- 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/data/QueryReadStore.js
dojo.provide("dojox.data.QueryReadStore");
dojo.require("dojo.string");
dojo.require("dojo.data.util.sorter");
dojo.declare("dojox.data.QueryReadStore",
null,
{
// summary:
// This class provides a store that is mainly intended to be used
// for loading data dynamically from the server, used i.e. for
// retreiving chunks of data from huge data stores on the server (by server-side filtering!).
// Upon calling the fetch() method of this store the data are requested from
// the server if they are not yet loaded for paging (or cached).
//
// For example used for a combobox which works on lots of data. It
// can be used to retreive the data partially upon entering the
// letters "ac" it returns only items like "action", "acting", etc.
//
// note:
// The field name "id" in a query is reserved for looking up data
// by id. This is necessary as before the first fetch, the store
// has no way of knowing which field the server will declare as
// identifier.
//
// example:
// | // The parameter "query" contains the data that are sent to the server.
// | var store = new dojox.data.QueryReadStore({url:'/search.php'});
// | store.fetch({query:{name:'a'}, queryOptions:{ignoreCase:false}});
//
// | // Since "serverQuery" is given, it overrules and those data are
// | // sent to the server.
// | var store = new dojox.data.QueryReadStore({url:'/search.php'});
// | store.fetch({serverQuery:{name:'a'}, queryOptions:{ignoreCase:false}});
//
// | <div dojoType="dojox.data.QueryReadStore"
// | jsId="store2"
// | url="../tests/stores/QueryReadStore.php"
// | requestMethod="post"></div>
// | <div dojoType="dojox.grid.data.DojoData"
// | jsId="model2"
// | store="store2"
// | sortFields="[{attribute: 'name', descending: true}]"
// | rowsPerPage="30"></div>
// | <div dojoType="dojox.Grid" id="grid2"
// | model="model2"
// | structure="gridLayout"
// | style="height:300px; width:800px;"></div>
//
// todo:
// - there is a bug in the paging, when i set start:2, count:5 after an initial fetch() and doClientPaging:true
// it returns 6 elemetns, though count=5, try it in QueryReadStore.html
// - add optional caching
// - when the first query searched for "a" and the next for a subset of
// the first, i.e. "ab" then we actually dont need a server request, if
// we have client paging, we just need to filter the items we already have
// that might also be tooo much logic
url:"",
requestMethod:"get",
//useCache:false,
// We use the name in the errors, once the name is fixed hardcode it, may be.
_className:"dojox.data.QueryReadStore",
// This will contain the items we have loaded from the server.
// The contents of this array is optimized to satisfy all read-api requirements
// and for using lesser storage, so the keys and their content need some explaination:
// this._items[0].i - the item itself
// this._items[0].r - a reference to the store, so we can identify the item
// securly. We set this reference right after receiving the item from the
// server.
_items:[],
// Store the last query that triggered xhr request to the server.
// So we can compare if the request changed and if we shall reload
// (this also depends on other factors, such as is caching used, etc).
_lastServerQuery:null,
// Store how many rows we have so that we can pass it to a clientPaging handler
_numRows:-1,
// Store a hash of the last server request. Actually I introduced this
// for testing, so I can check if no unnecessary requests were issued for
// client-side-paging.
lastRequestHash:null,
// summary:
// By default every request for paging is sent to the server.
doClientPaging:false,
// summary:
// By default all the sorting is done serverside before the data is returned
// which is the proper place to be doing it for really large datasets.
doClientSorting:false,
// Items by identify for Identify API
_itemsByIdentity:null,
// Identifier used
_identifier:null,
_features: {'dojo.data.api.Read':true, 'dojo.data.api.Identity':true},
_labelAttr: "label",
constructor: function(/* Object */ params){
dojo.mixin(this,params);
},
getValue: function(/* item */ item, /* attribute-name-string */ attribute, /* value? */ defaultValue){
// According to the Read API comments in getValue() and exception is
// thrown when an item is not an item or the attribute not a string!
this._assertIsItem(item);
if (!dojo.isString(attribute)) {
throw new Error(this._className+".getValue(): Invalid attribute, string expected!");
}
if(!this.hasAttribute(item, attribute)){
// read api says: return defaultValue "only if *item* does not have a value for *attribute*."
