model view controller - dojo pattern - when to use set/watch and when to use notify/observe? -

i'm struggling mvc pattern around stateful objects , observable stores. can't find clarity on when use 1 on , mixing them isn't clean i'd hoped. ah! insight how manage observable collection of stateful items?

if item.set("key", value) can item.watch("key", cb) observe-er isn't notify-ed.

i can item.watch(function() { state.notify(item, item.id); }) notify observer if observe-er calls set "query out of date, must observe() query prior data modifications'" error cannot reconcile.

i can decouple via settimeout it's not feeling good.

here's code show i'm trying:

    crudify: function ( store, query, crud )     {         var result;         if ( !crud )         {             crud = query;             query = store;             store = null;         }         if ( store )         {             query = store.query( query );         }         result = query.observe( function ( row, deleteindex, insertindex )         {             var del = ( 0 <= deleteindex ), ins = ( 0 <= insertindex );             !del && ins && crud.c && crud.c( row );             del && ins && crud.u && crud.u( row );             del && !ins && crud.d && crud.d( row );         }, !!crud.u );         crud.c && array.foreach( query, crud.c );         return result;     } 

and have store wrapper (for layers) i'm hacking pieces trying observe-ers notified of data changes without getting errors:

addlayer: function ( item ) {     var = this;     that.store.add(item);     item.watch && item.watch(function (name, prior, curr) {         if (prior !== curr) {             that._queue.push(item);             // attempting eliminate queries indirectly update store (can't find source of error)             infor.delay(20, "layerprocessorstorenotification", function () {                 that._queue.foreach(function (item) {                     that.store.notify(item, that.getlayerid(item));                 });                 that._queue = [];             });         }     });     return item; }, 

the delay method looks this:

    delay: function ( timeout, id, callback )     {         this.delays = this.delays || [];         var delay = this.delays[id];         if ( delay )         {             cleartimeout( delay );         }         delay = settimeout( callback, timeout );         this.delays[id] = delay;     }, 

i can item.watch(function() { state.notify(item, item.id); }) notify observer

i didn't have problems using pattern, but...

but if observe-er calls set "query out of date, must observe() query prior data modifications'" error cannot reconcile.

you shouldn't have watch call notify , have observe call set. choose 1 or other. otherwise you're setting infinite loop of callbacks.

the code below works me. change made crudify function change array.foreach(query, crud.c) query.foreach(crud.c).

<script type="text/javascript" src="../javascripts/dojo-release-1.9.3-src/dojo/dojo.js"></script> <script type="text/javascript">  window.stackoverflow = {     crudify: function ( store, query, crud )     {         var result;         if ( !crud )         {             crud = query;             query = store;             store = null;         }         if ( store )         {             query = store.query( query );         }         result = query.observe( function ( row, deleteindex, insertindex )         {             console.log("observed");             var del = ( 0 <= deleteindex ), ins = ( 0 <= insertindex );             !del && ins && crud.c && crud.c( row );             del && ins && crud.u && crud.u( row );             del && !ins && crud.d && crud.d( row );         }, !!crud.u );         crud.c && query.foreach( crud.c );         return result;     } };  require([     "dojo/store/memory",     "dojo/store/observable",     "dojo/stateful",     "dojo/_base/json",     "dojo/domready!" ], function(memory, observable, stateful, dojo){      var store = observable(new memory({ data: [] }));      var rawdata = [ { id: 1, data: "a" }, { id: 2, data: "b" }, { id: 3, data: "c" }]      var myquery = { id : 3 };      rawdata.foreach(function (obj, index) {       statefulobj = new stateful(obj);       statefulobj.watch(function(name, oldvalue, newvalue) {         console.log("watched");         store.notify(statefulobj, statefulobj.id);       });                                                                   store.put(statefulobj);     });      window.settimeout(function() {          // directly triggers observe() callback         store.notify(store.get(3), 3);     }, 2000);      window.settimeout(function() {          // triggers watch(), indirectly triggers observe() through notify()         store.get(3).set("data", "sea?");     }, 4000);      window.settimeout(function() {                                                              // calls no callbacks because doesn't match query                                                                      store.put({ id: 2, data: "bee" });     }, 6000);      window.settimeout(function() {          // update triggers observe()         store.put(new stateful({ id: 3, data: "see!?!" }));          // note didn't set watch() on new object (see below)     }, 8000);      window.settimeout(function() {          // whoops, doesn't trigger callback because forgot call watch() above         store.get(3).set("data", "c4");     }, 10000);      window.settimeout(function() {          // observe() callback still works         store.notify(store.get(3), 3);     }, 12000);      window.settimeout(function() {          // deletion triggers observe()         store.remove(3);     }, 14000);      stackoverflow.crudify(         store,         myquery,         {           u: function(obj) {             console.log("observed update: obj: " + dojo.tojson(obj));           },           c: function(obj) {             console.log("observed creation: obj: " + dojo.tojson(obj));           },           d: function(obj) {             console.log("observed deletion: obj: " + dojo.tojson(obj));           }         }); }); </script>