I have a vue3 webapp that I use to edit some multi-pages documents.
All the pages are stored in a state with pinia. My pinia state is an object with a pages property that is an array containing all the data of each page.
Each page of each document use a specific template, so I created multiple components to handle each template, and I also have subcomponents for some parts that can be found across multiple templates.
I loop through the pages with a root component, passing a reference to the page object, like it :
<PageWrapper v-for="page in pages" :key="page.id" :page="page" />
Then, inside the PageWrapper component, I use the according page template's component, passing along a reference to the page object (the same with subcomponents if any) :
<PageFirst v-if="props.page.type === 'first'" :page="props.page" />
<PageServices v-if="props.page.type === 'services'" :page="props.page" />
<PageTotal v-if="props.page.type === 'total'" :page="props.page" />
<PageContent v-if="props.page.type === 'content'" :page="props.page" />
I wonder what would be the best way to edit a property of my page object from a subcomponent, as I know that it is a bad practice to mutate the property directly.
Do I have to use events ? Is PageWrapper the good place to catch all the events and the modifications?
Any advice on this matter would be of great help to me.
Thanks a lot for your help!
As the Vue official document point out:
In most cases, the child should emit an event to let the parent perform the mutation.
So the answer is you should let the parent do the job of mutating the props. And it will never be a bad solution.
But, look at your design. Your parent component PageWrapper works just like a wrapper. It does nothing but a container for its child.
The props one-way data flow prevents child components from accidentally mutating the parent's state, which can make your app's data flow harder to understand. But if the parent does not actually handle state and your child component's data does not relate with each other, mutating the props inside the child component will be fine.
Related
I would like to know what the best practice is for a communication between parent/child components. I have read this blogpost about communication and components states but haven't found the right answer for my problem.
Following components are considered.
My parent component is a List, which renders several Tasks (child component) from objects in the parent component.
So my questions are:
Is it best practice to pass the object to each Task component?
When a value has changed in the Task component, how does the parent component know about this? Because the parent should know about the infos of all children.
So is this a right pattern to use?
In my Parent Component I have this in the render function:
<Task key={index} taskdata={taskobj} />
My Task child component looks like this:
render() {
return (
<input type="text" name="wunsch" defaultValue={this.props.task.title}/>
);
}
So if the value of the input field will change, does taskobj in the parent component also change? In this example no. But what would be the right pattern here?
Basically when you want to pass information from parent to children you use props, when you want to pass information from child to parent you pass a function to a child as a prop and then call it when you need to update a parent.
You can read more in official docs
Also you can take a look Reflux.
A simple library for unidirectional dataflow architecture inspired by ReactJS Flux
In React, data flows one way
I wasn't really aware of this React concept.
So after reading this link in the ReactJS Doc I decided to the onChange/setState() way as ReactLink is already deprecated.
So when a change in the model happens in the child component I call a method in the parents component to update (setState) my data.
Suppose I've got comments list component with comments components. I wanna implement method that will return all comments components. I assigned to each comment component same ref:
<comments>
<comment ref="myComments" text="abc" />
<comment ref="myComments" text="efg" />
</comments>
I thought I can access all my components by this.refs.myComments but it doesn't work - it returns only last comment component.
What's the correct way to access all comment components?
There is no correct way to do that.
Your view is a representation of your data, so if you want the text for all comments, look at the data.
If you want to update the comments, update the data.
Pulling data out of the view, or manually manipulating the view defeats the purpose of react.
I have a checkbox in a component:
<s:CheckBox id="myCB_1" />
In my main.mxml I need to test for the state of the checkbox. I originally had all my code in main.mxml, but it was getting really long, and I thought that it was better practice to break my code into components. Also, I have other projects where the same concept will apply, so I really want to figure this out.
I have the following function :
private function checkAlarms(currentTime:Date):void
{
if (!breakfastAlarmSounded)
{
if ((currentTime.hours > breakfastTime.hours) || ((currentTime.hours == breakfastTime.hours) && (currentTime.minutes >= breakfastTime.minutes)))
{
if (myCB_1.selected)
{
playBreakfastAudioAlarm();
}
if (myCB_2.selected)
{
playBreakfastVisualAlarm();
}
breakfastAlarmSounded = true;
}
}
...
simply addressing the component, as in:
myComponent.myCB_1.selected
doesn't work. Someone mentioned that I need to create a variable in my component that refers to the id (myCB_1) of checkbox, but I don't really understand or know how to do that, and they didn't elaborate.
How do I test for the status of the CheckBox "myCB_1" in the component from within my main.mxml?
many thanks,
Mark
(newbie)
With very little information, I'm going to suspect you originally had the CheckBox included in main.mxml and moved it to a custom component. If so, you need to address the CheckBox's ID via the custom component's ID. Something like this (from main.mxml):
if(yourComponentsID.myCB_1.selected)
{
...
