I'm using Rivets.js to draw some components within an rv-each-* block
They all render fine when the page loads.
When I Splice the first element of the model, the model correctly removes the first element but the rv-each-* block removes the last element.
The component is just made up of a button that contains the text of the objects value it is bound to. Next to each component call I print some text that is also bound to each objects value. The two should be the same, but after the Splice they are not.
var model2 = [{ "value":"1"},{"value":"2"},{"value":"3"}];
rivets.components['control'] = {
template: function() {
return '<button>{data.option.value}</button>';
},
initialize: function(el, attributes) {
return new controlviewmodel(attributes);
}
};
function doSplice()
{
model2.splice(0,1);
}
<table id="view">
<tr rv-each-option="model">
<td>
<control option="option"/>
</td>
<td>{option.value}</td>
</tr>
</table>
I've created a fiddle to try and show my problem: http://jsfiddle.net/dko9b9k4/
Am I doing something wrong or is this a bug?
Edit: this example can be fixed by changing
return new controlviewmodel(attributes);
to return attributes;
Related
I have deferred updates enabled.
I have two components.
The first is a list, which is simply implemented as a div with a foreach data binding:
<div class="list-people" data-bind="foreach: { data: people, afterRender: afterRenderPeople }">
<!-- ko component: { name: "listitem-person", params: { person: $data } } --><!-- /ko -->
</div>
The second is the list item:
<div class="listitem-person">
<span data-bind="text: Name"></span>
</div>
afterRender is called for each item in the foreach.
My afterRenderPerson function is simple enough:
public afterRenderPerson = (elements: any[], data: Person) => {
let top = $(element[0]).offset().top;
scrollTo(top);
};
The problem is that when afterRenderPerson is called the sub-component listitem-person hasn't yet been rendered.
Which means the element array passed to afterRenderPerson has 4 nodes:
A text node containing \n i.e. a new line.
A comment node containing <!-- ko component: { name: "listitem-person", params: { person: $data } } -->.
A comment node containing <!-- /ko -->.
A text node containing \n i.e. a new line.
None of these are suitable for getting the top pixel, and even if they were, the sub-component being rendered could affect the layout at that location changing the value of the pixel I'm trying to get.
Unfortunately it seems that the documentation for foreach doesn't take in to account the delayed nature of components.
If you need to run some further custom logic on the generated DOM elements, you can use any of the afterRender/afterAdd/beforeRemove/beforeMove/afterMove callbacks described below.
Note: These callbacks are only intended for triggering animations related to changes in a list.
There are two workarounds I've come across, neither of which are great, but that's why they're workarounds and not solutions!
user3297291 gave the suggestion in a comment of making a scrollTo binding that's placed on the child components.
Only workaround I can think of is to define a custom scrollTo binding and include it in the component template... Quite easy to implement, but still feels hacky and makes your inner component harder to reuse. You might also want to track this feature request – user3297291
This would simply be a custom binding that conditionally executes some code based on a value provided to it.
The bindings aren't called until the HTML has been inserted in to the DOM. That's not perfect, as later changes to the DOM could affect the position of the inserted HTML elements, but it should work for many situations.
I wasn't very keen on having to modify the child components though, I preferred a solution when remained encapsulated in the parent component.
The second workaround is to check to see if the child component HTML element exists in the DOM by it's ID. Since I don't know when they will come in to existence this has to be done in some sort of loop.
A while loop isn't suitable as it'll run the check far too often, in a "tight" loop, so instead setTimeout is used.
setTimeout is a horrid hack, and it makes me feel dirty to use it, but it does work for this situation.
private _scrollToOffset = -100;
private _detectScrollToDelayInMS = 200;
private _detectScrollToCountMax = 40;
private _detectScrollToCount = 0;
private _detectScrollTo = (scrollToContainerSelector: string, scrollToChildSelector: string) => {
//AJ: If we've tried too many times then give up.
if (this._detectScrollToCount >= this._detectScrollToCountMax)
return;
setTimeout(() => {
let foundElements = $(scrollToChildSelector);
if (foundElements.length > 0) {
//AJ: Scroll to it
$(scrollToContainerSelector).animate({ scrollTop: foundElements.offset().top + this._scrollToOffset });
//AJ: Give it a highlight
foundElements.addClass("highlight");
} else {
//AJ: Try again
this._detectScrollTo(scrollToContainerSelector, scrollToChildSelector);
}
}, this._detectScrollToDelayInMS);
this._detectScrollToCount++;
};
I made sure to put a limit on how long it can run for, so if something goes wrong it won't loop forever.