// Is this the case here? The attribute doesn't exist, but a defaultValue, sounds reasonable.
if(defaultValue){
return defaultValue;
}
console.log(this._className+".getValue(): Item does not have the attribute '"+attribute+"'.");
}
return item.i[attribute];
},
getValues: function(/* item */ item, /* attribute-name-string */ attribute){
this._assertIsItem(item);
var ret = [];
if(this.hasAttribute(item, attribute)){
ret.push(item.i[attribute]);
}
return ret;
},
getAttributes: function(/* item */ item){
this._assertIsItem(item);
var ret = [];
for(var i in item.i){
ret.push(i);
}
return ret;
},
hasAttribute: function(/* item */ item, /* attribute-name-string */ attribute) {
// summary:
// See dojo.data.api.Read.hasAttribute()
return this.isItem(item) && typeof item.i[attribute]!="undefined";
},
containsValue: function(/* item */ item, /* attribute-name-string */ attribute, /* anything */ value){
var values = this.getValues(item, attribute);
var len = values.length;
for(var i=0; i<len; i++){
if(values[i]==value){
return true;
}
}
return false;
},
isItem: function(/* anything */ something){
// Some basic tests, that are quick and easy to do here.
// >>> var store = new dojox.data.QueryReadStore({});
// >>> store.isItem("");
// false
//
// >>> var store = new dojox.data.QueryReadStore({});
// >>> store.isItem({});
// false
//
// >>> var store = new dojox.data.QueryReadStore({});
// >>> store.isItem(0);
// false
//
// >>> var store = new dojox.data.QueryReadStore({});
// >>> store.isItem({name:"me", label:"me too"});
// false
//
if(something){
return typeof something.r!="undefined" && something.r==this;
}
return false;
},
isItemLoaded: function(/* anything */ something) {
// Currently we dont have any state that tells if an item is loaded or not
// if the item exists its also loaded.
// This might change when we start working with refs inside items ...
return this.isItem(something);
},
loadItem: function(/* object */ args){
if(this.isItemLoaded(args.item)){
return;
}
// Actually we have nothing to do here, or at least I dont know what to do here ...
},
fetch:function(/* Object? */ request){
// summary:
// See dojo.data.util.simpleFetch.fetch() this is just a copy and I adjusted
// only the paging, since it happens on the server if doClientPaging is
// false, thx to http://trac.dojotoolkit.org/ticket/4761 reporting this.
// Would be nice to be able to use simpleFetch() to reduce copied code,
// but i dont know how yet. Ideas please!
request = request || {};
if(!request.store){
request.store = this;
}
var self = this;
var _errorHandler = function(errorData, requestObject){
if(requestObject.onError){
var scope = requestObject.scope || dojo.global;
requestObject.onError.call(scope, errorData, requestObject);
}
};
var _fetchHandler = function(items, requestObject, numRows){
var oldAbortFunction = requestObject.abort || null;
var aborted = false;
var startIndex = requestObject.start?requestObject.start:0;
if (self.doClientPaging==false) {
// For client paging we dont need no slicing of the result.
startIndex = 0;
}
var endIndex = requestObject.count?(startIndex + requestObject.count):items.length;
requestObject.abort = function(){
aborted = true;
if(oldAbortFunction){
oldAbortFunction.call(requestObject);
}
};
var scope = requestObject.scope || dojo.global;
if(!requestObject.store){
requestObject.store = self;
}
if(requestObject.onBegin){
requestObject.onBegin.call(scope, numRows, requestObject);
}
if(requestObject.sort && self.doClientSorting){
items.sort(dojo.data.util.sorter.createSortFunction(requestObject.sort, self));
}
if(requestObject.onItem){
for(var i = startIndex; (i < items.length) && (i < endIndex); ++i){
var item = items[i];
if(!aborted){
requestObject.onItem.call(scope, item, requestObject);
}
}
}
if(requestObject.onComplete && !aborted){
var subset = null;
if (!requestObject.onItem) {
subset = items.slice(startIndex, endIndex);
}
requestObject.onComplete.call(scope, subset, requestObject);
}
};
this._fetchItems(request, _fetchHandler, _errorHandler);
return request; // Object
},
getFeatures: function(){
return this._features;
},
close: function(/*dojo.data.api.Request || keywordArgs || null */ request){
// I have no idea if this is really needed ...
