238 lines
7.6 KiB
JavaScript
238 lines
7.6 KiB
JavaScript
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dojo.provide("dojox.rpc.OfflineRest");
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dojo.require("dojox.data.ClientFilter");
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dojo.require("dojox.rpc.Rest");
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dojo.require("dojox.storage");
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// summary:
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// Makes the REST service be able to store changes in local
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// storage so it can be used offline automatically.
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(function(){
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var Rest = dojox.rpc.Rest;
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var namespace = "dojox_rpc_OfflineRest";
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var loaded;
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var index = Rest._index;
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dojox.storage.manager.addOnLoad(function(){
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// now that we are loaded we need to save everything in the index
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loaded = dojox.storage.manager.available;
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for(var i in index){
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saveObject(index[i], i);
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}
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});
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var dontSave;
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function getStorageKey(key){
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// returns a key that is safe to use in storage
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return key.replace(/[^0-9A-Za-z_]/g,'_');
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}
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function saveObject(object,id){
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// save the object into local storage
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if(loaded && !dontSave && (id || (object && object.__id))){
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dojox.storage.put(
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getStorageKey(id||object.__id),
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typeof object=='object'?dojox.json.ref.toJson(object):object, // makeshift technique to determine if the object is json object or not
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function(){},
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namespace);
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}
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}
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function isNetworkError(error){
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// determine if the error was a network error and should be saved offline
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// or if it was a server error and not a result of offline-ness
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return error instanceof Error && (error.status == 503 || error.status > 12000 || !error.status); // TODO: Make the right error determination
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}
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function sendChanges(){
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// periodical try to save our dirty data
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if(loaded){
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var dirty = dojox.storage.get("dirty",namespace);
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if(dirty){
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for (var dirtyId in dirty){
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commitDirty(dirtyId,dirty);
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}
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}
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}
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}
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var OfflineRest;
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function sync(){
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OfflineRest.sendChanges();
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OfflineRest.downloadChanges();
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}
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var syncId = setInterval(sync,15000);
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dojo.connect(document, "ononline", sync);
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OfflineRest = dojox.rpc.OfflineRest = {
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turnOffAutoSync: function(){
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clearInterval(syncId);
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},
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sync: sync,
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sendChanges: sendChanges,
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downloadChanges: function(){
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},
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addStore: function(/*data-store*/store,/*query?*/baseQuery){
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// summary:
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// Adds a store to the monitored store for local storage
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// store:
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// Store to add
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// baseQuery:
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// This is the base query to should be used to load the items for
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// the store. Generally you want to load all the items that should be
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// available when offline.
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OfflineRest.stores.push(store);
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store.fetch({queryOptions:{cache:true},query:baseQuery,onComplete:function(results,args){
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store._localBaseResults = results;
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store._localBaseFetch = args;
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}});
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}
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};
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OfflineRest.stores = [];
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var defaultGet = Rest._get;
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Rest._get = function(service, id){
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// We specifically do NOT want the paging information to be used by the default handler,
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// this is because online apps want to minimize the data transfer,
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// but an offline app wants the opposite, as much data as possible transferred to
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// the client side
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try{
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// if we are reloading the application with local dirty data in an online environment
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// we want to make sure we save the changes first, so that we get up-to-date
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// information from the server
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sendChanges();
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if(window.navigator && navigator.onLine===false){
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// we force an error if we are offline in firefox, otherwise it will silently load it from the cache
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throw new Error();
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}
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var dfd = defaultGet(service, id);
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}catch(e){
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dfd = new dojo.Deferred();
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dfd.errback(e);
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}
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var sync = dojox.rpc._sync;
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dfd.addCallback(function(result){
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saveObject(result, service.servicePath+id);
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return result;
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});
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dfd.addErrback(function(error){
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if(loaded){
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// if the storage is loaded, we can go ahead and get the object out of storage
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if(isNetworkError(error)){
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var loadedObjects = {};
