I am trying to bind to data below which is a dictionary
<template is="dom-repeat" items="{{data}}">
</template>
I have found a similar question here Polymer: How to loop and render HTML to screen
<template repeat="{{customer, i in customers}}">
<div>{{i}}, {{customer.name}}</div>
</template>
but I am not sure if this applies to Polymer 1.0 and cannot find anything in the doc.
How do I do this in 1.0?
Cheers
What you have in the first example is correct for Polymer 1.0. Here is the documentation for the template repeat (dom-repeat).
<template is="dom-repeat" items="{{data}}">
<div>
<span>{{index}}</span> <span>{{item}}</span>
</div>
</template>
Related
I have a polymer 1 application that used paper-menu and paper-submenu. I am rewriting it in Polymer 3. What is the general consensus for its replacement? I have searched for this and have found nothing. It would be good if the documentation for paper-menu and paper-submenu showed its replacement.
You can refer MWC-Menu for polymer 3 support link here
I replaced paper-menu and paper-submenu with the Polymer 3 elements vaadin-accordion and paper-listbox
<vaadin-accordion>
<template is="dom-repeat" items="{{sources}}">
<vaadin-accordion-panel theme="filled">
<div slot="summary">[[item.name]]</div>
<paper-listbox>
<template is="dom-repeat" items="{{item.models}}">
<paper-item on-tap="selectModel">[[item.name]]</paper-item>
</template>
</paper-listbox>
</vaadin-accordion-panel>
</template>
</vaadin-accordion>
I'm looking for a better optimized solution to have too many if's in Polymer 2.0. For example i'm building a table object, where each cell can be text, buttons, links, objects, ect. I want the user to be able to enter a 2D array and have the Polymer 2.0 object be able to pick which markup to use. My current solution (below) simple has several if statements, but this means that every cell if going to call each statement. Is there a a better way to handle this?
<template is="dom-if" if="[[matchCellType(cell, 'button')]]">
<UI-Button id='[[cell.button.ID]]' class$='[[cell.button.class]]'>[[cell.button.text]]</UI-Button>
</template>
<template is="dom-if" if="[[matchCellType(cell, 'object')]]">
<span class="object-toggle"></span>[[cell.title]]
<div class="properties">
<template is="dom-repeat" items="[[getProps(cell)]]">
<div class="properties_row"><div class="properties_cell"><b>[[item.title]]:</b></div><div style="display: table-cell">[[item.val]]</div></div>
</template>
</div>
</template>
<template is="dom-if" if="[[matchCellType(cell, 'link')]]">
<a target="_blank" href='[[cell.link.href]]'>[[cell.link.text]]</a>
</template>
<template is="dom-if" if="[[matchCellType(cell, 'cell')]]">
[[cell]]
</template>
<template is="dom-if" if="[[matchCellType(cell, 'textArea')]]">
<ui-text-area rows="[[cell.textArea.rows]]" cols="[[cell.textArea.cols]]" id='[[cell.textArea.id]]' class$='[[cell.textArea.class]]' text= [[cell.textArea.text]]></ui-text-area>
</template>
Lots of calls to matchCellType don't harm if it isn't a costly computation (if it were, you could update a property in an observer and test on the property instead)
Factor out the series of ifs into a component so you don't clutter up your table
As an alternative to using dom-ifs, compute an attribute or style class from the cell, render all elements always, and use CSS to have only the matching elements be visible. This produces much more DOM elements, but may still be more performant because browsers handle hidden or display:none elements very efficiently
Instead of stamping with several dom-ifs, you could create and remove nodes imperatively
Is it possible to have multiple slots in a custom component?
i.e.
<template>
<slot id="first"></slot>
<slot id="second"></slot>
</template>
Yes, but you should use name instead of id.
<template>
<div>
The first slot:
<div>
<slot name="slot1"></slot>
</div>
The second slot:
<div>
<slot name="slot2"></slot>
</div>
</div>
</template>
It's documented here for now: http://blog.durandal.io/2016/05/23/aurelia-shadow-dom-v1-slots-prerelease/ I'll be adding this to the content projection section of the Custom Elements documentation soon.
