- Author:
- David Nickerson <nickerso@users.sourceforge.net>
- Date:
- 2009-07-16 02:00:03+12:00
- Desc:
- the starting point for the HH tutorial example
- Permanent Source URI:
- https://models.fieldml.org/workspace/a1/rawfile/f6a8f90307388eb4b040ee3566b84d88b59247f7/dojo-presentation/js/dojo/dojox/rpc/LocalStorageRest.js
dojo.provide("dojox.rpc.LocalStorageRest");
dojo.require("dojox.data.ClientFilter");
dojo.require("dojox.rpc.Rest");
dojo.require("dojox.storage");
// summary:
// Makes the REST service be able to store changes in local
// storage so it can be used offline automatically.
(function(){
var Rest = dojox.rpc.Rest;
var namespace = "dojox_rpc_LocalStorageRest";
var loaded;
var index = Rest._index;
dojox.storage.manager.addOnLoad(function(){
// now that we are loaded we need to save everything in the index
loaded = dojox.storage.manager.available;
for(var i in index){
saveObject(index[i], i);
}
});
var dontSave;
function getStorageKey(key){
// returns a key that is safe to use in storage
return key.replace(/[^0-9A-Za-z_]/g,'_');
}
function saveObject(object,id){
// save the object into local storage
if(loaded && !dontSave && (id || (object && object.__id))){
dojox.storage.put(
getStorageKey(id||object.__id),
typeof object=='object'?dojox.json.ref.toJson(object):object, // makeshift technique to determine if the object is json object or not
function(){},
namespace);
}
}
function isNetworkError(error){
// determine if the error was a network error and should be saved offline
// or if it was a server error and not a result of offline-ness
return error instanceof Error && (error.status == 503 || error.status > 12000 || !error.status); // TODO: Make the right error determination
}
function sendChanges(){
// periodical try to save our dirty data
if(loaded){
var dirty = dojox.storage.get("dirty",namespace);
if(dirty){
for (var dirtyId in dirty){
commitDirty(dirtyId,dirty);
}
}
}
}
var lsr;
function sync(){
lsr.sendChanges();
lsr.downloadChanges();
}
var syncId = setInterval(sync,15000);
lsr = dojox.rpc.LocalStorageRest = {
turnOffAutoSync: function(){
clearInterval(syncId);
},
sync: sync,
sendChanges: sendChanges,
downloadChanges: function(){
},
addStore: function(/*data-store*/store,/*query?*/baseQuery){
// summary:
// Adds a store to the monitored store for local storage
// store:
// Store to add
// baseQuery:
// This is the base query to should be used to load the items for
// the store. Generally you want to load all the items that should be
// available when offline.
lsr.stores.push(store);
store.fetch({queryOptions:{cache:true},query:baseQuery,onComplete:function(results,args){
store._localBaseResults = results;
store._localBaseFetch = args;
}});
}
};
lsr.stores = [];
var defaultGet = Rest._get;
Rest._get = function(service, id){
// We specifically do NOT want the paging information to be used by the default handler,
// this is because online apps want to minimize the data transfer,
// but an offline app wants the opposite, as much data as possible transferred to
// the client side
try{
var dfd = defaultGet(service, id);
}catch(e){
dfd = new dojo.Deferred();
dfd.errback(e);
}
var sync = dojox.rpc._sync;
dfd.addCallback(function(result){
saveObject(result, service.servicePath+id);
return result;
});
dfd.addErrback(function(error){
if(loaded){
// if the storage is loaded, we can go ahead and get the object out of storage
if(isNetworkError(error)){
var loadedObjects = {};
// network error, load from local storage
var byId = function(id,backup){
if(loadedObjects[id]){
return backup;
}
var result = dojo.fromJson(dojox.storage.get(getStorageKey(id),namespace)) || backup;
loadedObjects[id] = result;
for(var i in result){
var val = result[i]; // resolve references if we can
if (val && val.$ref){
result[i] = byId(val.$ref,val);
}
}
if (result instanceof Array){
//remove any deleted items
for (i = 0;i<result.length;i++){
if (result[i]===undefined){
result.splice(i--,1);
}
}
}
return result;
};
dontSave = true; // we don't want to be resaving objects when loading from local storage
//TODO: Should this reuse something from dojox.rpc.Rest
var result = byId(service.servicePath+id);
if(!result){// if it is not found we have to just return the error
return error;
}
dontSave = false;
return result;
}
else{
return error; // server error, let the error propagate
}
}
else{
if(sync){
return new Error("Storage manager not loaded, can not continue");
}
// we are not loaded, so we need to defer until we are loaded
dfd = new dojo.Deferred();
dfd.addCallback(arguments.callee);
dojo.connect(dojox.storage.manager,"loaded", function(){
dfd.callback();
});
return dfd;
}
});
return dfd;
};
//FIXME: Should we make changes after a commit to see if the server rejected the change
// or should we come up with a revert mechanism?
var defaultChange = Rest._change;
Rest._change = function(method,service,id,serializedContent){
if(!loaded){
return defaultChange.apply(this,arguments);
}
var absoluteId = service.servicePath + id;
if(method=='delete'){
dojox.storage.remove(getStorageKey(absoluteId),namespace);
}
else{
// both put and post should store the actual object
dojox.storage.put(getStorageKey(dojox.rpc.JsonRest._contentId),serializedContent,function(){
},namespace);
}
// record all the updated queries
var store = service._store;
if(store){
store.updateResultSet(store._localBaseResults, store._localBaseFetch);
dojox.storage.put(getStorageKey(service.servicePath + store._localBaseFetch.query),dojox.json.ref.toJson(store._localBaseResults),function(){
},namespace);
}
var dirty = dojox.storage.get("dirty",namespace) || {};
if (method=='put' || method=='delete'){
// these supersede so we can overwrite anything using this id
var dirtyId = absoluteId;
}
else{
dirtyId = 0;
for (var i in dirty){
if(!isNaN(parseInt(i))){
dirtyId = i;
}
} // get the last dirtyId to make a unique id for non-idempotent methods
dirtyId++;
}
dirty[dirtyId] = {method:method,id:absoluteId,content:serializedContent};
return commitDirty(dirtyId,dirty);
};
function commitDirty(dirtyId, dirty){
var dirtyItem = dirty[dirtyId];
var serviceAndId = dojox.rpc.JsonRest.getServiceAndId(dirtyItem.id);
var deferred = defaultChange(dirtyItem.method,serviceAndId.service,serviceAndId.id,dirtyItem.content);
// add it to our list of dirty objects
dirty[dirtyId] = dirtyItem;
dojox.storage.put("dirty",dirty,function(){},namespace);
deferred.addBoth(function(result){
if (isNetworkError(result)){
// if a network error (offlineness) was the problem, we leave it
// dirty, and return to indicate successfulness
return null;
}
// it was successful or the server rejected it, we remove it from the dirty list
var dirty = dojox.storage.get("dirty",namespace) || {};
delete dirty[dirtyId];
dojox.storage.put("dirty",dirty,function(){},namespace);
return result;
});
return deferred;
}
dojo.connect(index,"onLoad",saveObject);
dojo.connect(index,"onUpdate",saveObject);
})();