},
getLabel: function(/* item */ item){
// summary:
// See dojo.data.api.Read.getLabel()
if(this._labelAttr && this.isItem(item)){
return this.getValue(item, this._labelAttr); //String
}
return undefined; //undefined
},
getLabelAttributes: function(/* item */ item){
// summary:
// See dojo.data.api.Read.getLabelAttributes()
if(this._labelAttr){
return [this._labelAttr]; //array
}
return null; //null
},
_xhrFetchHandler: function(data, request, fetchHandler, errorHandler){
data = this._filterResponse(data);
if (data.label){
this._labelAttr = data.label;
}
var numRows = data.numRows || -1;
this._items = [];
// Store a ref to "this" in each item, so we can simply check if an item
// really origins form here (idea is from ItemFileReadStore, I just don't know
// how efficient the real storage use, garbage collection effort, etc. is).
dojo.forEach(data.items,function(e){
this._items.push({i:e, r:this});
},this);
var identifier = data.identifier;
this._itemsByIdentity = {};
if(identifier){
this._identifier = identifier;
var i;
for(i = 0; i < this._items.length; ++i){
var item = this._items[i].i;
var identity = item[identifier];
if(!this._itemsByIdentity[identity]){
this._itemsByIdentity[identity] = item;
}else{
throw new Error(this._className+": The json data as specified by: [" + this.url + "] is malformed. Items within the list have identifier: [" + identifier + "]. Value collided: [" + identity + "]");
}
}
}else{
this._identifier = Number;
for(i = 0; i < this._items.length; ++i){
this._items[i].n = i;
}
}
// TODO actually we should do the same as dojo.data.ItemFileReadStore._getItemsFromLoadedData() to sanitize
// (does it really sanititze them) and store the data optimal. should we? for security reasons???
numRows = this._numRows = (numRows === -1) ? this._items.length : numRows;
fetchHandler(this._items, request, numRows);
this._numRows = numRows;
},
_fetchItems: function(request, fetchHandler, errorHandler){
// summary:
// The request contains the data as defined in the Read-API.
// Additionally there is following keyword "serverQuery".
//
// The *serverQuery* parameter, optional.
// This parameter contains the data that will be sent to the server.
// If this parameter is not given the parameter "query"'s
// data are sent to the server. This is done for some reasons:
// - to specify explicitly which data are sent to the server, they
// might also be a mix of what is contained in "query", "queryOptions"
// and the paging parameters "start" and "count" or may be even
// completely different things.
// - don't modify the request.query data, so the interface using this
// store can rely on unmodified data, as the combobox dijit currently
// does it, it compares if the query has changed
// - request.query is required by the Read-API
//
// I.e. the following examples might be sent via GET:
// fetch({query:{name:"abc"}, queryOptions:{ignoreCase:true}})
// the URL will become: /url.php?name=abc
//
// fetch({serverQuery:{q:"abc", c:true}, query:{name:"abc"}, queryOptions:{ignoreCase:true}})
// the URL will become: /url.php?q=abc&c=true
// // The serverQuery-parameter has overruled the query-parameter
// // but the query parameter stays untouched, but is not sent to the server!
// // The serverQuery contains more data than the query, so they might differ!
