I have a dropdown element directive to display in essence a styled dropdown list with additional capabilities.
My dropdown controller has a function called openDropdownItems that get's executed when the list should be displayed.
Then I also have another attribute directive called setInViewWhen that provides an expression when the element should be scrolled into view when condition is true.
<x set-in-view-when="something.item === selectedItem">
This is just an example of some X element with my attribute directive applied.
The thing is that I would like my dropdown list items (LIs namely) to have this directive on them so when user navigates over them using a keyboard, it would automatically scroll them in view when they get passed visible viewport. Whether these items are displayed within a scrollable container or as a whole in a list longer than the browser viewport isn't really relevant.
The main idea is for scrolling to follow dropdown list selection. Whether that should scroll the main window.
The problem
I can make my setInViewWhen directive completely independent but that means that I would have to search for the closest scrollable container whenever condition changes on an item. This seems to be quite a bit of processing that I would like to avoid to repeat (I need to traverse the DOM upwards, checking each node's calculated stylesheet property OverflowY + some additional checks.
This basically seems redundant because whenever I get the closest scrolling ancestor all sibling elements with the same directive could reuse the calculation result.
Question 1
How can I share this knowledge between sibling directives? If I was to fire an event I could not know whether receivers are siblings or not without any additional processing.
Question 2
Instead of checking for scrollable container every time when my directive's condition becomes true I could theoretically change dropdown parent's openDropdownItems to first complete it's original execution an then also execute the scrollability check and use the result of it along with my directive's condition.
I can gain access to dropdown's controller in my directive via directive requires property and adjust it in the post-link phase.
But this also means that I couldn't use my directive outside of dropdown which I would like to as it is a generally usable directive I could attach on several elements in my app to scroll elements into view under certain conditions.
What would you suggest how to do this?
To sum up the comments:
For Question 1, there is no direct way for sibling directives to communicate with each other. I usually create a wrapper parent directive to relay the messages.
As per the comments, the condition something.item === selectedItem introduces a watch; for a list of select items this can be many watches and detrimental to performance. Even if it doesn't occur now, it is a trap and someone may be lured into using this for a long list of items in the future. I would rather have a single watch in the parent of the <li>s and add the "scroll into view" logic there.
With the previous point in mind, you could still have a standalone setInViewWhen directive (seems useful) and have the controller of your X-select replacement directive share code with it. E.g.:
a service containing the common functionality,
an angular value containing a base class (Typescript or JS) and have the controller of both the setInViewWhen and X directives extend from it
or any other solution that is convenient for your case
Related to Question 2: The children could require their parent and change a method in it (this technique is even endorsed by Angular, see ng-model and custom controls where they override ngModel.$render() by replacing it). If you do that however, there would be many children changing the method of the parent, which could lead to a mess.
Related
lately I have a pretty significant problem with ng-view and ng-if.Suppose there is a dropdown with two elements (element one and element two).The two elements change a property on rootScope.
I have two more items at another location (div-container, container one and two containers). These are displayed by ng-show - container one at element one and container at element two.
As soon as I click the one element one time and the property of the rootScope changes and then I reload the page, the two containers are alternately displayed without that I do something.
I have several watchers, seveleral ng-cloaks and use the routing using ng-view. I would also like to mention that the application is relatively large. Most often, the problem occurs on Android, presumably on iOS.
As soon as I click the one element one time and the property of the
rootScope changes and then I reload the page, the two containers are
alternately displayed without that I do something.
Did you mean the other two containers just show up for a second and then disappear? If that is the case then I think the condition you are providing inside ng-show is true at the loading time so they appear for a while before the condition changes and then they disappear.
You have to make sure the condition for ng-show is initially false.
I'm trying to accomplish something that seems easy at first glance, but ends up being quite the challenge. I have an accordion-like section of an app, where each accordion item should open a child state when activated, with a few extra requirements:
child states can (and should) be the same child state, with different parameters.
child states are not know up-front, they're loaded dynamically.
deeplinking to a child state should work as expected. The accordion item expanded and the proper content loaded.
