When I have a textarea like
<textarea v-model="foo.abc.text"></textarea>
and either foo or foo.abc does not exist yet then
vue removes either parts of the DOM or is giving me a blank page.
It does never recover.
That alone is annoying, regardless of if I am using a debug version of vue or not.
If I try to use an approach that I have been advised to use earlier like
<textarea v-model="foo?.abc?.text"></textarea>
then I am still out of luck, I presume that I get a "rvalue" using those question marks and what I need rather is a variable location.
How do I, with as little trickery as possible, allow v-model to exist later on even if it doesnt exist now (late binding)?
Just shape your data accordingly and initialize it with empty values:
data(){
return {
foo: {
abc: {
text: ''
}
}
}
}
You can later populate it e.g. with the result of api call, but it's still better to initialize data properly
I would suggest going the :value + #input way. It allow more control over the input model, and does not require hiding it.
<textarea :value="!!foo && foo.abc.text" #input="(val) => !!foo && (foo.abc.text = val)" />
You can even hook in a validator:
<textarea
:value="!!foo && foo.abc.text"
#input="(val) => !!foo && (foo.abc.text = val)"
:rules="v => !v && 'The object has not been initialised'"
/>
I found a solution I can live with and then I got a comment in the same direction:
Conditionally showing the textarea.
v-if seems to do it but it falls under the "trickery" category, I think (angularjs would be more relaxed).
<textarea v-if="foo!=null" v-model="foo.abc"></textarea>
The symptom to hiding components if something is not all correct is not the best part of vue.js. Better show them and color them red.
Related
A simple question in Vue.js. In this code, the second "project" don't have any "Property", obviously no "Number", this make the html shows blank, how to handle this when there's no data in the array? I've tried v-if but can't make it work. Thanks
<div v-for="propiedad in info" class="propiedad">
<div class="propiedad">
{{ project.Property[0].Number }}
</div>
</div>
I take the question "this make the HTML shows blank" as "There is some errors in the console and the entire page fails."
You can do it by
project && project.Property[0] && project.Property[0].Number
Or if you are working with babel with plugin babel-preset-env, you can take advantage of the optional chaining feature
project?.Property[0]?.Number
First, this looks off because of the loop that you are not using. (Is there a mistake or why bother showing it?)
A v-if should work, but it often gets verbose.
<div class="propiedad" v-if="project.Property && project.Property.length > 0 && project.Property[0].Number>
That should cover all the bases.
Therefore it's often cleaner to massage the data beforehand. Maybe make all projects have defaults.project.Property, so you don't have to check if it exists.
Or just make computed properties so your template can look nice
computed: {
hasProperty(){
return this.project.Property
&& this.project.Property.length > 0
&& this.project.Property[0].Number
}
}
<div class="propiedad" v-if="hasProperty"> ... </div>
Or if this is indeed related to the loop . Make a computed array that filters the array.
computed: {
// Here I make the wild assumption that info are actually projects
// (just to make the loop relevant)
filtered(){
// Skip all the projects without "Properties".
return this.info.filter( i => i.Property.length > 0 )
}
}
<div v-for="propiedad in filtered"> ....
I have an issue with complex object reactivity.
I've read everything I can on stack to find a way to solve it, but nothing works. I've looked at object reactvity and array caveats on vuejs, but not working either.
So I'm asking some help please.
Let me explain the project:
I have 2 columns :
- on the left side, I CRUD my content
- on the right side, I display the results
I have my object, and I'm adding new elements on its "blocks" property (text, images, etc...)
[
{
"uid": 1573224607087,
"animation": "animationName",
"background": {
"bckColor": "#ff55ee",
...
},
"blocks": []
}
]
On click event, I add a new element via this method. Everything is ok, I can CRUD a block.
addBloc(el) {
if (el.type == "text") {
const datasA = {
type: "text",
uid: Date.now(),
slideId: this.pagination.currentPage,
content: el.content,
css: {
color: "#373737",
...