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// network error, load from local storage
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var byId = function(id,backup){
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if(loadedObjects[id]){
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return backup;
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}
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var result = dojo.fromJson(dojox.storage.get(getStorageKey(id),namespace)) || backup;
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loadedObjects[id] = result;
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for(var i in result){
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var val = result[i]; // resolve references if we can
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if (val && val.$ref){
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result[i] = byId(val.$ref,val);
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}
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}
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if (result instanceof Array){
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//remove any deleted items
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for (i = 0;i<result.length;i++){
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if (result[i]===undefined){
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result.splice(i--,1);
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}
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}
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}
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return result;
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};
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dontSave = true; // we don't want to be resaving objects when loading from local storage
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//TODO: Should this reuse something from dojox.rpc.Rest
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var result = byId(service.servicePath+id);
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if(!result){// if it is not found we have to just return the error
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return error;
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}
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dontSave = false;
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return result;
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}
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else{
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return error; // server error, let the error propagate
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}
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}
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else{
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if(sync){
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return new Error("Storage manager not loaded, can not continue");
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}
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// we are not loaded, so we need to defer until we are loaded
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dfd = new dojo.Deferred();
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dfd.addCallback(arguments.callee);
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dojox.storage.manager.addOnLoad(function(){
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dfd.callback();
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});
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return dfd;
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}
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});
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return dfd;
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};
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//FIXME: Should we make changes after a commit to see if the server rejected the change
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// or should we come up with a revert mechanism?
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var defaultChange = Rest._change;
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Rest._change = function(method,service,id,serializedContent){
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if(!loaded){
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return defaultChange.apply(this,arguments);
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}
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var absoluteId = service.servicePath + id;
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if(method=='delete'){
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dojox.storage.remove(getStorageKey(absoluteId),namespace);
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}
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else{
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// both put and post should store the actual object
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dojox.storage.put(getStorageKey(dojox.rpc.JsonRest._contentId),serializedContent,function(){
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},namespace);
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}
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// record all the updated queries
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var store = service._store;
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if(store){
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store.updateResultSet(store._localBaseResults, store._localBaseFetch);
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dojox.storage.put(getStorageKey(service.servicePath + store._localBaseFetch.query),dojox.json.ref.toJson(store._localBaseResults),function(){
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},namespace);
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}
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var dirty = dojox.storage.get("dirty",namespace) || {};
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if (method=='put' || method=='delete'){
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// these supersede so we can overwrite anything using this id
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var dirtyId = absoluteId;
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}
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else{
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dirtyId = 0;
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for (var i in dirty){
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if(!isNaN(parseInt(i))){
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dirtyId = i;
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}
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} // get the last dirtyId to make a unique id for non-idempotent methods
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dirtyId++;
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}
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dirty[dirtyId] = {method:method,id:absoluteId,content:serializedContent};
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return commitDirty(dirtyId,dirty);
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};
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function commitDirty(dirtyId, dirty){
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var dirtyItem = dirty[dirtyId];
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var serviceAndId = dojox.rpc.JsonRest.getServiceAndId(dirtyItem.id);
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var deferred = defaultChange(dirtyItem.method,serviceAndId.service,serviceAndId.id,dirtyItem.content);
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// add it to our list of dirty objects
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dirty[dirtyId] = dirtyItem;
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dojox.storage.put("dirty",dirty,function(){},namespace);
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deferred.addBoth(function(result){
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if (isNetworkError(result)){
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// if a network error (offlineness) was the problem, we leave it
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// dirty, and return to indicate successfulness
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return null;
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}
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// it was successful or the server rejected it, we remove it from the dirty list
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var dirty = dojox.storage.get("dirty",namespace) || {};
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delete dirty[dirtyId];
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dojox.storage.put("dirty",dirty,function(){},namespace);
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return result;
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});
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return deferred;
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}
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dojo.connect(index,"onLoad",saveObject);
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dojo.connect(index,"onUpdate",saveObject);
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})();
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