I have put together a custom element using Polymer - <x-flickr> (http://tamas.io/x-flickr-custom-polymer-element/ || https://github.com/tamaspiros/x-flickr) - it essentially makes a REST call to the Flickr API and returns photos based on a search:
<polymer-jsonp id="ajax" auto url="http://api.flickr.com/services/rest/?method=flickr.photos.search&api_key={{apikey}}&tags={{tag}}&per_page={{amount}}&page=1&format=json&jsoncallback="></polymer-jsonp>
This call returns some information about a particular photo but not everything. I'd like to reuse the unique ID returned via this call and make a second REST call to get further detail about the image. At the moment I display the photos via:
<template id="photos" repeat="{{photo in photos}}">
<div class="thumbnail">
<img src="http://farm{{photo.farm}}.staticflickr.com/{{photo.server}}/{{photo.id}}_{{photo.secret}}.jpg" class="img-thumbnail">
</div>
</template>
but I'd like to extend that so that I get the description of the photo as well (and this is the information that is not being returned by the first REST call displayed above) - so my template would look something like this:
<template id="photos" repeat="{{photo in photos}}">
<div class="thumbnail">
<img src="http://farm{{photo.farm}}.staticflickr.com/{{photo.server}}/{{photo.id}}_{{photo.secret}}.jpg" class="img-thumbnail">
<p>{{photo.description}}</p> <!-- this should come from the 2nd API call -->
</div>
</template>
What's the best way of achieving this?
I forked your project so you can see the details of what I'm about to describe here https://github.com/sjmiles/x-flickr.
The short answer to your question is to include a request element (polymer-ajax) inside the template repeat. That causes a request to spawn for each item in the repeat, and gives you easy access to the item data (the photo id in this case).
As I mentioned, you can see an example of how this can be done in the source here: https://github.com/sjmiles/x-flickr/blob/master/x-flickr.html#L46.
A few other notes:
You don't need JSONP for these requests, simple Ajax calls will do, you can access the JSON directly. I used polymer-ajax instead of polymer-jsonp.
You almost never need addEventListener in Polymer because you can listen to events using on-<eventName>="methodName" syntax directly in the HTML. In this case, you don't need to use events at all, because you can do the work with data binding.
This could be done completely script-free, but I kept your script for setting photos property and sending the x-flickr-load event.
HTH
One way to tackle this: http://jsbin.com/yihovepi/1/edit (also includes some refactoring)
The <p>{{photo.description}}</p> is always in the template, but the .description is filled later by dynamically creating <polymer-jsonp> for each photo.
Note, I'm also using binding to the main polymer-jsonp element's response property:
<polymer-jsonp id="ajax" response="{{response}}">
This is super changed because the corresponding responseChanged() callback is called when that value is populated from the request.
Related
I'm new to Angular and I just put in place an i18n (2 languages) system for a website I am creating. Everything works properly but in order to switch from one language to another in my header, I feel stuck.
I followed the Angular documentation to transfer my variables from child to parent component and I ended with this:
<input type="text" id="item-input" #lang>
<button type="button" (click)="changeChosenLang(lang.value)">
{{ 'global.lang' | translate }}
</button>
As you can see, I write my language in the input form and I send it to the proper component with a button. What I wanted was to click on my 'global.lang' text and to be able to send its value to the parent component, since the value is the language which is not actually used.
I don't know how to put my 'global.lang' text in a variable, neither what kind of balise I can use. Also I didn't know how to summarize my problem to search for it on StackOverflow so if you know a similar post, don't hesitate to post the link.
Thank you for your reading!
I found a less tortured way (poor brain) to have the result I wanted:
<span (click)="changeChosenLang()">
{{ 'global.lang' | translate }}
</span>
First I temporary changed my button to a span balise and I deleted the parameter from my changeChosenLang() function. Then, I transferred a variable 'lang' from my parent component to this one, witch contains the value of the language chosen in my app constructor. At each click, I change its value in my changeChosenLang() function and everything works great!
I hope it can help someone someday. The moral of this post is: the simpler, the better! Have a good day.
In some instances, I need to just repeat some html code within my Template to DRY it up, but making a new component and passing a ton of props and dynamic data to it seems like overkill. Is there a way to define a repeatable block of template code that can just be reused?
A good example of this is my vuelidate validation error messages that are repeated. I don't want to create an entire vue component for them because then I need to pass in the validation, validation prop and a few other things so that seems like creating more complexity just to DRY up a little bit of the template.
