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POstrange behavior of Firebase queries
 

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  1. POstrange behavior of Firebase queries
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    <p>I'm working on an app that stores a list of work items, which are ordered by their scheduled dates. I have 2 queries, 1 to monitor the item having the highest priority (latest schedule), and the other to monitor the one with the lowest priority (earliest schedule):</p> <pre><code> var FB = new Firebase('https://pckben-testquery.firebaseio-demo.com/'); FB.startAt().limit(1).on('child_added', function(snapshot) { var topItems = JSON.stringify(snapshot.name()); $("#topItems").text(topItems); }); FB.endAt().limit(1).on('child_added', function(snapshot) { var lastItems = JSON.stringify(snapshot.name()); $("#lastItems").text(lastItems); }); </code></pre> <p>My data is something like:</p> <pre><code>a: 1365931229230 &lt;-- scheduled date, also set as its priority b: 1365931230662 c: 1365931241984 d: 1365931258729 e: 1365931266804 </code></pre> <p>The result is not as expected: it outputs the top item, "a", for both <code>#topItems</code> and <code>#lastItems</code>. </p> <p>But if I include another query watching the entire list, then everything works as expected:</p> <pre><code> $scope.items = []; // I'm using AngularJS FB.on('value', function(snapshots) { $scope.items = []; snapshots.forEach(function(ss) { $scope.items.push({ name: ss.name(), schedule: ss.val() }); }); if (!$scope.$$phase) $scope.$apply(); }); </code></pre> <p>To understand this behavior, please first go to <a href="http://jsbin.com/azisuf/1/edit" rel="nofollow">http://jsbin.com/azisuf/1/edit</a>, and then <a href="http://jsbin.com/ejujef/1/edit" rel="nofollow">http://jsbin.com/ejujef/1/edit</a>. Clicking the update button to move the items to the last row. You will see that in the first version, the "Last Rows" section doesn't show the last rows as expected, while in the second version it does.</p> <p>The codes are tested on Chrome and Safari.</p>
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    1. USpckben
    1. USpckben
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      1. POstrange behavior of Firebase queries
      1. UShiroshi
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    1. COI was able to reproduce this behavior. If I use `startAt(null)`, then both queries shift to the last value. If I take it out, they both go to the first value. I tried various differences, like `endAt(99999999999999)` or using `new Firebase` for both, with no improvement. http://jsfiddle.net/katowulf/q8dUp/1/
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      1. POstrange behavior of Firebase queries
      1. USKato
    2. COThanks for trying out! It took me my weekend to isolate the problem out of a small app i thought supposed to be quick to build :'(
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      1. POstrange behavior of Firebase queries
      1. USpckben
    3. COHate it when that happens. As a quick fix, why don't you just grab all the data? This will work fine until there are tens of thousands of rows; I'm sure the FB team will have an answer by then.
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      1. POstrange behavior of Firebase queries
      1. USKato
 

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