I'm using a conditional template to distribute content that is passed into the element. If the condition is true, it will show the first content element, otherwise the second. I noticed that when I update the condition the already distributed content is not updated. Once it is visible it will remain visible.
My first attempt looked like this:
<template is="dom-if" if="{{test}}">
<content select=".first">
</content>
</template>
<template is="dom-if" if="{{!test}}">
<content select=".second">
</content>
</template>
I noticed that it will work, if the content is wrapped in another element.
<template is="dom-if" if="{{test}}">
<div>
<content select=".first">
</content>
</div>
</template>
<template is="dom-if" if="{{!test}}">
<div>
<content select=".second">
</content>
</div>
</template>
I've created a plunker that demonstrates both cases.
Is there an explanation for this behaviour? Is it on purpose or a bug?
This is actually per design. Here`s what the Polymer team had to say on the issue on Github.
Hiding a <content> has no effect on the visibility of its distributed children (per spec), so your options are to wrap the content with a wrapper element that can be hidden (and will hide the distributed children), or use restamp which will pull the <content> out of the DOM all together.
It is slightly unintuitive that the restamp and non-restamp setups work differently, however it is a result of the non-restamp behavior which hides rather than destroying DOM as a performance optimization.
I'm using Polymer Starter Kit as a base for an app.
So, this is a single page app with routing to specific section.
My index is basically unchanged, you can see it here https://github.com/PolymerElements/polymer-starter-kit/blob/master/app/index.html.
Now I have my custom element here
<dom-module id="lista-contatti">
<template>
<iron-ajax url="../../api/get_contacts.php" last-response="{{data}}" auto></iron-ajax>
<iron-list items="{{data}}" as="item" id="list">
<template>
<paper-icon-item>
<avatar class$="[[item.classe]]" item-icon></avatar>
<paper-item-body two-line>
<div><span>[[item.nome]]</span> <span>[[item.cognome]]</span></div>
<div secondary><span>[[item.tipo]]</span></div>
</paper-item-body>
</paper-icon-item>
</template>
</iron-list>
</template>
</dom-module>
This works because if I give a fit class to my iron-list I can see my list populating. The only problem is that my list will render under my main app header (and that makes sense because of the fit layout given to my list).
Also, the list works great with header if I put it on a single html file, as you can see in iron-list official demo pages.
Now I want to keep my list in an external dom-module, but I need it to work seamlessly with other elements of the page in the single page app scenario of the polymer starter kit.
EDIT: this is my index.html one page app layout
<body>
<template is="dom-bind" id="app">
<paper-drawer-panel>
<paper-scroll-header-panel drawer fixed>
<paper-toolbar> ... </paper-toolbar>
<paper-menu> ... </paper-menu>
</paper-scroll-header-panel>
<paper-scroll-header-panel main condenses keep-condensed-header>
<paper-toolbar> ... </paper-toolbar>
<iron-pages attr-for-selected="data-route" selected="{{route}}">
<section data-route="foo"> ... </section>
<section data-route="contact">
<!-- HERE IS MY DOM-MODULE -->
<lista-contatti></lista-contatti>
</section>
</iron-pages>
</paper-scroll-header-panel>
</paper-drawer-panel>
</template>
</body>
My iron-list does not work as expected with paper-scroll-header-panel because it is nested inside many elements like iron-pages, section and my custom dom-module. The list can't interact with the header height and doesn't scroll seamlessly with it.
In earlier versions of polymer you had to bind your list's scrollTarget to header panel's scroller. There is a slide about this in a Polymer 0.5 video #11:58. In which case the updated code in Polymer 1.0 might look something like:
<paper-scroll-header-panel id="hPanel" main condenses keep-condensed-header>
<iron-list id="list" items="{{data}}" as="item" >
...
</iron-list>
</paper-scroll-header-panel>
script:
document.querySelector("#list").scrollTarget = document.querySelector("#hPanel").scroller;
NB: I haven't tested this yet but figured it might help to point you in the right direction for now.