Medryx Observations » Uncategorized

June 18, 2008

Pseudo-RESTful

Filed under: Uncategorized — maulin @ 10:40 am

I have to admit it: I spent the last week rolling my own data store that handles lazy loading that I thought was going to be the greatest thing since… well anyway. Then I read this , and realized that there was no need to write almost any of what I had written. I hate when that happens.

In any case, the new JsonRestStore does just about everything I wanted to do, only more efficiently. My only problem is that my server, which I have no control over, has blocked “PUT” and “DELETE”. But really, that seems minor. I mean, couldn’t we just include a flag to our REST server telling it what action we are expecting? Yes. We can.

A detailed look into dojox.rpc.Rest reveals that the _change method is where the final call to xhr occurs. Now I know this is unsafe since this is a private method, but its a good quick fix for now. And perhaps I can convince the dojo folks after 1.2 is official that they should support this kind of behavior for “Pseudo-REST” services, right out of the box.

Here is the code.

/**
 * 
 * uses post for all post/put/delete, but adds and attribute called action
 * 
 * @author maulin
 * 
 */
dojo.provide("medryx.stores.ModifiedRest");
dojo.require("dojox.rpc.Rest");
 
(function() {
 
  //copied verbatim from dojox.rpc.Rest -- it is local in scope inside Rest
 //and called from the _change method, so I need it (for now)
  function index(deferred, service, range, id){
        deferred.addCallback(function(result){
            if(id==""){
                service._rootQueries.push(result);
            }
            if(range){
                // try to record the total number of items from the range header
                range = deferred.ioArgs.xhr.getResponseHeader("Content-Range");
                deferred.fullLength = range && (range=range.match(/\/(.*)/|>)) && parseInt(range[1]);
            }
            return service.cache.intake(result,id);
        });
        return deferred;
    }
 
  //"over-rides" the actual xhr call to use POST and add action attribute to querystring
  dojox.rpc.Rest._change = function(method,service,id,content){
        // this is called to actually do the put, post, and delete
        var request = service._getRequest(id);
        request[method+"Data"] = content;
 
        //ADDED THE FOLLOWING TWO LINES
        request.data += "&action=" + method.toLowerCase();
        request.url += (request.url.indexOf('?') > 0 ? "&" : "?" ) + "action=" + method.toLowerCase();
 
        //CHANGED THIS LINE TO ALWAYS USE POST
        return index(dojo.xhr("POST",request,true),service);
    };
 
})();

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