//
var serverQuery = request.serverQuery || request.query || {};
//Need to add start and count
if(!this.doClientPaging){
serverQuery.start = request.start || 0;
// Count might not be sent if not given.
if (request.count) {
serverQuery.count = request.count;
}
}
if(!this.doClientSorting){
if(request.sort){
var sort = request.sort[0];
if(sort && sort.attribute){
var sortStr = sort.attribute;
if(sort.descending){
sortStr = "-" + sortStr;
}
serverQuery.sort = sortStr;
}
}
}
// Compare the last query and the current query by simply json-encoding them,
// so we dont have to do any deep object compare ... is there some dojo.areObjectsEqual()???
if(this.doClientPaging && this._lastServerQuery!==null &&
dojo.toJson(serverQuery)==dojo.toJson(this._lastServerQuery)
){
this._numRows = (this._numRows === -1) ? this._items.length : this._numRows;
fetchHandler(this._items, request, this._numRows);
}else{
var xhrFunc = this.requestMethod.toLowerCase()=="post" ? dojo.xhrPost : dojo.xhrGet;
var xhrHandler = xhrFunc({url:this.url, handleAs:"json-comment-optional", content:serverQuery});
xhrHandler.addCallback(dojo.hitch(this, function(data){
this._xhrFetchHandler(data, request, fetchHandler, errorHandler);
}));
xhrHandler.addErrback(function(error){
errorHandler(error, request);
});
// Generate the hash using the time in milliseconds and a randon number.
// Since Math.randon() returns something like: 0.23453463, we just remove the "0."
// probably just for esthetic reasons :-).
this.lastRequestHash = new Date().getTime()+"-"+String(Math.random()).substring(2);
this._lastServerQuery = dojo.mixin({}, serverQuery);
}
},
_filterResponse: function(data){
// summary:
// If the data from servers needs to be processed before it can be processed by this
// store, then this function should be re-implemented in subclass. This default
// implementation just return the data unchanged.
// data:
// The data received from server
return data;
},
_assertIsItem: function(/* item */ item){
// summary:
// It throws an error if item is not valid, so you can call it in every method that needs to
// throw an error when item is invalid.
// item:
// The item to test for being contained by the store.
if(!this.isItem(item)){
throw new Error(this._className+": Invalid item argument.");
}
},
_assertIsAttribute: function(/* attribute-name-string */ attribute){
// summary:
// This function tests whether the item passed in is indeed a valid 'attribute' like type for the store.
// attribute:
// The attribute to test for being contained by the store.
if(typeof attribute !== "string"){
throw new Error(this._className+": Invalid attribute argument ('"+attribute+"').");
}
},
fetchItemByIdentity: function(/* Object */ keywordArgs){
// summary:
// See dojo.data.api.Identity.fetchItemByIdentity()
// See if we have already loaded the item with that id
// In case there hasn't been a fetch yet, _itemsByIdentity is null
// and thus a fetch will be triggered below.
if(this._itemsByIdentity){
var item = this._itemsByIdentity[keywordArgs.identity];
if(!(item === undefined)){
if(keywordArgs.onItem){
var scope = keywordArgs.scope?keywordArgs.scope:dojo.global;
keywordArgs.onItem.call(scope, {i:item, r:this});
}
return;
}
}
// Otherwise we need to go remote
// Set up error handler
var _errorHandler = function(errorData, requestObject){
var scope = keywordArgs.scope?keywordArgs.scope:dojo.global;
if(keywordArgs.onError){
keywordArgs.onError.call(scope, errorData);
}
};
// Set up fetch handler
var _fetchHandler = function(items, requestObject){
var scope = keywordArgs.scope?keywordArgs.scope:dojo.global;
try{
// There is supposed to be only one result
var item = null;
if(items && items.length == 1){
item = items[0];
}
// If no item was found, item is still null and we'll
// fire the onItem event with the null here
if(keywordArgs.onItem){
keywordArgs.onItem.call(scope, item);
}
}catch(error){
if(keywordArgs.onError){
keywordArgs.onError.call(scope, error);
}
}
};
// Construct query
var request = {serverQuery:{id:keywordArgs.identity}};
// Dispatch query
this._fetchItems(request, _fetchHandler, _errorHandler);
},
getIdentity: function(/* item */ item){
// summary:
// See dojo.data.api.Identity.getIdentity()
var identifier = null;
if(this._identifier === Number){
identifier = item.n; // Number
}else{
identifier = item.i[this._identifier];
}
return identifier;
},
getIdentityAttributes: function(/* item */ item){
// summary:
// See dojo.data.api.Identity.getIdentityAttributes()
return [this._identifier];
}
}
);
