store.js

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    // private
    // Called as a callback by the Reader during a load operation.
    loadRecords : function(o, options, success){
        if(!o || success === false){
            if(success !== false){
                this.fireEvent("load", this, [], options);
            }
            if(options.callback){
                options.callback.call(options.scope || this, [], options, false);
            }
            return;
        }
        var r = o.records, t = o.totalRecords || r.length;
        if(!options || options.add !== true){
            for(var i = 0, len = r.length; i < len; i++){
                r[i].join(this);
            }
            this.data.clear();
            this.data.addAll(r);
            this.totalLength = t;
            this.applySort();
            this.fireEvent("datachanged", this);
        }else{
            this.totalLength = Math.max(t, this.data.length+r.length);
            this.add(r);
        }
        this.fireEvent("load", this, r, options);
        if(options.callback){
            options.callback.call(options.scope || this, r, options, true);
        }
    },

    /**
     * Loads data from a passed data block. A Reader which understands the format of the data
     * must have been configured in the constructor.
     * @param {Object} data The data block from which to read the Records.  The format of the data expected
     * is dependent on the type of Reader that is configured and should correspond to that Reader's readRecords parameter.
     * @param {Boolean} append (Optional) True to append the new Records rather than replace the existing cache.
     */
    loadData : function(o, append){
        var r = this.reader.readRecords(o);
        this.loadRecords(r, {add: append}, true);
    },

    /**
     * Gets the number of cached records.
     * <p>
     * <em>If using paging, this may not be the total size of the dataset. If the data object
     * used by the Reader contains the dataset size, then the getTotalCount() function returns
     * the data set size</em>
     */
    getCount : function(){
        return this.data.length || 0;
    },

    /**
     * Gets the total number of records in the dataset.
     * <p>
     * <em>If using paging, for this to be accurate, the data object used by the Reader must contain
     * the dataset size</em>
     */
    getTotalCount : function(){
        return this.totalLength || 0;
    },

    /**
     * Returns the sort state of the Store as an object with two properties:
     * <pre><code>
 field {String} The name of the field by which the Records are sorted
 direction {String} The sort order, "ASC" or "DESC"
     * </code></pre>
     */
    getSortState : function(){
        return this.sortInfo;
    },

    // private
    applySort : function(){
        if(this.sortInfo && !this.remoteSort){
            var s = this.sortInfo, f = s.field;
            var st = this.fields.get(f).sortType;
            var fn = function(r1, r2){
                var v1 = st(r1.data[f]), v2 = st(r2.data[f]);
                return v1 > v2 ? 1 : (v1 < v2 ? -1 : 0);
            };
            this.data.sort(s.direction, fn);
            if(this.snapshot && this.snapshot != this.data){
                this.snapshot.sort(s.direction, fn);
            }
        }
    },

    /**
     * Sets the default sort column and order to be used by the next load operation.
     * @param {String} fieldName The name of the field to sort by.
     * @param {String} dir (optional) The sort order, "ASC" or "DESC" (defaults to "ASC")
     */
    setDefaultSort : function(field, dir){
        this.sortInfo = {field: field, direction: dir ? dir.toUpperCase() : "ASC"};
    },

    /**
     * Sort the Records.
     * If remote sorting is used, the sort is performed on the server, and the cache is
     * reloaded. If local sorting is used, the cache is sorted internally.
     * @param {String} fieldName The name of the field to sort by.
     * @param {String} dir (optional) The sort order, "ASC" or "DESC" (defaults to "ASC")
     */
    sort : function(fieldName, dir){
        var f = this.fields.get(fieldName);
        if(!dir){
            if(this.sortInfo && this.sortInfo.field == f.name){ // toggle sort dir
                dir = (this.sortToggle[f.name] || "ASC").toggle("ASC", "DESC");
            }else{
                dir = f.sortDir;
            }
        }
        this.sortToggle[f.name] = dir;
        this.sortInfo = {field: f.name, direction: dir};
        if(!this.remoteSort){
            this.applySort();
            this.fireEvent("datachanged", this);
        }else{
            this.load(this.lastOptions);
        }
    },

    /**
     * Calls the specified function for each of the Records in the cache.
     * @param {Function} fn The function to call. The Record is passed as the first parameter.
     * Returning <em>false</em> aborts and exits the iteration.
     * @param {Object} scope (optional) The scope in which to call the function (defaults to the Record).
     */
    each : function(fn, scope){
        this.data.each(fn, scope);
    },

    /**
     * Get all records modified since the last load, or since the last commit.
     * @return {Ext.data.Record[]} An array of Records containing outstanding modifications.
     */
    getModifiedRecords : function(){
        return this.modified;
    },

    // private
    createFilterFn : function(property, value, anyMatch){
        if(!value.exec){ // not a regex
            value = String(value);
            if(value.length == 0){
                return false;
            }
            value = new RegExp((anyMatch === true ? '' : '^') + Ext.escapeRe(value), "i");
        }
        return function(r){
            return value.test(r.data[property]);
        };
    },

