How can I access child component data from a parent in Vue? - vue.js

I am trying to access data from a single-file component in Vue, but can't find any way of doing it. I have tried using $emit, but can't get thath to work either. The data string has to be blank as it gets modified by an input field.
I have seen others' solutions here on SO, but either the don't fit with my problem or I can't get them to work. I want to try to keep it as simple and understandable as possible.

You can use the special attribute ref:
<child-comp ref="child"></child-comp>
In JS:
vm.$refs.child.YOUR_DATA
Hope this helps!

Related

Vue3 computed property in parent child component structure not working

After trying to find solution to this issue for hours on various forums i am posting this here.
So i have two components. 1) App and 2) Todo. Both renderes a list and i can complete items so there will be two lists one for incomplete items and one for complete items. you can click on item and it will be gone to complete items list.
So in my example you can see i am using same component but with two diffreent ways to give data to component. one using API and one using native js Data. in both cases it renderes but with api i can click on list item and it will be gone to completed list but with javascript array example it doesn't work. i am completely amazed with this because component is same. how it can affect like that.
many answer here do tell me that computed properties are not reactive as they are cached but what’s the solution to that ? i can put data variable but then the first case of api will not work because time it takes to fetch it. so please help me with this one.
complete code at sfc playground
You have reactivity issues the computed property probably expects that value to be constant because you provide a non-reactive array from the parent.
I think you have 2 options here:
you either provide a reactive prop from parent
or you set a local data attribute in the child-component so that vue will know that it can change
Your fiddle didn't work for me so I copied your code to codesandbox, I have both examples there but commented out the first solution, there you basically simply add the array to the data object and reference that in the code.
Second solution you can add a mounted hook to define reactiveAssignments to your data in the child component this way it will have the same reference so that's why it would work that way.
I think the first solution is simpler, but it is really up to which one you prefer.
You can check the solutions here in my codesanbox
A better approach could be though by setting up component events instead of v-models in the child you should use it in the parent because this way you are directly modifying the props. You can read more about this here: https://vuejs.org/guide/components/events.html#usage-with-v-model

Is it possible to have dynamic element names in a Vue template?

I need to have a component, where I get the type of another component that this component should create. (it could be one of n different elements) Doing this in the component's render function is not a problem, but since I am new to Vue and I am trying to do things the Vue way, not the way I would do it in React.
I have not been able to find any solution with just using a Vue template. Is there one?
This is how I would like to be able to use the component:
<factory elm="first-component"></factory>
The factory should then internally in some way result in this:
<first-component></first-component>
(it should also be able to add attributes to the component, but that I know how to do, so a suggested solution does not need to care about attributes)
There is <component :is="myCoolComponent"></component> that will basically generate <my-cool-component></my-cool-component>.
Is it what you're looking for?
From the documentation: https://v2.vuejs.org/v2/guide/components-dynamic-async.html#keep-alive-with-Dynamic-Components
You could also totally create a Factory.vue component and put that kind of logic inside of it (<component :is="" ...>).

Is there a way to highlight required input fields in Vue Formulation?

So I am trying to create a form using Vue Formulation. I have a few input fields that are required. Is it even possible to highlight them somehow? I have read Vue Formulation doc, but could not find the answer.
You could simply give the required fields a different styling/CSS class.
If you are really fancy, you could try to read the attributes of the DOM elements (with attr() or refs), but haven't tried that and it is probably not worthwhile.

How to update vue2-frappe chart?

I've been breaking my head over this for the last few hours and no matter where I look I can't seem to find the answer.
I'm using vue2-frappe as my chart library. I'm using a simple bar chart to display certain values by day. Everything was fine until my higher-ups decided they wanted to show a whole year's worth of values on this chart, meaning I have to add some pagination to it.
The problem is, now I can't figure out how to make the chart rerender. I've tried replacing the entire object I've bound the chart to, as well as manipulating specific values, but nothing seems to make the component rerender.
In the documentation for frappe.js, you can modify data via specific methods, but this being Vue I can't just call chart.update() like in normal .js. And if I inspect the component via vue dev tools, I can see it contains the modified data, it just doesn't redraw itself.
Anyone have an idea what to do?
I would try to force update the view component.
VueJs reactivity can sometimes be confusing where you think it should react to changes but it doesn't.
You can force a view update like so:
// Globally
import Vue from 'vue';
Vue.forceUpdate();
// Using the component instance
export default {
methods: {
methodThatForcesUpdate() {
// ...
this.$forceUpdate(); // Notice we have to use a $ here
// ...
}
}
}
You can read about correct ways of re-rendering here: https://michaelnthiessen.com/force-re-render
There are caveats to this approach as outlined in vueJs's docs: https://v2.vuejs.org/v2/guide/list.html#Caveats
Note #
A force re-render wont update computed values, but your computed property shouldn't contain any external non-reactive variable anyway.
Note 2
The above article written by Michael Thiessen also states the best way in his opinion is key-changing which I think we all should be aware of.
I hope this puts you on the right track. It sounds like (with limited information) you could be replacing the data but using the same key.

Is it possible to use more than one "template" element in one component in vuejs?

This question triggered in my mind while reading through Vue's official guide here.
I don't know if I find the answer to this question on proceeding further to read more from the official guide, but curious to know if it's possible or not.
Well, I'll update here as soon as I got to know the answer.
Screenshot from official guide
A component must use a single template or component option object, and that template must provide a single root element to mount. The template is converted into a render function internally, and Vue can only have 1 render function.
Your component can in turn contain a component that is dynamic, however.
https://v2.vuejs.org/v2/guide/components-dynamic-async.html