2150 |
mathias |
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if(!dojo._hasResource["dojox.data.demos.stores.LazyLoadJSIStore"]){ //_hasResource checks added by build. Do not use _hasResource directly in your code.
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dojo._hasResource["dojox.data.demos.stores.LazyLoadJSIStore"] = true;
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dojo.provide("dojox.data.demos.stores.LazyLoadJSIStore");
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dojo.require("dojo.data.ItemFileReadStore");
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dojo.declare("dojox.data.demos.stores.LazyLoadJSIStore", dojo.data.ItemFileReadStore, {
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constructor: function(/* object */ keywordParameters){
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// LazyLoadJSIStore extends ItemFileReadStore to implement an
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// example of lazy-loading/faulting in items on-demand.
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// Note this is certianly not a perfect implementation, it is
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// an example.
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},
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isItemLoaded: function(/*object*/ item) {
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// summary:
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// Overload of the isItemLoaded function to look for items of type 'stub', which indicate
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// the data hasn't been loaded in yet.
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//
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// item:
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// The item to examine.
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//For this store, if it has the value of stub for its type attribute,
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//then the item basn't been fully loaded yet. It's just a placeholder.
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if(this.getValue(item, "type") === "stub"){
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return false;
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}
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return true;
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},
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loadItem: function(keywordArgs){
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// summary:
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// Overload of the loadItem function to fault in items. This assumes the data for an item is laid out
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// in a RESTful sort of pattern name0/name1/data.json and so on and uses that to load the data.
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// It will also detect stub items in the newly loaded item and insert the stubs into the ItemFileReadStore
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// list so they can also be loaded in on-demand.
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//
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// item:
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// The item to examine.
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var item = keywordArgs.item;
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this._assertIsItem(item);
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//Build the path to the data.json for this item
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//The path consists of where its parent was loaded from
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//plus the item name.
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var itemName = this.getValue(item, "name");
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var parent = this.getValue(item, "parent");
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var dataUrl = "";
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if (parent){
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dataUrl += (parent + "/");
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}
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//For this store, all child input data is loaded from a url that ends with data.json
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dataUrl += itemName + "/data.json";
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//Need a reference to the store to call back to its structures.
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var self = this;
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// Callback for handling a successful load.
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var gotData = function(data){
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//Now we need to modify the existing item a bit to take it out of stub state
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//Since we extend the store and have knowledge of the internal
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//structure, this can be done here. Now, is we extended
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//a write store, we could call the write APIs to do this too
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//But for a simple demo the diretc modification in the store function
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//is sufficient.
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//Clear off the stub indicators.
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delete item.type;
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delete item.parent;
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//Set up the loaded values in the format ItemFileReadStore uses for attributes.
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for (i in data) {
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if (dojo.isArray(data[i])) {
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item[i] = data[i];
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}else{
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item[i] = [data[i]];
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}
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}
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//Reset the item in the reference.
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self._arrayOfAllItems[item[self._itemNumPropName]] = item;
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//Scan the new values in the item for extra stub items we need to
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//add to the items array of the store so they can be lazy-loaded later...
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var attributes = self.getAttributes(item);
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for(i in attributes){
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var values = self.getValues(item, attributes[i]);
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for (var j = 0; j < values.length; j++) {
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var value = values[j];
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if(typeof value === "object"){
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if(value["stub"] ){
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//We have a stub reference here, we need to create the stub item
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var stub = {
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type: ["stub"],
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name: [value["stub"]], //
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parent: [itemName] //The child stub item is parented by this item name...
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};
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if (parent) {
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//Add in any parents to your parent so URL construstruction is accurate.
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stub.parent[0] = parent + "/" + stub.parent[0];
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}
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//Finalize the addition of the new stub item into the ItemFileReadStore list.
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self._arrayOfAllItems.push(stub);
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stub[self._storeRefPropName] = self;
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stub[self._itemNumPropName] = (self._arrayOfAllItems.length - 1); //Last one pushed in should be the item
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values[j] = stub; //Set the stub item back in its place and replace the stub notation.
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}
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}
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}
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}
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//Done processing! Call the onItem, if any.
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if(keywordArgs.onItem){
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var scope = keywordArgs.scope ? keywordArgs.scope : dojo.global;
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keywordArgs.onItem.call(scope, item);
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}
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};
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//Callback for any errors that occur during load.
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var gotError = function(error){
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//Call the onComplete, if any
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if(keywordArgs.onError){
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var scope = keywordArgs.scope ? keywordArgs.scope : dojo.global;
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keywordArgs.onError.call(scope, error);
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}
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};
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//Fire the get and pass the proper callbacks to the deferred.
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var xhrArgs = {
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url: dataUrl,
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handleAs: "json-comment-optional"
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};
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var d = dojo.xhrGet(xhrArgs);
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d.addCallback(gotData);
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d.addErrback(gotError);
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}
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});
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}
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