It should probably be noted that there is an "Ultimate" solution to this problem, and that's TKO, AKA Knockout 4.
But that's not "production ready" yet.
How to know when a component has finished updating DOM?
brianmhunt commented on Jun 20
knockout/tko (ko 4 candidate) latest master branch has this.
More specifically, the applyBindings family of functions now return a Promise that resolves when sub-children (including asynchronous ones) are bound.
The API isn't set or documented yet, but the bones have been set up.
This appears to work. I made a binding handler that runs a callback in its init (it uses tasks.schedule to allow a rendering cycle). Attaching it at the parent level does not get the children rendered in time, but attaching it to the virtual element does.
I designed it to work with a function whose signature is like afterRender. Because it runs for each of the elements, the callback function has to test that the data is for the first one of them.
ko.options.deferUpdates = true;
ko.bindingHandlers.notify = {
init: function (element, valueAccessor, allBindings, viewModel, bindingContext) {
// Make it asynchronous, to allow Knockout to render the child component
ko.tasks.schedule(() => {
const onMounted = valueAccessor().onMounted;
const data = valueAccessor().data;
const elements = [];
// Collect the real DOM nodes (ones with a tagName)
for(let child=ko.virtualElements.firstChild(element);
child;
child=ko.virtualElements.nextSibling(child)) {
if (child.tagName) { elements.push(child); }
}
onMounted(elements, data);
});
}
};
ko.virtualElements.allowedBindings.notify = true;
function ParentVM(params) {
this.people = params.people;
this.afterRenderPeople = (elements, data) => {
console.log("Elements:", elements.map(e => e.tagName));
if (data === this.people[0]) {
console.log("Scroll to", elements[0].outerHTML);
//let top = $(element[0]).offset().top;
//scrollTo(top);
}
};
}
ko.components.register('parent-component', {
viewModel: ParentVM,
template: {
element: 'parent-template'
}
});
function ChildVM(params) {
this.Name = params.person;
}
ko.components.register('listitem-person', {
viewModel: ChildVM,
template: {
element: 'child-template'
}
});
vm = {
names: ['One', 'Two', 'Three']
};
ko.applyBindings(vm);
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.4.2/knockout-min.js"></script>
<template id="parent-template">
<div class="list-people" data-bind="foreach: people">
<!-- ko component: { name: "listitem-person", params: { person: $data } }, notify: {onMounted: $parent.afterRenderPeople, data: $data} -->
<!-- /ko -->
</div>
</template>
<template id="child-template">
<div class="listitem-person">
<span data-bind="text: Name"></span>
</div>
</template>
<parent-component params="{ people: names }">
</parent-component>
I'm new in React, but I have some experience in JS.
My question is:
I have a function and I put this functions to onMouseOver event to element
<td> in current situation.
I want to get this current dom element and get index of this element next.
My code is bellow:
var Cell = function(k) {
function getIndex(cell){
console.log(cell)
}
return (
<td key ={k} onMouseOver={function() {getIndex(this)}}>
<div className="square__cell" ></div>
</td>
)
}
In js it works something like this. But now in React it returns me null.
If I put in console.log "1" for example it also works. So function is woks and I have only problem to get information about current element
Please help to find out how to do it.
Thanks.
You have to bind the function instead of creating new function so the context scope of component remains same
var Cell = function(k) {
function getIndex(cell){
console.log(cell)
}
return (
<td key ={k} onMouseOver={this.getIndex.bind(this,k)}}>
<div className="square__cell" ></div>
</td>
)
}
I'm trying to implement a form where I can delete specific inputs using React. The problem is, react doesn't seem to be rendering the information correctly. This is my render function:
render: function(){
var inputItems;
if (this.state.inputs){
inputItems = this.state.inputs.map(function(input){
console.log(input)
return (
<Input
input={input}
onDestroy={this.destroy.bind(this, input)}
onEdit={this.edit.bind(this, input)}
editing={this.state.editing === input.id}
onCancel={this.cancel} />
);
}, this);
}
(...)
