/**
 * @author Ed Spencer
 * @class Ext.data.Association
 * @extends Object
 * 
 * 
Associations enable you to express relationships between different {@link Ext.data.Model Models}. Let's say we're
 * writing an ecommerce system where Users can make Orders - there's a relationship between these Models that we can
 * express like this:
 * 

Ext.regModel('User', {
    fields: ['id', 'name', 'email'],

    hasMany: {model: 'Order', name: 'orders'}
});

Ext.regModel('Order', {
    fields: ['id', 'user_id', 'status', 'price'],

    belongsTo: 'User'
});

 * 
 * 
We've set up two models - User and Order - and told them about each other. You can set up as many associations on
 * each Model as you need using the two default types - {@link Ext.data.HasManyAssociation hasMany} and 
 * {@link Ext.data.BelongsToAssociation belongsTo}. There's much more detail on the usage of each of those inside their
 * documentation pages. If you're not familiar with Models already, {@link Ext.data.Model there is plenty on those too}.
 * 
 * 
Further Reading
 * 
 * 

 *   
{@link Ext.data.HasManyAssociation hasMany associations}
 *   
{@link Ext.data.BelongsToAssociation belongsTo associations}
 *   
{@link Ext.data.Model using Models}
 * 
 * 
 * @constructor
 * @param {Object} config Optional config object
 */
Ext.define('Ext.data.Association', {
    
/**
     * @cfg {String} ownerModel The string name of the model that owns the association. Required
     */
    
    
/**
     * @cfg {String} associatedModel The string name of the model that is being associated with. Required
     */
    
    
/**
     * @cfg {String} primaryKey The name of the primary key on the associated model. Defaults to 'id'
     */
    primaryKey: 'id',
    
    constructor: function(config) {
        Ext.apply(this, config);
        
        var types           = Ext.ModelMgr.types,
            ownerName       = config.ownerModel,
            associatedName  = config.associatedModel,
            ownerModel      = types[ownerName],
            associatedModel = types[associatedName],
            ownerProto;
        
        if (ownerModel === undefined) {
            throw new Error("The configured ownerModel was not valid (you tried " + ownerName + ")");
        }
        
        if (associatedModel === undefined) {
            throw new Error("The configured associatedModel was not valid (you tried " + associatedName + ")");
        }
        
        this.ownerModel = ownerModel;
        this.associatedModel = associatedModel;
        
        
/**
         * The name of the model that 'owns' the association
         * @property ownerName
         * @type String
         */
        
        
/**
         * The name of the model is on the other end of the association (e.g. if a User model hasMany Orders, this is 'Order')
         * @property associatedName
         * @type String
         */
        
        Ext.applyIf(this, {
            ownerName : ownerName,
            associatedName: associatedName
        });
    }
});