title: How to handle a single failure during saving a batch of records with ExtJS 4.1?
body: <p>Suppose I have an <code>Ext.grid.Panel</code> containing a list of users. After some update operations I send the batch of modified records to a remote database :</p>
  
  <pre><code>[{"id":1,"login":"Jack"},{"id":2,"login":"Jack"}] // request body
  </code></pre>
  
  <p>At the server side, I store one record after the other in the database. Knowing that login name must be unique, the second record is not stored because "Jack" is no longer available. Then, I have to notify the user that he made a mistake marking the related grid cell dirty. Is there a way to let ExtJS handle that? A flag in the JSON response for example?</p>
  
  <hr>
  
  <h2>Update</h2>
  
  <p>Sometimes I need even more precision, marking invalid only one field of a single record. As an example, suppose I want to update two fields of a single record, "login" and "favorite" :</p>
  
  <pre><code>[{"id":1,"login":"Jack","favorite":true}] // request body
  </code></pre>
  
  <p>Both fields are sent together to the same URL then processed separatly via two different SQL queries, but saving "login" succeed while saving "favorite" fails. Is ExtJS able to treat each field separatly from a single JSON response?</p>
  
  <hr>
  
  <h2>Update</h2>
  
  <p>Ultimately, the main question is : what are the best practices about connecting the ExtJS 4 data package with a server side CRUD API ? </p>
  
  <p>Could you share your own experience on these related topics : server side CRUD architecture, request body versus HTTP POST parameters, batch of records versus single record, error handling and JSON response... ?</p>
  
  <p>Here is my own working environment :</p>
  
  <ul>
  <li>ASP.NET 3.5</li>
  <li>ExtJS 4.1.1a</li>
  <li>Ext.data.proxy.Ajax</li>
  </ul>