Is it possible to conditionally add an attribute to an element using binding syntax? I am aware of if.bind, but that targets elements. Rather I am interested in targeting a specific attribute on an element.
Example:
<a href.bind="model.link">${model.text}</a>
If model.link is falsy, then I don't want the href at all--just treat the <a /> as a container element.
I realize I could create two <a /> tags--one with the attribute and one without--and use an if.bind on both, but that seem clunky and un-aurelia like.
I don't think it's supported in Aurelia currently (issue 1, issue 2)
This,
<a href.bind="addLink ? link : ''">Link</a>.
will produce
<a href>Link</a>
if addLink is false.
It won't remove the attribute entirely. If you are using a library which will check the existence of an attribute to manipulate the element, then this won't work. Another option would be to create a custom attribute like this. But that seems like an overhead.
Related
I am writing a custom TagHelper that should change its behavior based on what child elements its owner tag has. This will be used for substituting custom html elements in a localized string.
Here's a simple example of what I'm trying to do:
<h2 locale-key="Hello, %1!">
<span class="bold" locale-parameter="1">#userName</span>
</h2>
In the example above, the TagHelper for LocaleKey will change the content of the <h2> tag to a localized string. If this is a simple string with no parameters, then I can just simply use output.Content.SetHtmlContent() in the TagHelper to set the h2's content to the string. However in this case, the localized string has a parameter (%1), and I want the corresponding child element (<span parameter="1">) to be substituted in the final output. So the final rendered html would look like this:
<h2>Hello, <span class="bold">Lázár Zsolt</span>!<h2/>
To achieve this, I should be able to see all the child elements in the DOM from the LocaleKey TagHelper, so I can generate the correct HTML code. In the TagHelper's ProcessAsync method I can access the TagHelperContext and the TagHelperOutput, but I couldn't find any information about child elements in either of these objects while debugging. Is this possible somehow?
Another approach is to leave the string as is, with the %1 parameter key, and then use the child ParameterTagHelper to substitute itself into the parameterized string. To do this, I'd have to see the siblings of the current tag from the TagHelper.
Recursion would also be fun (e.g. the <span> is also localized and has its own parameters), but for the scope of this question, I'd be happy if I could get this to work without recursion.
I posted too soon again... There is a GetChildContentAsync() method in TagHelperOutput that will... get the child content asynchronously.
Hi I'm trying to figure out how to use v-if on a iterated element which also uses v-for. I need to check if the current element has any of a series of classes, which are numbers.
so the classes of each article would be:
<article class="post-item post-guide 12 22 19 30 55">...
this is the HTML that renders all:
<article v-if="showIfHasClass" :class="'post-item post-guide ' + guide.categories.toString().replace(/,/g, ' ')"
v-for="(guide, index) in guides" :key="index">
<header>
<h1 class="post-title">
{{ guide.title.rendered}}
</h1>
</header>
</article>
I have tried with methods that check the class of all elements, that works, but i'm trying to use a clean Vue built-in solution with v-if without success, i'm not able to retrieve the class of this in a successful way.
Should showIfHasClass be a computed property? I have tried with that too... but it seems, I'm missing something along the way.
my data I have to check against is an array:
data:{
guides: [...]
selectedCategories: [1, 22, 33, 100, 30];
}
or maybe it is better to directly loop over the guides and check if they have the selectedCategory or not, then remove the element from the guides data array?
What is more effective?
Besides the option to create an additional filtered computed (effectively eliminating the need to use v-for and v-if on the same element), you also have a template level way of dealing with such edge-cases: the <template> tag.
The <template> tag allows you to use arbitrary template logic without actually rendering an extra element. Just remember that, because it doesn't render any element, you have to place the keys from the v-for on the actual elements, like this:
<template v-for="(guide, index) in guides">
<article v-if="isGuideVisible(guide)"
:key="index"
class="post-item post-guide"
:class="[guide.categories.toString().replace(/,/g, ' ')]">
<header>
<h1 v-text="guide.title.rendered" />
</header>
</article>
</template>
isGuideVisible should be a method returning whether the item is rendered, so you don't have to write that logic inside your markup. One advantage of this method is that you can follow your v-if element with a fallback v-else element, should you want to replace the missing items with fallback content. Just remember to also :key="index" the fallback element as well.
Apart from the above use-case, <template> tags come in handy when rendering additional wrapper elements is not an option (would result in invalid HTML markup) (i.e: table > tr > td relations or ol/ul > li relations).
It's mentioned here as "invisible wrapper", but it doesn't have a dedicated section in the docs.
Side note: since you haven't actually shown what's inside guide.categories, I can't advise on it, but there's probably a cleaner way to deal with it than .toString().replace(). If guide.categories is an array of strings, you could simply go: :class="guide.categories".
