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 Now the top view shows the outdated password, the middle view shows the new one, and the bottom one shows the new one as well.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.
Related
I am using UI-Router and multiple nested named views. One of my pages, Company, has a sub section concerning Jobs. Jobs need to know the active Company, as well as access to a slew of other services that aren't really part of Company.
The straight forward approach is to throw everything into Company and inject all needed services there, but I'd like to separate and keep the Job sub section in its own view. My issue is here the Company page allows for navigation across multiple Companies, and I don't know a clean way to inform the Job view of the active Company change. Right now I am using a rootScope Broadcast, and it's really dirty and looks like it'll cause me issues down the road.
How can I notify a child view that the parent's data has changed, and pass along an updated parameter at that time?
I ended up using a $broadcast from the parent and $scope.on from the child, working pretty well.
Im trying to share data between 2 views. I need to use the 2 views at the same time on two different machines. One is controlling the other(ex: a counter) 1st view has next(+1) and the other just displays the result. I want the data to synchronized/binded. I do not want to have to refresh the 2nd page or to have to pull data with a timer or otherwise.
My idea was to use ng-view and routeProvider, I know that when the view changes the scope is cleared so I tried to use a parent controller/scope, the data is shared but I have to refresh the page on my 2nd view. I tried a service, same thing. I tried to $watch the result of the service but on the second controller/view no event is picked up so the view doesn't update.
what is the way to go? I was thinking about broadcasting or emit a custom event and trying to catch it, will that work? Am I just not binding to the service correctly? Would ui-router work better? I feel there should be an easy way to do this.... Im not seeing it! Please help if you can.
One of the simplest (in my opinion) implementations of client-client communication is using WebSockets. While that does have compatibility limitations (some browsers), that can easily be overcome by using a library like socket.io. Also, it's easy to write an Angular wrapper/service over socket.io that can be shared across components of your app, or even different modules.
It's also pretty simple to write a Node backend with socket.io
This might be a good read.
I would suggest you to focus on pushing stream rather than sharing it. Some how you need to push stream to second view which is changes in first view.
You may want to check this
Is there some way to PUSH data from web server to browser?
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'm working on a really big project. The aspect I'm currently working on requires that email templates are sent to a user when they're added to a learning course by another user.
The controller that deals with the request, does a bunch of str_replace tasks to find variables in the text (which the user can edit before adding another user to the learning course) and then replaces it with some values in the DB.
I took over this project and I'm not happy with the way half the things are done but time costs dictate I rather just go along with it.
The email is sent using Cake's native email function. It uses a template to capture data and send to the user.
Here's the question:
Should I keep the logic in the controller or do you think it's safe to move it to the element view's .ctp file?
My first instinct is to leave it in the controller as per the usual MVC separation ideals.
Cheers
This is a very important question - what are you using exactly for the email? The old email component or the new CakeEmail class? Which CakePHP core version are you using?
Here are some plausible aproaches here. You can:
Set all those variables, pass them to the view and do all the "replacing" there.
Encapsulate this logic in a component, attach it to your controller(s) and use it.
Just leave it in a private function within the controller and call that function whenever needed. (not really MVC)
[EDIT]
Similar question to Complex nesting of partials and templates
As of now, is it better to use Angular-UI state solution or should I stick with ng-includes ?
So far I had one view per URL in my AngularJS application. I need to build a new view, which should have 3 tabs and I'm having troubles trying to figure out how I'm going to design the view - architecture-wise that is.
Note that the business model object behind these 3 tabs is the same one.
The first tab is for viewing and editing data on the business object. So that's already two 'views' within the first tab.
The second tab is for viewing a paged-table showing data from a child collection of the business object.
The third tab does the same thing as the second one but for another child collection.
Obviously, I do not want to load the entire business object at once. I'll load the collections only if the user navigates to the 2nd or 3rd tabs.
My main concern right now is how am I going to organize the views ? AngularJS has this limitation of only 1-view per page.
Also, I need to handle browser history, so the URL must change when a tab is selected, but I should have to reload any data (i.e I must not reload the controller).
Any tips would be much appreciated.
For the record, I ended up using ui-router and its state management, which is awesome. It took me a bit of time to understand the concepts and to put that in practice, but I managed to build a pretty complex set of layouts effortlessly !