Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>The best use case I can think of is in caching AJAX responses. Here's a modified example from <a href="http://rmurphey.com/blog/2010/12/25/deferreds-coming-to-jquery/" rel="noreferrer">Rebecca Murphey's intro post on the topic</a>:</p> <pre><code>var cache = {}; function getData( val ){ // return either the cached value or jqXHR object wrapped Promise return $.when( cache[ val ] || $.ajax('/foo/', { data: { value: val }, dataType: 'json', success: function( resp ){ cache[ val ] = resp; } }) ); } getData('foo').then(function(resp){ // do something with the response, which may // or may not have been retrieved using an // XHR request. }); </code></pre> <p>Basically, if the value has already been requested once before it's returned immediately from the cache. Otherwise, an AJAX request fetches the data and adds it to the cache. The <code>$.when</code>/<code>.then</code> doesn't care about any of this; all you need to be concerned about is using the response, which is passed to the <code>.then()</code> handler in both cases. <a href="http://api.jquery.com/jQuery.when/" rel="noreferrer"><code>jQuery.when()</code></a> handles a non-Promise/Deferred as a Completed one, immediately executing any <code>.done()</code> or <code>.then()</code> on the chain.</p> <p>Deferreds are perfect for when the task may or may not operate asynchronously, and you want to abstract that condition out of the code.</p> <p>Another real world example using the <code>$.when</code> helper:</p> <pre><code>$.when($.getJSON('/some/data/'), $.get('template.tpl')).then(function (data, tmpl) { $(tmpl) // create a jQuery object out of the template .tmpl(data) // compile it .appendTo("#target"); // insert it into the DOM }); </code></pre>
    singulars
    1. This table or related slice is empty.
    1. POHow can jQuery deferred be used?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USCœur
    1. USehynds
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POHow can jQuery deferred be used?
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COIt's defiantly good to to use $.when().then to abstract away whether the data is asynchronously or synchronolously handled. The buffer does a similar thing except it abstracts away whether a task is handled sychronously or asynchronously.
      singulars
      1. PO
      1. USRaynos
    2. COTwo brilliants examples. I implemented something similar to the 2nd one, but with 4 ajax requests, and it performs well, in addition to be far more legible, compact, logic, maintainable, etc. jQuery.Deferred is a real good thing.
      singulars
      1. PO
      1. USPJP
    3. COHere is a useful video on this topic http://www.bigbinary.com/videos/3-using-deferred-in-jquery
      singulars
      1. PO
      1. USNick Vanderbilt
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload