the $scope is a place to expose your model, not be your model. (aka not a place to assign primitives like password = 'initial value')
Hope this helps!
try remove the animation property of your ion nav view.
remove the property
animation="slide-left-right"
it would be ok.
I am currently working on a large enterprise web platform which loads different web applications (html/js/silverlight) as views so it is almost like a container or a framework for accessing different types of web applications.
We are currently reviewing the migration to Angular however there's one problem (at least) which we can't address.
in the current non-Angular version when a user loads Application-A from within the framework and let's say types "ABC" in a text box then he decides to navigate away and load Application-B and after using that application when navigates back to Application-A he can still see "ABC" in the textbox in other words he has "Persistent Workspace" so every app that he loads whether it be Silverlight or Html/JS has the ability to be kept loaded into the memory.
Regardless of the right or wrong of this approach can anyone think of the way this can be implemented in Angular? a simple overview is enough.
[UPDATE]
Please note that we are dealing with iFrames for each of the web apps we currently load, so there's no model that we can persist to the browser storage or elsewhere. if all our apps where html/js based then we would have no problems as we could serialize the state of each view but since some are in Silverllight we can't do that. hope this clarifies.
Thank you all.
You can always synchronize Angular's state with the local storage of the browser. So there will have to be a unique key for every field in every form and use something like this.
Alternatively, you can listen for the $routeChangeStart event (docs) from within each controller that cares to save status. Then the controller can decide to serialize its state (or not) to the local storage. On controller initialization, the saved state must be retrieved.
Solutions involving the browser's local storage will not affect the server but will not be available to the user when he/she uses another computer. Otherwise, you should listen to the route events as before, but synchronize the "persistent workspace" with the server (slower, more development time).
I have a web application with require.js, backbone.js and jquery.
The brief structure of the app is as follows:
There are 2 sections on the screen (toolbar and main content below).
There are multiple components (address management, event management), each triggered by a hash fragment change and require a
page transition.
There is one backbone.js router. It's the heart of the application. The router is activated with a new hash fragment (manually entered,
back button, menu item selection).
Up until now, in the router, I made the page transition, I DIRECTLY called the controller ("view" in backbone) of the selected component.
So there's a CENTRAL handling of controller calling.
But this has to change now to a DISTRIBUTED handling. I now need to respond to a new hash fragment from two different places: From the toolbar component and from router.
So my idea is to exchange the direct controller calling mechanism with pub sub. Now MULTIPLE components could register for a special action and the router just "fires the event".
I searched around and found Chaplin (https://github.com/moviepilot/chaplin), a backbone.js example application.
The developers of Chaplin seem to have a similiar thing called "ApplicationView" (https://github.com/moviepilot/chaplin#toc-router-and-route):
"Between the router and the controllers, there’s the ApplicationView as
a dispatcher."
Is there anyone who has already this kind of architecture and can tell me his experience with this or has anybody solved this in another way?
I've used a similar, though maybe less complex, architecture in this project. I give a pretty good explanation in this answer to a related question. The quick overview:
I manage app-wide events that change the application state using a singleton State model that works similarly to Chaplin's pub/sub architecture. This is just a basic Backbone model, with some added methods to deal with serializing and deserializing attributes as strings, so they can be set in the URL.
Application components that change the application state in response to user interaction or other input do so by setting properties on app.state.
Components that need to update when the application state changes do so by binding to change events on app.state (it looks like this is exactly the way Chaplin's mediator works, though they renamed the methods to fit the pub/sub paradigm).
I treat my routers like specialized views that update the address bar and respond to user input in that area. Changing the address (manually or by clicking on a link) causes the router to set() the necessary changes on the app.state model, and everything else updates accordingly.
I hope that's helpful - I think it's a little simpler than the Chaplin approach.