ExtJS4：何时使用完整命名空间VS只是对象名称（模型关联）

    Ext.define(\'DnD.model.Item\', {
        extend: \'Ext.data.Model\',
        idProperty:\'item_number\',
        associations: [{
            type: \'belongsTo\',
            model: \'Company\',
            primaryKey: \'id\',
            foreignKey: \'company_id\',
            autoLoad: true
        }],
        proxy: {
            type: \'ajax\',
            url: \'data/items.json\',
            reader: {
                type: \'json\',
                root: \'items\',
                idProperty:\'id\'
            }
        },
        fields: [{
            name: \'id\',
            type: \'int\'
        },{
            name: \'box_number\',
            type: \'float\'
        }, {
            name: \'item_number\',
            type: \'float\'
        }, {
            name: \'name\',
            type: \'string\'
        },{
            name: \'format\',
            type: \'int\'
        }, {
            name: \'company_id\',
            type: \'int\'
        }, {
...

Ext.define(\'DnD.model.Company\', {
    extend: \'Ext.data.Model\',
    associations: [{
        type: \'hasMany\',
        model: \'Item\',
        primaryKey: \'id\',
        foreignKey: \'company_id\',
        autoLoad: true
    }],
    idProperty:\'id\',
    fields: [{
        name: \'id\',
        type: \'int\'
    }, {
        name: \'name\',
        type: \'string\'
    }],
    proxy: {
        type: \'ajax\',
        url: \'data/companies.json\',
        reader: {
            successProperty: true,
            type: \'json\',
            root: \'companies\',
            idProperty:\'id\'
        }
    }
})

Ext.Loader.setConfig({
    enabled: true,
    paths: {
        Ext: \'extjs/src\',
        My: \'app\'
    }
});
Ext.application({
    name: \'DnD\',
    appFolder: \'app\',
    autoCreateViewport: false,
    controllers: [
        \'Collections\',
        \'Items\'
    ],
    launch: function() {      
        this.viewport = Ext.create(\'DnD.view.Viewport\', {});
        this.viewport.show();        
    }
});

myItem.getCompany()

DnD.model.Company

Company

getDnD.model.Company()

getCompany()

Ext.define(\'DnD.controller.Collections\', {
    extend: \'Ext.app.Controller\',
    models: [
        \'Collection\'
    ],
    stores: [
        \'Collections\',
    ],
    views:[
        \'collection.List\'
    ],
    refs: [{
        ref: \'collectionList\', 
        selector: \'collectionlist\'
    }],    
    init: function() {
    }
});