}
If this isn't the case, please edit your post and give us more detail.
EDIT
You said you created a new custom component and moved the CheckBox into it. Great, that's a helpful start :) When you included your new component in your main.mxml file, it should look something like this:
<component:YourNewComponent />
Of course, however you named it (and whichever namespace is used to reference it) will be different from my example, but the principle should still apply. In main.mxml, you need to give your custom component a unique ID string so you can reference it within main:
<component:YourNewComponent id="myComponent" />
From here on, you should be able to reference the component, and any public elements within it: myComponent.myCB_1.
It would be useful to provide more details about the context in which you're using this script. Nonetheless I'm going to throw out some information that may help.
In order for the script to access the component, it has to be within the scope of the component. Usually that means one of the following:
You have a <script> tag in the MXML, with code in it that references components within the same MXML file.
You have a <script source='external.as'/> tag in the MXML, where external.as is referencing components in the MXML file.
You are creating the component in your script and you have a definition for the component within ActionScript (ex. var myCB_1:CheckBox; is within the class definition).
If the script and the component aren't within the same scope then they can't see one another.
You need to refer to the checkbox through the component. Lets say that you use your component in your main like this:
<local:MyComponent id="myComponent" />
In your script, you want to refer to it:
if(myComponent.myCB_1.selected) { // do something }
Strangely enough, it works. I was getting a getting an 1119 error (Description 1119: Access of possibly undefined property myCB_1 through a reference with static type Class.) when I refer to the component with dot notation (myComponent.myCB_1.selected) and an 1120 error (Description 1120: Access of undefined property myCB_1) when not addressing it via myComponent.
With these errors I never thought to try running the thing. Long story short - it runs with or without addressing the component (???) go figure!
thanks for all the input and would love to hear any other comments.
MCE
I currently use: Flexglobals.toplevelapplication.component1.compnent2.currentState = 'something';
is there a better way of doing do? Can I bind the state of a components to variable in my model?
Ideally, components should be self contained little pieces of your application. One component shouldn't have any effect (including changing the state) on any component, except possibly it's children.
The "Encapsulation proper" approach to change the state of an unrelated component is to dispatch an event from the component. The component's parent (or some component higher up in the hierarchy chain) is going to execute an event listener and change that state of the appropriate component, by either calling a method on the component that needs a state change or changing a property on the component that needs a state change.
If you have a complicated hierarchy, this approach can lead to a lot of tedium, creating events up the chain, and creating properties / methods down the chain in order to preserve encapsulation. Some frameworks, such as Cairngorm introduce a global singleton to avoid this tedium. In Cairngorm that singleton is the ModelLocator.
The ModeLlocator is, basically, a global dependency in your application. You can give any component access to it, and through the use of binding if a property is changed in one place, it an be automatically updated elsewhere. To change the state using binding, use an approach like this:
In the ModelLocator, create a variable to hold the state for the view in question:
[Bindable]
public var comp1State : String = 'defaultState';
In comp1 do something like this:
<mx:Container currentState="{model.comp1State}" otherComponentProperties>
<!-- other component code including defining the states -->
</mx:Container>
Then in the component where you want to change the state, do something like this:
model.comp1State = 'nextState'
Binding will take it from here. I wouldn't use his approach lightly though. It depends on the component you're trying to create and how much you car about reuse. The most common way I've seen this implemented is not with states, but with the selectedIndex in a ViewStack. But, the approach would be the same.
Yes. I usually bind the sate of my component to a property in my model.
As long as you are making the properties on your model bindable you should be able to bind
directly to you model in your view. You sitl have to set the state in you model. Id look into using a framework like [swiz][http://swizframework.org/] or or mate.
Are there any way to declare a child component in mxml which is private/protected or even static?
Sure we can do this inside a script tag, but are there any other way?
Ashier suggests using the "Exclude" metadata tag, but Maskit offers its limitations and suggests alternative solutions:
http://blog.ashier.com/2008/03/25/hiding-properties-in-flex-components/
http://smaskit.blogspot.com/2008/07/making-mxml-subcomponent-private.html
In the strict meaning of these terms, no you can't do that using mxml. The second link posted by Luis contains some workarounds for private/protected behavior.
I found a solution to the static question. I wanted a quick memo pad that could be accessed anywhere in the mobile app, without one instance overwriting edits left open in a different screen.
I created a memo pad mxml control, and then placed it inside a declarations section in the top level application mxml. In each view that I wanted the memo to appear in, I added:
import mx.core.FlexGlobals;
import components.QuickMemo;
private var memo:QuickMemo;
In the view creation complete:
memo = FlexGlobals.topLevelApplication.memo;
In the viewActivation code, I added:
memo.visible = false;
addElement(memo);
In the viewDeactivation code, I included:
removeElement(memo);
The net effect is that only one instance of the memo exists at any time, and that one instance opens in whatever state it existed in the last view it appeared in.