I think the most Vue way is to create a computed property with filtered items from selected categories, then use that in v-for loop (the idea is to move the business logic away from template).
computed: {
filteredItems(){
return this.guides.filter(e => this.selectedCategories.includes(e.category))
}
}
Also, as a note, it is not recommended to use v-if and v-for on the same element, as it may interfere with the rendering and ordering of loop elements. If you don't want to add another level of nesting, you can loop on a 'template' element.
<template v-for="item in items">
// Note the key is defined on real element, and not on template
<item-element v-if='condition' :key="item.key"></item-element>
</template>
Consider this xpath which should always return one element.
//div[#id='MyDiv123']/div[contains(#class, 'super')]
Assume that we won't add anymore divs whose class is super. Given that info, I don't think that it is a good idea to use /div[contains(#class, 'super')]because the xpath will break if div[contains(#class, 'super')] is placed inside another element.
Shouldn't we be using //div[contains(#class, 'super')] instead ?
I don't like using XPaths for locators that can be written as a CSS selector. I think it's much simpler as
#MyDiv123 > div.super
or just
div.super
if it's unique on the page.
XPath contains() is a string match. All the elements below will match your XPath locator but none of them will match the CSS selectors above.
<div class="super-duper" ...>
<div class="superior" ...>
<div class="abcsuperdef" ...>
... you get the idea...
There is no defined Best Practices while writing xpaths. It all boils down to how effective xpath can be written.
I don't see any issue with the xpath as :
//div[#id='MyDiv123']/div[contains(#class, 'super')]
Of-coarse there ca be some improvements as follows :
As an enduser you won't be sure how the class attribute super impacts the HTML or which elements have this attribute. So in that case to identify the WebElement uniquely it would be wise to include the ancestor <div> tag with id as MyDiv123.
But it doesn't looks like the classname super can be dynamic. Hence you can avoid the keyword contains within the xpath and rewrite it as :
//div[#id='MyDiv123']/div[#class='super']
Is there any reason why a repeat.for binding would remove attributes from elements inside the repeater?
<div repeat.for="i of model.someArray.length">
<label>Some Array - Index ${i + 1}</label>
<input value.bind="model.someArray[i]" some-custom-attribute="someArray[${i}]"/>
</div>
and that some-custom-attribute is not being output within the repeat, but if I were to remove the string interpolation within there then it outputs fine.
== Edit ==
I have put it in a comment but just to make sure everyone is on the same page, ideally this is the output I expect:
<input value.bind="model.someArray[i]" some-custom-attribute="someArray[0]"/>
The some-custom-attribute is not an aurelia attribute, its pure HTML that a 3rd party JS library uses, so the goal here is to get the textual value of the index into the textual attribute value.
model.someArray.length is a number, not an array. You need to iterate over the array. If you do need the current index, the repeater provides the $index property for you to use.
Your code should look like this:
<div repeat.for="item of model.someArray">
<label>Some Array - Index ${$index + 1}</label>
<input value.bind="item" some-custom-attribute.bind="item"/>
</div>
To answer your original question, doing some-custom-attribute="model.someArray[${i}]" makes Aurelia think you are trying to pass a string value to the custom attribute. You can see that in the following gist: https://gist.run/?id=eed8ac8623ff4749aa5bb93c82a7b1fb I've created a custom element that just pushes whatever value it is given in to an element on the page. Note!!! Don't ever do what I'm doing here! I just did this this way so you wouldn't have to open the js console. To actually get a value passed in, you would need to use some-custom-attribute.bind="item" or (to do things how you are doing things, some-custom-attribute.bind="someArray[i]"
I am trying to automate test case using Protractor and Jasmine. The problem is I have an "article" web element tag that gets created at runtime and this web-element has a as sub element. This div element has a "id" tag associated with it. The structure of the code is below.
<article class="a b c d" data-ng-repeat="xyz repeat">
<div id="THIS IS WHAT I WANT" class="class name">
</article>
Now I am able to get get hold of the article web-element. but I am not able to get the ID attribute in the div. The ID values is generated dynamically. Kindly suggest how I can get the ID value.
Thank you
You can use a CSS Selector like this:
article > div
This will get you a div inside of an article. Now you can use this to play around and specify the selector further with classes or other stuff.
If you managed to get the div element you can then pull out the idea using (not sure if the syntax is correct but you should get the idea):
element.getAttribute('id')
1) element(by.xpath(//div[#class='class name'])).getAttribute('id')
2) element(by.xpath(//article [#class='abcd']//div[#id='THIS IS WHAT I WANT'])).getAttribute('id')
You can use chains like this:
element(by.classname('')).element(by.className('classname'));
or
element(by.css('css of parent')).element(by.css('child css'));
or you can use element(by.repeater('repeat in reapeats')).element(by.css(''));