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POMessage stream using JQuery PeriodicUpdater and Rails
 

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  1. POMessage stream using JQuery PeriodicUpdater and Rails
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    <p>I'm trying to create an AJAX message stream in my Rails 3 app using jQuery. The app shows posts and replies to the post. Right now it requires the user to refresh the browser to update:</p> <pre><code>//in app/views/posts/_replies.html.erb &lt;div class="replies"&gt; &lt;% for reply in @replies %&gt; &lt;div class="reply"&gt; &lt;p&gt;&lt;%= reply.body %&gt;&lt;/p&gt; &lt;/div&gt; &lt;% end %&gt; &lt;/div&gt; </code></pre> <p>I'm trying to use the jQuery port of PeriodicalUpdater (https://github.com/RobertFischer/JQuery-PeriodicalUpdater/) to ajaxify the replies as a constantly-updating stream.</p> <p>Based on Ryan Bates' Railscast (http://railscasts.com/episodes/136-jquery), here is what I've got:</p> <pre><code>// in public/javascripts/application.js $(document).ready(function(){ $.PeriodicalUpdater('/replies', { method: 'post', data: ???, minTimeout: 1000, maxTimeout: 8000, multiplier: 2, type: 'json', maxCalls: 0, autoStop: 0 }, function(data) { ???? }); }); </code></pre> <p>I'm new to js and jQuery, so it's not really clear to me how to pass the current post to the server nor how to have it automatically render the <code>replies</code> partial. Here is the rest of my code:</p> <pre><code>// in app/views/posts/show.js.erb $("#replies").append("&lt;%= escape_javascript(render 'replies') %&gt;"); // app/controllers/posts_controller.rb class PostsController &lt; ApplicationController def replies @replies = Post.find(params[:id]).replies respond_to do |format| format.js end end end </code></pre> <p>Is there some way to pass the ID of the current <code>post</code> to the controller? Maybe even pass the ID of the last <code>reply</code> so the server will only send back new replies?</p> <p>Also, do I have to manually append everything inside of the callback function of PeriodicalUpdater? Or is there a way to render the <code>show</code> partial for the updates?</p> <p><strong>Update</strong>: I did like @Spencer suggested below, changing it to first have a button that you push to do an AJAX update.</p> <p>I'm having trouble passing that parameter. My actual code looks up things based on a unique URL key, so I just have:</p> <pre><code>&lt;input type="button" value="Refresh" onclick="getReplies('&lt;%= @post.url_key %&gt;');" /&gt; </code></pre> <p>Then in my application.js file:</p> <pre><code>function getReplies(url_key) { $.ajax({ type: "POST", contentType: "application/json; charset=utf-8", dataType: "json", url: "/replies", data: { url_key: url_key }, success: function(msg) { $.each(msg.Replies, function(index, reply) { $("#replies").prepend('&lt;p&gt;' + reply.body + '&lt;/p&gt;') }); } }); } </code></pre> <p>In my controller, I have:</p> <pre><code>def replies @post = Post.find_by_url_key(params[:url_key]) respond_to do |format| format.json { render :json =&gt; @post.replies } end end </code></pre> <p>I get:</p> <pre><code>Processing by PostsController#replies as JSON Parameters: {"_json"=&gt;"url_key=some-post"} ←[1m←[35mPost Load (1.0ms)←[0m SELECT `posts`.* FROM `posts` WHERE (`posts`.`url_key` IS NULL) LIMIT 1 </code></pre> <p>So it looks like the parameter isn't being retrieved from <code>params</code>.</p>
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