In Data Down, Actions Up approach, what is the best way to scroll to a child component.
I have a collection of pages
{{#each pages as |page|}}
{{single-page model=page}}
{{/each}}
and I want to scrollTo a specific page number.
It would probably be a parent component that wraps what you have now, and looks something like this.
{{scrollable-pages pages=pages activePage=page)}}
Here is a twiddle that just scrolls down to the relevant page.
I'm not sure if you want to handle the scroll event ? In that case, the twiddle and relevant components will need to be expanded.
{{scrollable-pages pages=pages activePage=page onScroll=(action "changeActive")}}
So that you can handle that action and change the active page.
I would even consider another parent component in this case to manage the state, injecting a service with the pages, and handling the scroll change there.
Related
I know the concept of Data Down / Actions Up, but I'm facing a situation on which I don't know how to do it with the DDAU. I searched on differents forum and blogs how to do it, but it does not fit my request.
I have a controller with two components.
On the first component I have a header with a button.
On the second component I have a form.
When the button is clicked, an action is trigered and catched by the controller, but how can I notify the second component of the "click" on the button on the first component.
An easy solution would have been to include the first component in the second one, but I can't do this because each component are used in many different situations.
You can use services as a bus.
Register an event on second component and trigger that event from first component.
I show it in this twiddle
If you don't want using services you can use parent-child model.
Please take a look at that twiddle
You can pass foo property from controller to both components, and first component to pass action to controller to change foo. Now this sibling component too will be notified and you can make use of didUpdateAttrs hook in sibling component to react to change.
I have a mixin for Ember components, named in-view, the job of which is to request that that the element be brought in view. It is provided an attribute whose value is an piece of content to be brought into view, and if that attribute matches the component's content then I call scrollIntoView or the equivalent. The code looks something like this:
// calling template
{{#each items as |item|}}
{{my-item content=item inViewItem=inViewItem}}
}}
// mixins/in-view.js
scrollIntoView() {
if (this.get('content') === this.get('inViewItem'))
this.get('element').scrollIntoView();
}.on('didInsertElement')
// components/my-item/component.js
import InView from 'mixins/in-view';
export default Ember.Component.extend(InView,
This works fine. The question I have arises when I want to change the item in view. I can have the in-view mixin observe the inviewItem attribute:
}.on('didInsertElement').observes('inViewItem')
and this also works, but seems like a bit of a code smell.
In addition, my actual code structure is that there is a controller which knows which item is supposed to be in view, and then its template calls a my-item-list component which displays the scrollable div containing the item list, and that in turn calls the my-item component. This means I have to pass the inViewItem attribute from the controller down through two levels, as in
// resource/controller.js
inViewItem: something
// resource/template.js
{{my-item-list items=item inViewItem=inViewItem}}
// components/my-item-list/template.js
{{#each items as |item|}}
{{my-item content=item inViewItem=inViewItem}}
}}
I could avoid this by having the my-item template hard-wired to access the inViewItem attribute on the controller:
scrollIntoView() {
if (this.get('content') === this.get('controller.inViewItem'))
this.get('element').scrollIntoView();
}.on('didInsertElement')
but that's another code smell; I don't want to build this kind of dependency on a specific controller field into the mixin. Instead I could possibly pass the component the name of the controller attribute to watch, but this seems unduly clumsy, and it's tricky to observe an attribute whose name is variable. More importantly, I don't think this will work when controllers go away in 2.0.
What I want essentially is a way to "ping" or somehow send a message to a template. I know that in principle this violates the DDAU principle, but in this particular case what I need is exactly to somehow send an "action down"--an action telling the component to adjust itself to bring itself into view.
Of course, I could give up on the entire idea of the in-view mixin and simply have the controller dig down into the generated HTML to find the item to bring into view and issue the scrollIntoView on it directly. However, this seems to violate some principle of separation of concerns; the my-item template would no longer be in complete control of itself.
What is the recommended design pattern for this kind of case?
The solution here is to go the opposite direction that you have. Your component here is a localized scope, and the pain you are feeling is that your localized scope needs to access and mutate global state (the app's scroll position).
Some people use a scroll-service for keeping track of and mutating state, I've used several variations on that myself.
It sounds though like you're dealing with a scrollable list, perhaps a div, and that what item is in view isn't merely a function of page state, but programmatically may change. For instance, a new item has been inserted and you want to scroll the new item into view.
A plugin like jquery.scrollTo or similar (collectively "scroller") would be better for that than simply jumping to the new position as it preserves the user's contextual awareness to where they are on page.
With a scrollable div or list or similar, you might choose to have your top level component control scroll state. The scroll state is still localized in this case, but instead of being localized to each item it's been localized to the scrollable region as a whole, which is where it better belongs.
There are a number of patterns for list items to register themselves with a parent list-component. In a robust scenario, I might do so, but a quick and not very dirty approach is to do something wherein on didInsertElement the new child emits an action to the parent containing it's context, which the parent then uses to check if it's the active item and if so triggers the scrollTo.
I have an application where we'd like to use a <select> element to control which object is loaded in a detail route.
If this were a normal <ul>, like if I were using bootstrap's drop-down, using the #link-to helper would be perfect here, because I could use the active class to always automatically select the item that is loaded in the child route.
With a select element it's a little different. I'll probably need to write a view, I'm okay with that, but it occurs to me that parents aren't supposed to know about their children in ember, so how does a parent view get access to know which child view is currently selected?
Even a link to how the link-to helper is implemented could be helpful here.
Thanks!
If I'm interpreting this correctly, you're looking to change the URL when the <select> option changes.
With a combination of transitionToRoute, observes, and currentPath you can achieve this using the built in Ember.Select view class.
Here's a JSbin that might help:
http://emberjs.jsbin.com/jogadudase/2/edit
parents aren't supposed to know about their children in ember
Where does this come from?
I'm not 100% sure of what you want to accomplish, but you probably want to use one of this: Ember.ArrayController or Ember.CollectionView.
With either of those you can have control over children objects.
I'm working on a events board app. Events are displayed in columns at the height matching the start time and pack into the space if there is more then one overlapping. Each event is a view and I want to have a div next to the view that shows and hides on hover.
I know how to bind to mouseEnter and mouseLeave to show and hide part of the template but I want to show something adjacent to my view/template not within it.
I've already got some computed properties on the view to place the event with the correct height and width so I don't want to add the popover inside the view.
Here is something to mess with http://jsbin.com/osoner/1/edit
Seems like something simple but I want to make sure I'm doing things the Ember way.
After messing a little with your provided jsbin, here the results.
Basically what I've done was adding a new popup css declaration wich do position the popup so that it appears outside the parent view, and also moved the {{#if...}} helper into the originating view.
If you want to go more fancy, checkout this jsfiddle wich uses the twitter boostrap popover.
Hope it helps.
I have a computed property that acts as formatter. Example fiddle to show basic functionality here
, http://jsfiddle.net/mlienau/xSkyd/2/.
I haven't implemented this functionality in the example, but the end user of this can remove terms by dragging them out, using draggable from jquery-ui . I was accomplishing this using a jquery live on mouseover of the element, but on ipad it doesn't work. Adding touchstart to live event is a hack because the user has to touch it once, before they can drag it out.
So my main question is: Is there a way to determine when a computed property has been inserted into the DOM like there is with view and didInsertElement, so I can set up the draggable handle there? Also, I am aware of some non-ideal ember practices in the example. Thanks!