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POPossible Meteor bug in manual publish/subscribe scenario
 

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  1. POPossible Meteor bug in manual publish/subscribe scenario
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    <p>I am encountering a problem with subscribing/publishing in Meteor. I've written an example Meteor app to help narrow the scope of the problem.</p> <p>I am publishing a collection on the server that is filtered by a parameter passed in through a subscription on the client. This subscription is within an autosubscribe, which leverages a session variable to reactively update the subscriptions.</p> <p>When changing the state of this particular session variable, the collection on the client isn't getting updated properly, or at least that's what I gather. I've spent the whole day on this and have not found an issue in code I control. I suspect I'm either not understanding how to setup proper pub-sub in Meteor, or there's a problem within Meteor.</p> <p>To reproduce the problem, start a new Meteor project and use the following (Make sure to remove the autopublish package when trying it out):</p> <p><strong>HTML (test.html for example):</strong></p> <pre><code>&lt;head&gt; &lt;title&gt;pubsubbug&lt;/title&gt; &lt;/head&gt; &lt;body&gt; {{&gt; main}} &lt;/body&gt; &lt;template name="main"&gt; &lt;h1&gt;Example showing possible bug in Meteor wrt pub-sub&lt;/h1&gt; &lt;p&gt;&lt;button name="showall"&gt;show all ({{showall}})&lt;/button&gt;&lt;/p&gt; &lt;div style="float:left;width:400px;"&gt; &lt;h2&gt;Notes:&lt;/h2&gt; &lt;ul&gt; {{#each notes}} &lt;li&gt;{{title}}&lt;/li&gt; {{/each}} &lt;/ul&gt; &lt;/div&gt; &lt;div style="float:left;"&gt; &lt;h2&gt;Notes (copied):&lt;/h2&gt; &lt;ul&gt; {{#each notes_copied}} &lt;li&gt;{{title}}&lt;/li&gt; {{/each}} &lt;/ul&gt; &lt;/div&gt; &lt;/template&gt; </code></pre> <p><strong>JS (test.js for example)</strong></p> <pre><code>if (Meteor.is_client) { Notes = new Meteor.Collection("notes_collection"); NotesCopied = new Meteor.Collection("notes_collection_copied"); Session.set("showall", false); Meteor.autosubscribe(function () { Meteor.subscribe("notes_subscription", Session.get("showall"), function () { console.log("Notes count:", Notes.find().count()); }); Meteor.subscribe("notes_subscription_copied", Session.get("showall"), function () { console.log("Bug? This isn't getting called."); console.log("NotesCopied count:", NotesCopied.find().count()); }); }); Template.main.notes = function () { return Notes.find(); }; Template.main.notes_copied = function () { return NotesCopied.find(); }; Template.main.showall = function () { return Session.get("showall"); }; Template.main.events = { "click button[name='showall']": function (evt) { Session.set("showall", !Session.get("showall")); } }; } if (Meteor.is_server) { Notes = new Meteor.Collection("notes_collection"); var getNotes = function (showall) { if (showall) { return Notes.find({}, {sort: {title: 1}}); } else { return Notes.find({visible: true}, {sort: {title: 1}}); } }; Meteor.publish("notes_subscription", function (showall) { // By sending the Notes back with the same uuid as before, the // client end seems to get confused: return getNotes(showall); }); Meteor.publish("notes_subscription_copied", function (showall) { var notes = getNotes(showall); var self = this; // Copy notes into a new notes collection (see NotesCopied on client). // By generating a new uuid, we don't get an issue with the notes // on the client getting screwed up: notes.forEach(function (note) { var uuid = Meteor.uuid(); // note._id will cause same problem self.set("notes_collection_copied", uuid, {title: note.title}); }); self.flush(); self.complete(); }); // Add example notes Meteor.startup(function () { if (Notes.find().count() === 0) { Notes.insert({title: "Note #1 (always visible)", visible: true}); Notes.insert({title: "Note #2 (always visible)", visible: true}); Notes.insert({title: "Note #3 (always visible)", visible: true}); Notes.insert({title: "Note #4 (only visible when showall true)", visible: false}); Notes.insert({title: "Note #5 (only visible when showall true)", visible: false}); Notes.insert({title: "Note #6 (only visible when showall true)", visible: false}); } }); } </code></pre> <p><em>An explanation of what you will be seeing:</em></p> <p>There will be a button that, when clicked, simply toggles a session variable (showall) between true and false.</p> <p>Two subscriptions exist (within an autosubscribe), one that exemplifies the bug, and another that is suffixed with <code>_copied</code>, which is a test to demonstrate that when the collection in question is "copied" and new uuid's are assigned, the results are displayed properly. I couldn't figure out what to do with this particular bit of info... I don't want new uuid's.</p> <p>So basically, when the <em>show all</em> button is clicked repeatedly, the first column <em>Notes:</em> will display incorrect results, and after a few clicks won't show anything.</p> <p>On the other hand, the second column <em>Notes (copied):</em>, whose uuid's are re-generated each time, shows up correctly.</p> <p>Is this a bug? Or is there a proper way to do this?</p> <p>EDIT: Example above live over at <a href="http://pubsubbug.meteor.com/" rel="nofollow">http://pubsubbug.meteor.com/</a></p>
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