The idea is easy, there should be one child state, which loads/shows different data depending on the passed parameter, but the template of that child state should be place in the activated accordion item, not in one fixed place.
I partially tried the multiple named views option from ui-router, but doesn't look promising, since it would actually load all those named views at the same time. Plus, I need them to by dynamic, and even though is possible to define states dynamically with for example with Future states, it doesn't seem to be the right choice here.
Right now, I can only see 2 options:
Re-parent the ui-view inside the desired accordion item (didn't work at first try but did if I re-parent the container of the ui-view) but has buggy side-effects right after the testing, and I fear some critical side effect later. Basically the parent controller get's reloaded for a second time, keeping the previous instance in memory. Plus i've seen some duplicated DOM content in places outside the scope of even the parent. I don't like this approach of course, but has the advantage of actually placing the content I need inside the container I need.
Leave the ui-view outside the accordion, position absolute-it, and manage it's position based on the current state when navigating. The position absolute is not a big deal, but I need to keep measuring the content's height, and dynamically set the height of the expanded accordion item to make it look like it's inside of it :S. To make things more difficult, I'll probably have to place some complex rules to position this correctly for the responsive design this needs.
In the end, it's a route/code hack vs a visual hack. I'm taking the visual hack since it sounds safer, but it's definitely going to be more work. Any other approach or comments will be highly appreciated.
-- Edit --
There's a better option at least for the 2 options I had in mind: create the different child states (1 child state, with params) but not associate it with a template. Just leave all the DOM in the parent state/view, and manage visibility with ng-if
Did you think about the option to use only one child state for all this and pass the additional information you need using parameters of the state?
so have URL-paramter for the accordion-section-id you want to open and other parameters for the different data to show.
Then open the correct accordion-section based on the stateParamter. Write a directive with private scope to render the content of the section and in each accordion reuse the same directive and pass it the correct data.
Then if the user clicks to open another accordion section, instead of the normal 'open'-action use a $state.go('myState, {accordion-id: 'newidtoopen', datatoShow: dataids}).
I'm stuck with Angular. I have a directive that shows a list and when the user hovers over an item, I want to show a preview of the item, with the preview being given by the directive user.
Some tricks though... I want the user to be able to filter the list using an input [which is easy on it's own] and there is some basic styling surrounding the list that I would like the directive to handle, like adding the checkboxes that well be watched to create the model for the directive.
I want the directive user to simply be able to write:
<preview-list list='unfilteredlist'>
<div>
<h1><blink>{{title}}</blink></h1>
<h2><marquee>{{html extrodinaire}}</marquee></h2>
</div>
</preview-list>
I tried using ng-transclude, but it uses a sibling scope and I've been looking for work arounds and I can't find any. The only ones I found involved writing the entire template in javascript, which honestly I can't believe people think that's an acceptable solution.
Any solutions, or is this actually completely impossible in Angular?
As i see it you have two options :
Create a preview box for each member in your list and toggle visibility on hover. This is great if you have only a few values and the preview box is heavy.
Create a transcluded directive in which - the main scope will hold the list and the currently hover element. The sibling scope will hold the preview container. Once the selected value changes the preview box will update (according to your bindings) and only thing left to do is position it.
transclude is hard at first but it pays off.
Hope this helps.
I am using a directive "slideable" which creates a slideout area and has a toggle. This code that was not written by me but it demonstrates a larger issue for me. When I changing views (most commonly /user/:id type), slideable is a directive used on the template. The directive searches for an element during its link function and binds a click event. The issue is that when I am changing routes and the new view ( same type but different id ) is being loaded the directive is re-binding to the old view. If I stop the browser in chrome during the link then I will see two ng-views on the dom and the issue is it binds to the one that is leaving.