// this isn't the actual render return
return {inputItems}
and my destroy function:
destroy: function (input) {
var newInputs = this.state.inputs.filter(function (candidate) {
return candidate.id !== input.id;
});
this.setState({
inputs: newInputs
});
},
The actual destroy function is getting called through a child component via <a href="#" onClick={this.props.onDestroy}>(Remove)</a>. The interesting thing is that when I console log my inputs, as seen in the render function, the correct inputs are shown - the one I called the destroy function on is gone. But the incorrect inputs are rendered - it's always the very last one that disappears, not the one I called the destroy function on. So for example, I'll initially log:
First Name
Last Name
Email
and call the destroy function on the Last Name. The console.log will show:
First Name
Email
but the actual rendered information will show:
First Name
Last Name
Thanks!
Figured it out. Has to do with React child reconciliation. Added a key={input.id} to the <Input> tag and it works.
More information here under child reconciliation and dynamic children.
http://facebook.github.io/react/docs/multiple-components.html
In a basic table structure, I want to be able to display a set of data from an array of objects one at a time. Clicking on a button or something similar would display the next object in the array.
The trick is, I don't want to use the visible tag and just hide the extra data.
simply you can just specify property that indicate the current element you want to display and index of that element inside your observableArray .. i have made simple demo check it out.
<div id="persons"> <span data-bind="text: selectedPerson().name"></span>
<br/>
<button data-bind="click: showNext" id="btnShowNext">Show Next</button>
<br/>
</div>
//here is the JS code
function ViewModel() {
people = ko.observableArray([{
name: "Bungle"
}, {
name: "George"
}, {
name: "Zippy"
}]);
showNext = function (person) {
selectedIndex(selectedIndex() + 1);
};
selectedIndex = ko.observable(0);
selectedPerson = ko.computed(function () {
return people()[selectedIndex()];
});
}
ko.applyBindings(new ViewModel());
kindly check this jsfiddle
Create observable property for a single object, then when clicking next just set that property to other object and UI will be updated.
This is my view for a single row as "tr". I want want to click on the name cell and pop up a view for that cell. I could not get the event firing..
am I missing something? Thanks!
So this issue is solved by gumballhead, the issue I was having is that there needs to be a tagName associated with the ItemRowView. and then in the render function, I need to do self.$el.html(this.template(model));
Thought it might be helpful to share with..
ItemRowView = Backbone.View.extend({
initialize : function() {
},
template : _.template($('#item-row-template').html()),
render : function() {
var self=this;
var model = this.model.toJSON();
self.$el = this.template(model);
return self.$el;
},
events : {
"click td .item-name" : "viewOneItem"
//Even if I change it to "click td":"viewOneItem", still not firing
},
viewOneItem : function() {
console.log("click");
}
});
collection View:
ItemsView = Backbone.View.extend({
initialize : function() {
},
tagName : "tbody",
render : function() {
var self = this;
this.collection.each(function(i) {
var itemRowView = new ItemRowView({
model : i
});
self.$el.append(itemRowView.render());
});
return self.$el;
}
});
app view:
AppView = Backbone.View.extend({
this.items = new Items();
this.items.fetch();
this.itemsView = new ItemsView({collection:this.items});
$('#items-tbody').html(itemsView.render());
});
for template:
<script type="text/template" id="item-row-template">
<tr>
<td class="item-name">{{name}}</td>
<td>{{description}}</td>
</tr>
</script>
<table>
<thead>
<tr>
<th>name</th>
</tr>
</thead>
<tbody id="items-tbody">
</tbody>
</table>
Use "click td.item-name" for your selector. You are currently listening for clicks on a descendant of td with the class "item-name".
FYI, you've also got a closing tag for an anchor element without an opening tag in your template.
Edit: I think you want self.$el.html(this.template(model)); rather than self.$el = this.template(model);
But there's no need to alias this to self with the code you posted.
Edit 2: Glad you got it sorted out. Let me give you an explanation.
All Backbone Views need a root element. That's the element that the events in the events hash are delegated to on instantiation. When a Backbone View is instantiated without an existing element, it will create one based on configuration settings like tagName, whose default is "div". The element won't appear in the DOM until you explicitly inject it.
So when you set self.$el in your render method, you were overwriting the root element (along with the events, though they would have never fired because it would have listened for a click on a td that was a descendant of a div that didn't exist in the DOM).
As a side note, and it would not be the right way to do it in your case, you could have done this.setElement($(this.template(model)); to redelegate the events from the div created on instantation to the tr created by your original template.