I have this block of code on three different scenarious in the same template, is there a way I can just define them as a block to reuse. Literally nothing changes so it's very much against DRY principles.
<span
v-if="!$v.initialReplyText.required"
class="error">Your reply cannot be empty.</span>
<span
v-if="!$v.initialReplyText.maxLength"
class="error">Your reply cannot be over 2,000 characters.</span>
you can do dynamic binding using v-bind, that way you don't need to bind all properties individually.
<!-- pass down parent props in common with a child component -->
<child-component v-bind="$props"></child-component>
src: https://v2.vuejs.org/v2/api/#v-bind
You can also use slots, or scoped slots, which are commonly used for things like wrapping error messages in more complex markup.
If all elements are consecutively arranged as in your example, you can use v-for as below:
<span v-for="(criteria, msg) in {'Your reply cannot be empty.': !$v.initialReplyText.required, 'Your reply cannot be over 2,000 characters.': !$v.initialReplyText.maxLength }"
v-if="criteria" class="error">
{{msg}}
</span>
I have a problem with the new ng-content transclusion.
Let's say I have a component my-component that, in its ngOnInit() function does some heavy operation on load (for now, just a console.log()).
I have a wrapper, that displays the content via transclusion (my-wrapper.component.html).
<ng-content></ng-content>
If I set the surroundings up like this, the log statement doesn't show:
<my-wrapper *ngIf="false">
<my-component></my-component>
</my-wrapper>
I assume, the my-wrapper component does not get built, so the content is ignored.
But if I try to move the logic into the my-wrapper component like this (my-wrapper.component.html):
<ng-container *ngIf="false">
<ng-content></ng-content>
</ng-container>
I always see the console.log() output. I guess, the my-component gets built and then stored away until the *ngIf becomes true inside my-wrapper.
The intention was to build a generic "list-item + detail" component. Say I have a list of N overview-elements (my-wrapper), that get rendered in a *ngFor loop. Every of those elements has its own detail component (my-component) that is supposed to load its own data, once I decide to show more infos to a specific item.
overview.html:
<ng-container *ngFor="let item of items">
<my-wrapper>
<my-component id="item.id"></my-component>
</my-wrapper>
</ng-container>
my-wrapper.component.html:
<div (click)="toggleDetail()">Click for more</div>
<div *ngIf="showDetail">
<ng-content></ng-content>
</div>
Is there a way to tell Angular, to ignore the transcluded content until it is necessary to be added to the page? Analogously to how it was in AngularJS.
Based on the comment of #nsinreal I found an answer. I find it to be a bit abstruse, so I'm trying to post it here:
The answer is to work with ng-template and *ngTemplateOutlet.
In the my-wrapper component, set up the template like this (my-wrapper.component.html):
<div (click)="toggleDetail()">Click for more</div>
<div *ngIf="showDetail" [hidden]="!isInitialized">
<ng-container *ngTemplateOutlet="detailRef"></ng-container>
</div>
Note, that the [hidden] there is not really necessary, it hides the "raw" template of the child until it decides it is done loading. Just make sure, not to put it in a *ngIf, otherwise the *ngTemplateOutlet will never get triggered, leading to nothing happening at all.
To set the detailRef, put this in the component code (my-wrapper.component.ts):
import { ContentChild, TemplateRef } from '#angular/core';
#Component({ ... })
export class MyWrapperComponent {
#ContentChild(TemplateRef) detailRef;
...
}
Now, you can use the wrapper like this:
<my-wrapper>
<ng-template>
<my-component></my-component>
</ng-template>
</my-wrapper>
I am not sure, why it needs such complicated "workarounds", when it used to be so easy to do this in AngularJS.
By doing this:
<my-wrapper *ngIf="false">
<my-component></my-component>
</my-wrapper>
You are not calling MyComponent component, because the *ngIf is false. that means, that not calling it you are not instancing it and, therefore, not passing through its ngOnInit. And that's why you are not getting the console log.
By doing this:
<ng-container *ngIf="false">
<ng-content></ng-content>
</ng-container>
You are inside the component, you are just limiting what to render in your template, but you already instanced your component and, therefore, you passed through your ngOnInit and you get your console log done.