},
...
};
this.slides[this.pagination.currentPage].blocks.push(datasA);
this.$bus.$emit("newElement", datasA);
}
To modify the order of my elements on the display side, I added a drag and drop module to move my block on my DOM tree. Smooth dnd
The problem is, when I drang&drop my element, my object is updated correctly, but the DOM isn't. The dragged element goes back to its initial position.
What is strange, when I try to modify my block (the one I dragged), it modifies the other one.
I'me adding a small video, so you can see what's happening.
Small animation to show you what's going on
I add some more explainations.
I use event bus to communicate between my components, and the right side is using its own object!
I don't know how I can solve this issue.
Tell me if you need more information.
Thank you all !
EDIT 1 :
I added an id to each block to see what happens when I start Drag&Drop. ==> blocks are moving correctly. The problem is not coming from the method onDrop() but from my nested components if I understand well. They don't update. I'm going to search for this new issue.
I've added a new gif to show what's going on.
This is the nested structure
TheSidebar.vue => top container
<Container
:data-index="i"
#drop="onDrop(i,$event)"
:get-child-payload="itemIndex => getChildPayload(i, itemIndex)"
lock-axis="y"
>
<Draggable
v-show="pagination.currentPage === i"
v-for="(input, index) in slides[i].blocks"
:key="index.uid"
:id="'slideBlocksContainer'+index"
class="item"
>
blockId #{{input.uid}}
<AppContainer
v-if="input.type == 'text'"
:blocType="input.type"
:placeholder="input.content"
:id="index"
:slideId="i"
></AppContainer>
</Draggable>
</Container>
Then I have my AppContainer.vue file, which is a top level. In this I have the specific elements of each input type
And I have AppElement.vue file, which is common elements, I can use everywhere
Something like this
TheSidebar
--AppContainer
----AppElement
Know I don't know yet, how to force vue to update AppContainer.vue and AppElement.vue
EDIT 2 :
As suggested in this article I've changed the key of the component and now , when I drag and drop my elements, they stay where they are dropped.
What I see also, is that the AppElement inputs, are related to their own AppContainer. So everything is ok now, but I don't know if it is best practices.
The issue appears to be that the Smooth dnd library you are using is not updating the array of blocks that you are passing to it, it is likely making a copy of the array internally. So when you change the position of the blocks by dragging and dropping, you are not changing your blocks array, just the internal copy.
Looking at the Smooth dnd documentation, if you wanted to access the modified array you could try using the drag-end event handler:
onDragEnd (dragResult) {
const { isSource, payload, willAcceptDrop } = dragResult
}
Vue is not registering event handler for HTML injected objects. How do I do this manually or what is a better way to work around my problem?
Specifically, I send a query to my server to find a token in text and return the context (surrounding text) of that token as it exists in unstructured natural language. The server also goes through the context and finds a list of those words that also happen to be in my token set.
When I render to my page I want all of these found tokens in the list to be clickable so that I can send the text of that token as a new search query. The big problem I am having is my issue does not conform to a template. The clickable text varies in number and positioning.
An example of what I am talking about is that my return may look like:
{
"context": "When in the Course of human events, it becomes necessary for one people to dissolve the political bands which have connected",
"chunks": ['human events', 'one people', 'political bands']
}
And the resulting output I am looking for is the sentence looks something like this in psuedocode:
When in the Course of <a #click='search("human events")'>human events</a>, it becomes necessary for <a #click='search("one people")'>one people</a> to dissolve the <a #click='search("political bands")'>political bands</a> which have connected
This is what I have tried so far though the click handler is not registered and the function never gets called:
<v-flex xs10 v-html="addlink(context.context, context.chunks)"></v-flex>
and in my methods section:
addlink: function(words, matchterms){
for(var index in matchterms){
var regquery = matchterms[index].replace(this.regEscape, '\\$&');
var query = matchterms[index];
var regEx = new RegExp(regquery, "ig");
words = words.replace(regEx, '<a href=\'#\' v-on:click.prevent=\'doSearch("'+ query +'")\'>' + query + '</a>');
}
return words;
}
As I said, this does not work and I know why. This is just showing that because of the nature of the problem is seems like regex is the correct solution but that gets me into a v-html injection situation. Is there something I can do in Vue to register the event handlers or can some one tell me a better way to load this data so I keep my links inline with the sentence and make them functional as well?
