source: [view]
define("dojo/store/util/SimpleQueryEngine", ["dojo"], function(dojo) {
dojo.getObject("store.util", true, dojo);
dojo.store.util.SimpleQueryEngine = function(query, options){
// summary:
// Simple query engine that matches using filter functions, named filter
// functions or objects by name-value on a query object hash
//
// description:
// The SimpleQueryEngine provides a way of getting a QueryResults through
// the use of a simple object hash as a filter. The hash will be used to
// match properties on data objects with the corresponding value given. In
// other words, only exact matches will be returned.
//
// This function can be used as a template for more complex query engines;
// for example, an engine can be created that accepts an object hash that
// contains filtering functions, or a string that gets evaluated, etc.
//
// When creating a new dojo.store, simply set the store's queryEngine
// field as a reference to this function.
//
// query: Object
// An object hash with fields that may match fields of items in the store.
// Values in the hash will be compared by normal == operator, but regular expressions
// or any object that provides a test() method are also supported and can be
// used to match strings by more complex expressions
// (and then the regex's or object's test() method will be used to match values).
//
// options: dojo.store.util.SimpleQueryEngine.__queryOptions?
// An object that contains optional information such as sort, start, and count.
//
// returns: Function
// A function that caches the passed query under the field "matches". See any
// of the "query" methods on dojo.stores.
//
// example:
// Define a store with a reference to this engine, and set up a query method.
//
// | var myStore = function(options){
// | // ...more properties here
// | this.queryEngine = dojo.store.util.SimpleQueryEngine;
// | // define our query method
// | this.query = function(query, options){
// | return dojo.store.util.QueryResults(this.queryEngine(query, options)(this.data));
// | };
// | };
// create our matching query function
switch(typeof query){
default:
throw new Error("Can not query with a " + typeof query);
case "object": case "undefined":
var queryObject = query;
query = function(object){
for(var key in queryObject){
var required = queryObject[key];
if(required && required.test){
if(!required.test(object[key])){
return false;
}
}else if(required != object[key]){
return false;
}
}
return true;
};
break;
case "string":
// named query
if(!this[query]){
throw new Error("No filter function " + query + " was found in store");
}
query = this[query];
// fall through
case "function":
// fall through
}
function execute(array){
// execute the whole query, first we filter
var results = dojo.filter(array, query);
// next we sort
if(options && options.sort){
results.sort(function(a, b){
for(var sort, i=0; sort = options.sort[i]; i++){
var aValue = a[sort.attribute];
var bValue = b[sort.attribute];
if (aValue != bValue) {
return !!sort.descending == aValue > bValue ? -1 : 1;
}
}
return 0;
});
}
// now we paginate
if(options && (options.start || options.count)){
var total = results.length;
results = results.slice(options.start || 0, (options.start || 0) + (options.count || Infinity));
results.total = total;
}
return results;
}
execute.matches = query;
return execute;