In an angular5 application, I have various sections of my page layout that I would like to control through an angular service. For example, I have a sidenav component that displays when a value is set to open, and I would like to be able to toggle it from any component I'd like.
My initial thought was that it would be nice if I could bind the open value to a variable in a LayoutService I would create, and the LayoutService would contain a toggle() method that would toggle the value and cause the sidenav to open/close. I could then inject my LayoutService into any component I'd like and control various parts of my layout.
Any idea whether this is possible and how I could go about doing this? I thought it might be possible using an EventEmitter or something, but I was wondering whether there was a simpler way and I'd rather not use redux.
https://stackblitz.com/edit/angular-lj7gsz
Here's a side-bar you can open and close using simple rxjs objects.
In the side-bar service, I've created a BehaviorSubject that you can pass boolean values to and I also exposed an Observable, which will emit every time a new value is passed to that subject.
By subscribing to that observable (I've used the async pipe to subscribe for me), my side-bar component will know when other components wish to open or close the side-bar. All the other components need to do is inject the service and call the service's open or close methods.
It's not perfect, but I feel it's definitely better than using event emitters as they were never made to be used in services.
Hopefully this is helpful.
Related
I have been developing a Vue project and something caught my attention today. I used checkboxes with some sytling (I use them as toggle switches) throughout the project and thanks to these elements, I show or hide some elements and components. Toggle elements control specific data within each component. When the data istrue, some elements are displayed on the page and when false, they are hidden. What I noticed today is a little interesting. There is probably a simple solution, but although I have been searching the internet for a while, I haven't found a solution yet.
Here is the thing;
Let's say I am at the About page of my project. I used my toggle switches and now some of my elements and some sub components are displaying in the About.vue. Then I go and visit my Services.vue page and showing and hiding some elements and sub components as well. By the way, almost all of these pages have forms and I save these forms to local storage. When I return to My About page from my Services page, I see that the elements I activated have been restored. In other words, each component welcomes me with its default state when it is returned from another component. What I want to see is, If I go and check some checkboxes to show some element, No matter how long I roam between other routes, I want those elements to remain visible or hidden when I come back. For example, a toggle element must be activated to write a username and password on a component. After activating the toggle element, the user types the username and password and clicks the Save button. Then he continues to browse many areas of the project and when he returns, he sees that the toggle element is inactive and the username and password are not entered. I don't want it to be that way. How do I fix this?
you can use vuex for solved this problem.
https://vuex.vuejs.org/
Vuex is a state management pattern + library for Vue.js applications. It serves as a centralized store for all the components in an application, with rules ensuring that the state can only be mutated in a predictable fashion. It also integrates with Vue's official devtools extension (opens new window)to provide advanced features such as zero-config time-travel debugging and state snapshot export / import.
For example, I have two async services. Let's assume that both services are available in the moment of app loading and signal that by returning true. I have two properties ('servconn' and 'netconn') that receive those boolean flags. Then I'm passing these two properties to a separate component as props. On that separate component, I have two alert boxes that show depending on the availability of the services.
If you look at the example sandbox, the problem is that the alert boxes are staying still before the component receives flags.
Of course, if I change initial flags to true in the data() section then all works but it's logically not correct and also, flags can be different depending on services availability. Which is the right way to accomplish this? Is there a better way to do this? Thank you.
Click the refresh sandbox icon button to see how it works.
Here is the Sandbox
I would like to know the best practice for implementing shared states between components in Vuejs.
Imagine situation A: you have a web app that shows a modal. The modal has the boolean state show. This state should change if the modal OK-button is clicked, but also if any part of the background is clicked, and perhaps even on some server pushed state change. Thus the modal should be able to change the state as should the parent app.
Situation B: you have a web app that shows input fields inside different components that share a common data value. If the user changes value through the field in one component, it should also update in the other. Again both should even update on a server push event.
Questions:
I am right that the correct way to go about this would be to use vuex and make the shared state a store field that is observed by and changed through emitted actions by all components / parents that need to modify that value?
Does that not introduce this kind of dangerous (since hard to handle) magic reactivity that we know from Meteor?
How to best document the flow, what depends on what?
A: For a modal component, I'd say that show should be a prop. So the parent component can control the modal whatever it wants. In this case there is no shared state at all.
The modal itself doesn't need to know anything about the server. If the prop show is true, just display the modal and vice versa.
I think the mask layer is a part of the modal, so when the mask is clicked, the modal emits an event. The parent component receives the event and can decide to hide the modal or not to.
Vue has an official modal example here (thanks #craig_h for mentioning): https://v2.vuejs.org/v2/examples/modal.html
B: Just bind the vuex state to the inputs. Nothing wrong.
Note that not all the components need to access the vuex store directly. For some pure UI components, just use props. So the parent components have the right to control them and increase flexibility.
I recommend you to read these docs:
https://facebook.github.io/react/docs/lifting-state-up.html
https://medium.com/#dan_abramov/smart-and-dumb-components-7ca2f9a7c7d0#.j7ry4a3as
http://redux.js.org/docs/basics/UsageWithReact.html
Yes these are React / Redux docs. Since Vue is relatively young, react community has more documentation / articles. But both Vue and React are component-based libraries. The idea of how you design a component is basically the same.
You can also take a look at this vuex example: https://github.com/vuejs/vuex/tree/dev/examples/chat
This is a very simple example but it does use all the things I mentioned above. Emitting an event, some pure UI components...
I've got an existing SPA that was developed using nested RactiveJS components. Which is great, and offers a ton of flexibility throughout the entire app. Currently I attempting to add in client side routing support using page. My navigation switches out high-level components using simple {{#visible}}{{/visible}} template markup on each component. This is a little troublesome in its current state as it always kicks off a re-render whenever the high-level component becomes visible again.
Is there a way to render a component, for example, called widget, without using the
<widget></widget>
method? I've already "registered" the component with the parent, but obviously when constructing it by means of
new App.components.widget
I am able to control how/when it's rendered/inserted/detached, but lose the recognition in the application's component hierarchy.
There is insert exactly for that. You don't even need to "register" it to the component you plan to put it to. You can use the different find* methods or nodes to easily retrieve a reference of your planned container element.
var instance = new YourDetachedWidget({ ... });
instance.insert('#your-container'); // This could be a node, selector or jQuery object
Is there a way to communicate from the parent viewmodel to a KnockoutJS component?
I have a component that contains a bootstrap modal dialog box, to search for customers and return a selected customer. At present, to make the dialog box appear, I pass an observable boolean from the viewmodel in the component's params attribute. To make the dialog appear I set this to true, which invokes the dialog box. I also pass a callback function in params to return the results.
Here is a fiddle demo which shows the concept: http://jsfiddle.net/Quango/5bxbsLt6/
Passing the observable boolean to invoke the dialog doesn't feel right, but it's the only working solution I have. The only other idea I had was to use ko-postbox to create a publish/subscribe function.
It feels like there should be a way to invoke actions, e.g. component.Show() ?
I think the answer here is that there isn't a better way. To communicate from a parent viewmodel to the component, pass an observable value, and then use that directly or subscribe to changes in the component.
I will put a suggestion on the Knockout github project to consider some form of interface.