I've already posted one answer but I've just realised that there's a totally different approach that might work depending on your circumstances.
You could use event delegation. So rather than putting click listeners on each <a> you could put a single listener on the wrapper element. Within the listener you could then check whether the clicked element was an <a> (using event.target) and act accordingly.
Here's one way you could approach it:
<template>
<div>
<template v-for="segment in textSegments">
<a v-if="segment.link" href="#" #click.prevent="search(segment.text)">
{{ segment.text }}
</a>
<template v-else>
{{ segment.text }}
</template>
</template>
</div>
</template>
<script>
export default {
data () {
return {
"context": "When in the Course of human events, it becomes necessary for one people to dissolve the political bands which have connected",
"chunks": ['human events', 'one people', 'political bands']
}
},
computed: {
textSegments () {
const chunks = this.chunks
// This needs escaping correctly
const re = new RegExp('(' + chunks.join('|') + ')', 'gi')
// The filter removes empty strings
const segments = this.context.split(re).filter(text => text)
return segments.map(segment => {
return {
link: segment.match(re),
text: segment
}
})
}
},
methods: {
search (chunk) {
console.log(chunk)
}
}
}
</script>
I've parsed the context text into an array of segments that can then be handled cleanly using Vue's template syntax.
I've used a single RegExp and split, which will not discard matches if you wrap them in a capture group, (...).
Going back to your original example, v-html only supports native HTML, not Vue template syntax. So you can add events using onclick attributes but not #click or v-on:click. However, using onclick wouldn't provide easy access to your search method, which is scoped to your component.
If i open https://v2.vuejs.org/v2/guide/forms.html#Text and edit text - no effect on typing text in mobile chrome. #keyup #input #keypress - v-model does not change when I'm typing
<input v-model="message" #keyup="log" placeholder="Edit">
<p>Edited: {{ message }}</p>
How can i fix it? I need get input value on typing (#keyup #input)
Update: After a lot of discussion, I've come to understand that this is a feature, not a bug. v-model is more complicated than you might at first think, and a mobile 'keyboard' is more complicated than a keyboard. This behaviour can surprise, but it's not wrong. Code your #input separately if you want something else.
Houston we might have a problem. Vue does not seem to be doing what it says on the tin. V-model is supposed to update on input, but if we decompose the v-model and code the #input explicitly, it works fine on mobile. (both inputs behave normally in chrome desktop)
For display on mobiles, the issue can be seen at...
https://jsbin.com/juzakis/1
See this github issue.
function doIt(){
var vm = new Vue({
el : '#vueRoot',
data : {message : '',message1 : ''}
})
}
doIt();
<script src="https://cdn.jsdelivr.net/npm/vue#2.5.16/dist/vue.js"></script>
<div id='vueRoot'>
<h1>v-model</h1>
<div>
<input type='text'
v-model='message'
>
{{message}}
</div>
<h1>Decomposed</h1>
<div>
<input type='text'
:value='message1'
#input='evt=>message1=evt.target.value'
>
{{message1}}
</div>
</div>
I tried all solutions I could find on the internet, nothing worked for me. in the end i came up with this, finally works on android!
Trick is to use compositionupdate event:
<input type="text" ... v-model="myinputbox" #compositionupdate="compositionUpdate($event)">
......