If, you want to limit something (component call with selector or a ng-content or even a div) until you have some data available, you can do the following:
datasLoaded: Promise<boolean>;
this.getData().subscribe(
(data) => {
this.datasLoaded = Promise.resolve(true); // Setting the Promise as resolved after I have the needed data
}
);
And in your template:
<ng-container *ngIf="datasLoaded | async">
// stuff here
</ng-container>
Or:
<my-component *ngIf="datasLoaded | async">
// Didn't test this one, but should follow the same logic. If it doesn't, wrap it and add the ngIf to the wrapper
</my-component>
It’s because Ng content happens at the build time and when you pass the content it is actually not removed or recreated with the ngIf directive. It is only moved and the component is instantiated .
I encountered this problem recently as well but settled on a different solution than the currently accepted one.
Solution (TL;DR)
(Solution is for AngularDart; I figure it's similar in Angular though)
Use a structural directive; tutorials linked below.
Instead of:
<my-wrapper>
<my-contents></my-contents>
</my-wrapper>
your usage becomes:
<div *myWrapper>
<my-contents></my-contents>
</div>
which is shorthand for the following (in AngularDart; I think Angular uses <ng-template>)
<template myWrapper>
<div>
<my-contents></my-contents>
</div>
</template>
The MyWrapper directive logic is similar to NgIf except it has its own logic to compute the condition. Both of the following tutorials explain how to create an NgIf-like directive and how to pass it your own inputs using the special microsyntax (e.g. *myWrapper="myInput: expression"). Note that the microsyntax doesn't support outputs (#Output), but you can mimic an output by using an input that is a function.
Tutorial for Angular
Tutorial for AngularDart
Caveat: Since this is just a directive, it shouldn't do anything more complicated than instantiating a template ref at the appropriate time and maybe specifying some DI providers. For example, I would avoid trying to apply styles or instantiating a complex tree of components in the directive. If I wanted to create a list component, I would probably take the #ContentChild(TemplateRef) approach described in another answer; you would lose the asterisk shorthand for creating <template> but you would gain the full power of components.
My problem
My team owns an app that's part of a larger web application with other apps owned by other teams. Our components assume they can inject a MyAppConfiguration object, but this object can only be injected after it is loaded with an asynchronous request. In our app this is not a problem: we have a "shell" component that hides everything behind an ngIf until the configuration is loaded.
The problem is when other teams want to reference our components. We don't want them to duplicate the "wait until configuration is loaded" logic every time, so I tried creating a wrapper component that can be used like so:
<my-app-wrapper>
<my-app-component></my-app-component>
</my-app-wrapper>
The wrapper injects a service object and hides its contents behind an ngIf until the service says that the configuration is loaded.
Like the question poster, I discovered that the ng-content approach doesn't work as intended: while the contents are correctly hidden from the DOM, Angular still instantiates the components causing dependency injection to fail.
The solution that I settled on was to rewrite the wrapper component as a structural directive.
I have an Angular 2 application in which i have a master component containing tree child components.
In one of my child components ( lets call it user_input) i have a form with user input.
in my master component i have a button which needs to check if my form of the child component is valid, thus enabling it.
i have tried to access it via. (from master.view.html)
<user_input #usrInput></user_input><button
[disabled]="!usrInput.formname.form.valid(click)="next()">
Next</button>
But since my user_input form is not initialized at the time i validate om my master this throws an "of type unknown" exception.
Is there a clever way to solve this? i have a service shared by the two but i prefer not to use it for this.
Thanks in advance!
[UPDATE]
I have my child elements in an ngSwitch.
<div *ngSwitchCase="0">
<create-user-info></create-user-info>
</div>
<div *ngSwitchCase="1">
<create-user-services></create-user-services>
</div>
<div class="col-lg-12" *ngSwitchCase="2">
<create-user-conditions></create-user-conditions>
</div>
</div>
once i moved it out of it the error was resolved.
As i needed it to be in an ngSwitch, i used the solution kindly provided below
You could leverage the so-called safe navigation operator. This way, the following members only get evaluated, if usrInput is not null anymore.
<user_input #usrInput></user_input>
<button [disabled]="!usrInput?.formname.form.valid"
(click)="next()">Next</button>
Let me assume that I have the following architecture
_components (folders)
x1.html
x2.html
x3.html
I have a first page where I got the information from the YAM section for every component.
At this point I would like to add a link for every component to another page where I will display the component in a bigger manner.
So, let me assume I have, in the first page :
<div class="col-md-1">
<span id= "logos" class="material-icons"></span>
</div>
and In the componentbig.html I would like to open the right component on the basis of the link.
Do you have any suggestions for me ?
If I understand You correctly, then collections might be the feature You are looking for. For example, I'm usually using collections to generate a list of products and then have a specific page for each product also. Also make sure You check the easy tutorial by Ben Balter.