In this pattern, I'd prefer callbacks to promises, something like:
this.fire('share-item',{id, target, message, callback(err, result});
Promises are still not mainstream, and callbacks are well understood.
Aleks
On Monday, October 5, 2015 at 1:28:56 PM UTC-7, Phred Lane wrote:
>
> I'm making an application that functions as a front end for a service. It
> doesn't do any work itself. It just let's the outter page know that it
> wants things to be done through events.
>
> For instance, it fires events like:
>
> this.fire('delete-item', {id});
>
> this.fire('edit-item', {id, title});
>
> this.fire('share-item',{id, target, message});
>
> If the request can fail or I care about the response, I have a wrapper
> around `this.fire` that fires with a deferred object and the data. This is
> so I can show the end user feedback "Deleted X items successfully" or
> "Failed to update the title for Y".
>
> this.firePromise('delete-item', {id});
>
>
> this.firePromise('edit-item', {id, title});
>
>
> this.firePromise('share-item',{id, target, message});
>
> For reference, this is the definition of the Promisable mixin:
>
> Polymer.Promisable = {
> defer: function() {
> return Q.defer();
> },
> firePromise: function(name, data) {
> var deferred = this.defer();
>
> deferred.data = data;
>
>
> this.fire(name, deferred);
>
>
> return deferred;
> }
> };
>
>
> The otuter page catches the events, does the needful, and resolves/rejects
> the promise as needed. Here's an example:
>
> widget.addEventListener('delete-item', function(e) {
> var deferred = e.detail;
> var data = deferred.data;
>
> fetch(`/rest/endpoint/items/${data.id}`, deleteOptions)
> .then(function(result) {
> deferred.resolve();
> widget.items = result.items;
> })
> .catch(deferred.reject)
> ;
>
> });
>
> I'm not responsible for making the requests to the backend myself, because
> the goal is for me not to care. I'm just expressing how I want the data to
> be managed.
>
> Is this a weird pattern? Is there an alternative (better and/or more
> Polymer-esque) way to get the same functionality? I don't want to use fetch
> wrapped in an element, because I don't care if they use fetch, $.ajax, or
> any other method to get the data. I want them to be free to handle my
> events as they see fit.
>
> I'm generally just looking for feedback on this pattern.
>
>
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