    /**
     * Sums the value of <i>property</i> for each record between start and end and returns the result.
     * @param {String} property A field on your records
     * @param {Number} start The record index to start at (defaults to 0)
     * @param {Number} end The last record index to include (defaults to length - 1)
     * @return {Number} The sum
     */
    sum : function(property, start, end){
        var rs = this.data.items, v = 0;
        start = start || 0;
        end = (end || end === 0) ? end : rs.length-1;

        for(var i = start; i <= end; i++){
            v += (rs[i].data[property] || 0);
        }
        return v;
    },

    /**
     * Filter the records by a specified property.
     * @param {String} field A field on your records
     * @param {String/RegExp} value Either a string that the field
     * should start with or a RegExp to test against the field
     * @param {Boolean} anyMatch True to match any part not just the beginning
     */
    filter : function(property, value, anyMatch){
        var fn = this.createFilterFn(property, value, anyMatch);
        return fn ? this.filterBy(fn) : this.clearFilter();
    },

    /**
     * Filter by a function. The specified function will be called with each
     * record in this data source. If the function returns true the record is included,
     * otherwise it is filtered.
     * @param {Function} fn The function to be called, it will receive 2 args (record, id)
     * @param {Object} scope (optional) The scope of the function (defaults to this)
     */
    filterBy : function(fn, scope){
        this.snapshot = this.snapshot || this.data;
        this.data = this.queryBy(fn, scope||this);
        this.fireEvent("datachanged", this);
    },

    /**
     * Query the records by a specified property.
     * @param {String} field A field on your records
     * @param {String/RegExp} value Either a string that the field
     * should start with or a RegExp to test against the field
     * @param {Boolean} anyMatch True to match any part not just the beginning
     * @return {MixedCollection} Returns an Ext.util.MixedCollection of the matched records
     */
    query : function(property, value, anyMatch){
        var fn = this.createFilterFn(property, value, anyMatch);
        return fn ? this.queryBy(fn) : this.data.clone();
    },

    /**
     * Query by a function. The specified function will be called with each
     * record in this data source. If the function returns true the record is included
     * in the results.
     * @param {Function} fn The function to be called, it will receive 2 args (record, id)
     * @param {Object} scope (optional) The scope of the function (defaults to this)
      @return {MixedCollection} Returns an Ext.util.MixedCollection of the matched records
     **/
    queryBy : function(fn, scope){
        var data = this.snapshot || this.data;
        return data.filterBy(fn, scope||this);
    },

    /**
     * Collects unique values for a particular dataIndex from this store.
     * @param {String} dataIndex The property to collect
     * @param {Boolean} allowNull (optional) Pass true to allow null, undefined or empty string values
     * @param {Boolean} bypassFilter (optional) Pass true to collect from all records, even ones which are filtered
     * @return {Array} An array of the unique values
     **/
    collect : function(dataIndex, allowNull, bypassFilter){
        var d = (bypassFilter === true && this.snapshot) ?
                this.snapshot.items : this.data.items;
        var v, sv, r = [], l = {};
        for(var i = 0, len = d.length; i < len; i++){
            v = d[i].data[dataIndex];
            sv = String(v);
            if((allowNull || !Ext.isEmpty(v)) && !l[sv]){
                l[sv] = true;
                r[r.length] = v;
            }
        }
        return r;
    },

    /**
     * Revert to a view of the Record cache with no filtering applied.
     * @param {Boolean} suppressEvent If true the filter is cleared silently without notifying listeners
     */
    clearFilter : function(suppressEvent){
        if(this.snapshot && this.snapshot != this.data){
            this.data = this.snapshot;
            delete this.snapshot;
            if(suppressEvent !== true){
                this.fireEvent("datachanged", this);
            }
        }
    },

    // private
    afterEdit : function(record){
        if(this.modified.indexOf(record) == -1){
            this.modified.push(record);
        }
        this.fireEvent("update", this, record, Ext.data.Record.EDIT);
    },

    // private
    afterReject : function(record){
        this.modified.remove(record);
        this.fireEvent("update", this, record, Ext.data.Record.REJECT);
    },

    // private
    afterCommit : function(record){
        this.modified.remove(record);
        this.fireEvent("update", this, record, Ext.data.Record.COMMIT);
    },

    /**
     * Commit all Records with outstanding changes. To handle updates for changes, subscribe to the
     * Store's "update" event, and perform updating when the third parameter is Ext.data.Record.COMMIT.
     */
    commitChanges : function(){
        var m = this.modified.slice(0);
        this.modified = [];
        for(var i = 0, len = m.length; i < len; i++){
            m[i].commit();
        }
    },

    /**
     * Cancel outstanding changes on all changed records.
     */
    rejectChanges : function(){
        var m = this.modified.slice(0);
        this.modified = [];
        for(var i = 0, len = m.length; i < len; i++){
            m[i].reject();
        }
    },

    onMetaChange : function(meta, rtype, o){
        this.recordType = rtype;
        this.fields = rtype.prototype.fields;
        delete this.snapshot;
        this.sortInfo = meta.sortInfo;
        this.modified = [];
        this.fireEvent('metachange', this, this.reader.meta);
    }
});