Gallery

YUI({
    //Last Gallery Build of this module
    gallery: 'gallery-2012.09.05-20-01'
}).use('gallery-md-model','json', function(Y) {
    var MyModel = Y.Base.create(
        'my-model',
        Y.GalleryModel,
        [],
        {
            sync: function (action, options, callback) {
                switch (action) {
                    case 'read':
                        callback(null, Y.merge({fieldOne: 1, fieldTwo: 2}, options));
                        break;
                    case 'create':
                    case 'update':
                    case 'delete':
                        callback(null);
                        break;
                    default:
                        callback('operation not allowed');
                        break;
                }
            },
            // Method toJSON() is originally set to call method getValues()
            // Having toJSON() separate from getValues() allows redefining toJSON()
            // without messing up getValues()
            toJSON: function() {
                return {
                    // getPKValues() (PK: primary key) returns an object with the values for the primary key(s)
                    keys: this.getPKValues(),
                    // getChangeValues() returns an object with the previous and new values 
                    // for all fields changed since last synched with the remote source
                    values: this.getChangedValues()
                };
            }
        },
        {
            ATTRS: {
                // primaryKeys is now an attribute and can take multiple fields
                // If only one, a single string (not an array) can be provided
                primaryKeys: {
                    value: ['primaryKey1', 'primaryKey2']
                }
            }
        }
    );
    var myModel = new MyModel();
 
    // isNew and isModified are now attributes
    console.log('new model', myModel.get('isNew'), myModel.get('isModified'));
    // should show: "new model true false"
 
    myModel.load({primaryKey1: 12, primaryKey2: 34}, function(err, response) {
        console.log('loaded model', myModel.get('isNew'), myModel.get('isModified'));
        // should show: "loaded model false false"
 
        // Field values are read/set via getValue/setValue methods
        console.log('fieldOne: ', myModel.getValue('fieldOne'));
        // should show: "fieldOne: 1"
 
        myModel.setValue('fieldOne', 3);
 
        // You can query the status of individual fields or the whole record
        console.log('fieldOne status: ', myModel.get('isNew.fieldOne'),myModel.get('isModified.fieldOne'));
        // should show: "fieldOne status: false true"
        console.log('fieldTwo status: ', myModel.get('isNew.fieldTwo'),myModel.get('isModified.fieldTwo'));
        // should show: "fieldTwo status: false false"
        console.log('record status: ', myModel.get('isNew'), myModel.get('isModified'));
        // should show: "record status: false true"
 
        console.log('Stringified record', Y.JSON.stringify(myModel));                    
        // should show: "Stringified record {"keys":{"primaryKey1":12,"primaryKey2":34},"values":{"fieldOne":{"prevVal":1,"newVal":3}}}"
        /*
        Having the previous value for the changed field allows for building SQL statements such as:
            UPDATE myTable set fieldOne = 3 where primaryKey1 = 12 and primaryKey2 = 34 and fieldOne = 1
        The last conditional ensures that the modification is applied 
        only if the field to be changed has not been modified by other user
        */
 
        // The following will fail:
        myModel.setValue('primaryKey1', 'whatever');
        // primary keys cannot be modified
 
        // The change event listener can serve to reject or modify a value being set
        myModel.on('change', function (ev) {
            switch (ev.name) {
                // fieldOne will have its values doubled
                case 'fieldOne':
                    ev.newVal *= 2;
                    break;
                // fieldTwo will reject even values
                case 'fieldTwo':
                     if (ev.newVal === Math.floor(ev.newVal / 2) * 2) {
                         ev.halt();
                     }
                    break;
            }
        });
        myModel.setValue('fieldOne', 7);
        console.log('fieldOne=7 doubled: ', myModel.getValue('fieldOne'));
        // should show: "fieldOne=7 doubled: 14"
        myModel.setValue('fieldTwo', 7);
        console.log('fieldTwo=7 accepted: ', myModel.getValue('fieldTwo'));
        // should show: "fieldTwo=7 accepted: 7"
        myModel.setValue('fieldTwo', 6);
        console.log('fieldTwo=6 rejected: ', myModel.getValue('fieldTwo'));
        // should show: "fieldTwo=6 rejected: 7"
 
 
        // There is also a multiple record extension with optiona sorting
        var MultiRecordModel = Y.Base.create('multi-record', Y.GalleryModel, 
              [Y.GalleryModelMultiRecord, Y.GalleryModelSortedMultiRecord]),
            multiModel = new MultiRecordModel({primaryKeys: 'primaryKeyField'}),
            i;
 
        for (i = 0; i < 20; i += 1) {
            multiModel.add({primaryKeyField: Math.floor(Math.random() * 9999), fieldOne:i});
        }
        console.log('Values should show in ascending order');
        // Method each makes each record current and provides the index for it
        // By default the first primary key field is the sort field, in ascending order
        multiModel.each(function(index) {
            console.log(index, multiModel.getValue('primaryKeyField'));
        });
 
        console.log('Values should now show in descending order');
        multiModel.set('sortDir', 'desc');
        multiModel.each(function(index) {
            console.log(index, multiModel.getValue('primaryKeyField'));
        });
        // The sort field needs not be the primary key
        multiModel.setAttrs({sortField:'fieldOne', sortDir:'asc'});
 
        // As you can guess, the records would now show sorted by field one
 
        // You can go to any record
        multiModel.set('index',5);
        // if you modify a sorted field, it will relocate itself to its proper place
        multiModel.setValue('fieldOne', 1.5 );
        // Now, it should no longer be at position 5 (the sixth counting from zero) but at position 2
        console.log('The current record is now: ', multiModel.get('index'));
 
        // lets pretend we save the records at odd indexes
        multiModel.each(function (index) {
            if (index & 1) {
                 multiModel.save();
             }
        });
 
        // Though there are no provisions to save batches of records
        // if the load() method gets an array of records instead of a single record
        // it will load them each in its own shelf
 
        // You can also loop only through modified records (makes it easy to save them)
        // Only even ones should remain modified
        multiModel.eachModified(function (index) {
            console.log('Modified record at:', index);
        });
 
        // You can search a record by the value, on sorted columns 
        // The find method returns the index at which a particular value is found
        console.log('Record with value 2 is now at position: ', multiModel.find(2, false));
        // By adding the second, false, argument, the model will not be positioned at that record.
        // The default is to get positioned.
 
 
        console.log('The model contains: ', multiModel.size());
        multiModel.empty();
        console.log('The model contains none: ', multiModel.size());
 
 
    });
});