......
methods: {
compositionUpdate: function(event)
{
this.myinputbox = event.data;
},
}
Ok, I dont know if there is another solution for this issue, but it can be solved with a simple directive:
Vue.directive('$model', {
bind: function (el, binding, vnode) {
el.oninput = () => (vnode.context[binding.expression] = el.value)
}
})
using it just like
<input v-$model="{toBind}">
There is an issue on the oficial repo, and they say this is the normal behavior (because the composition mode), but I still need the functionality
EDIT: A simpler solution for me was to just use #input.native. Also, the this event has (now?) a isComposing attribute which we can use to either take $event.data into account, or $event.target.value
In my case, the only scheme that worked was handling #keydown to save the value before the user action, and handling #keyup to process the event if the value had changed. NOTE: the disadvantage of this is that any non-keyboard input (like copy/paste with a mouse) will not work.
<md-input
v-else
:value="myValue"
ref="input"
#keydown="keyDownValue = $event.target.value"
#keyup="handleKeyUp($event)"
#blur="handleBlur()"
/>
With handleKeyUp in my case being:
handleKeyUp(evt){
if(evt.target.value !== this.keyDownValue){
this.$emit('edited', evt);
}
}
My use case was the following:
I requested a search endpoint in the backend to get suggestions as the user typed. Solutions like handling #compositionupdate lead to sending several several requests to the backend (I also needed #input for non-mobile devices). I reduced the number of requests sent by correctly handling #compositionStarted, but there was still cases where 2 requests were sent for just 1 character typed (when composition was left then, e.g. with space character, then re-entered, e.g. with backspace character).
I have an array of strings bound to input elements:
<div repeat.for="i of messages.length">
<input type="text" value.bind="$parent.messages[i]">
</div>
I need to delete an element when the input content is deleted, without using dirty-checking.
This sounds easy - just delete the element which has empty value from the input.delegate handler, unfortunately this does not work due to an Aurelia bug #527. Here's a gist that tries this approach: https://gist.run/?id=e49828b236d979450ce54f0006d0fa0a
I tried to work around the bug by using queueTask to postpone deleting the array element, to no avail. And since the devs closed the bug because according to them it is a duplicate of a completely unrelated issue I guess it is not getting fixed anytime soon.
I am out of ideas how to implement this, so any suggestions are welcome.
Absolutely no need for any kind of dirty checking here! :)
Here's a working demo for your scenario: https://gist.run/?id=20d92afa1dd360614147fd381931cb17
$parent isn't needed anymore. It was related to pre-1.0 Aurelia versions.
If you use a variable instead of array indexes, you can leverage two-way data-binding provided by the input.
<template>
<div repeat.for="msg of messages">
<input type="text" value.bind="msg" input.delegate="onMessageChanged(msg, $index)">
</div>
</template>
So, your onChange event could be simplified like this:
msg holds the actual value of your current input.
i index will be used for deletion.
export class App {
messages = ['Alpha','Bravo','Charlie','Delta','Echo'];
onMessageChanged(msg, i){
if (!msg || msg.length === 0) {
this.messages.splice(i, 1);
}
}
}
There was a related question about a similar problem. This answer might give you more details about the main idea.
Ok, so the solution to this is not to use the buggy (in this case) aurelia 2-way binding, but to use 1-way binding and set the value from the input.delegate handler:
https://gist.run/?id=2323c09ec9da989eed21534f177bf5a8
The #marton answer seems to work at first sight, but it actually disables 2-way binding, so any changes to the inputs are not copied to the array. But it gave me an important hint how to solve the issue.
The equivalent of this html code:
<div repeat.for="msg of messages">
<input type="text" value.bind="msg">
</div>
is this:
for (let msg of messages) {
msg = 'something else'; // note: this does not change the contents of the array
}
See issue #444 for more details
Hence, this forces one-way binding. To fix this in the #marton solution, we only have to change the value from the input.delegate handler:
onMessageChanged(msg, i){
if (!msg || msg.length === 0) {
this.messages.splice(i, 1);//delete the element
}
else {
this.messages[i] = msg;//change the value
}
}