I also have other issues that appear to be related to this phenomenon. Is it normal that the old view would still be on the dom while the new view is being formulated?? Why wouldnt the old-view be destroyed before the new one is rendered? How do I get around this issue in a directive like this?
Thanks.
I am looking to understand conceptually what is happening. I already modified the directive to select the latest view and to appropriately search and bind to the correct element. But I am a bit perplexed as to why there would be a state where both co-exist on the dom.
One definitive reason why the old HTML fragment is briefly present along with the new one is to support animation of transitions from the old to the new. Take a look at the ngView documentation and you'll see an example of an animated transition, and it'll be clear that this is not a bug or a design flaw.
Usually when someone has problems with binding to the right element or element's event, it's because they are selecting the element without limiting the scope of the selector to the HTML fragment being added or updated, or trying to target parts of the DOM outside of the directive. So that's the first place to check, that the directive is doing things right, but like I said we'll need code to check on that.
I need to build a dialog to be used with any item on a list of items. The dialog is pretty much the same regardless of the item except for the values of the fields which are obviously item dependent.
The directive I am building is reading the template from a file, compiles it with $compile and then binds (links) it to the scope of the item. The result of the binding is a DOM tree. To make the dialog visible I need to append this tree to some element in the existing DOM. The nature of my dialog is such that it makes sense to append it directly to the body tag. The dialog will be used many times in combination with different items on the list
So here is my question: How much of this process (compile, bind, append) can be done in advance? I certainly can run compile once. I can also bind the compilation result to the $rootscope and append (hidden) it to the body tag. This way I can later just turn on visibility and show the dialog.
But if it is already bound and attached to DOM, is it kosher to re-bind it to some other scope, if so - what's the right way to do it? Another question is is it even worth it? might be just re-insert it every time it is needed?
If you're only ever going to display one dialog like that at a time and you will use it frequently, you don't have to re-bind it to another scope, just change the data on the scope. Something like this:
Create a service for your dialog
Create the directive and inject your service into it. When the linking function executes, pass something like $scope.dialogData to the service so that the service can update the data.
Create a controller that gets the service injected. Set the dialog data through the service to display the dialog. Since you're modifying data in your controller that's on the directives scope, Angular notices that and updates your dialog.
Add ng-show on your dialogs wrapper to make it simple to implement open()/close() methods on your service.
Now you have a dialog that can be used from anywhere in your system, and you're just re-using the same directive without having to mess with the DOM or compilation.
This is indeed excellent question and I'm happy to see that more and more people are starting to approach dialogs as services.
Regarding your particular questions, here are some of my thoughts:
You can "cache" linking function (that is - function that is returned from the $compile call) and then call this function as needed (passing in scope variables).
Instead of inserting (hidden) compiled element you could only attach it on demand, when a dialog gets opened. On top of this I would rather attach modal element to the $rootElement instead of <body> just not to touch DOM elements above where ng-app was defined. Just not to touch parts of the DOM that AngularJS is not controlling.
IMO dialogs are really close to AngularJS routes (as they provide different "views") and as such it would be very nice to have ability to resolve promises before modal is shown (as with routes).
In fact there are number of things to consider when designing a good, generic dialog service and I hope that those advice, alongside with excellent input provided by others, will get you started. But this all is a bit theoretical so if you are looking at the implementation of what was discussed here you can have a look at this implementation. ($dialog service from http://angular-ui.github.com/bootstrap/ - it is fully customizable so can be used with CSS other than Bootstrap's. Documentation here).
It can be seen in action in this plunk: http://plnkr.co/edit/PG0iHG?p=preview
Excellent question I think. You're wondering if one can "hot swap" the scope of an element. I don't know if there's a way to do that, or even if there is, if that's the Angular way. I take it you looked at how ng-view works to get as far as you've gotten?
My advice is to do the $compile once, keep the result, the link or transclusion function or whatever it's called in Angular parlance, around somewhere. And call it for each needed instance of the dialog.