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<pre class="prettyprint lang-js"><span id='Ext-data-association-BelongsTo'>/**
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</span> * @author Ed Spencer
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* @class Ext.data.association.BelongsTo
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*
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* Represents a many to one association with another model. The owner model is expected to have
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* a foreign key which references the primary key of the associated model:
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*
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* Ext.define('Category', {
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* extend: 'Ext.data.Model',
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* fields: [
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* { name: 'id', type: 'int' },
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* { name: 'name', type: 'string' }
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* ]
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* });
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*
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* Ext.define('Product', {
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* extend: 'Ext.data.Model',
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* fields: [
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* { name: 'id', type: 'int' },
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* { name: 'category_id', type: 'int' },
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* { name: 'name', type: 'string' }
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* ],
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* // we can use the belongsTo shortcut on the model to create a belongsTo association
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* associations: [
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* { type: 'belongsTo', model: 'Category' }
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* ]
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* });
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*
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* In the example above we have created models for Products and Categories, and linked them together
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* by saying that each Product belongs to a Category. This automatically links each Product to a Category
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* based on the Product's category_id, and provides new functions on the Product model:
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*
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* ## Generated getter function
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*
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* The first function that is added to the owner model is a getter function:
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*
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* var product = new Product({
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* id: 100,
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* category_id: 20,
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* name: 'Sneakers'
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* });
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*
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* product.getCategory(function(category, operation) {
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* // do something with the category object
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* alert(category.get('id')); // alerts 20
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* }, this);
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*
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* The getCategory function was created on the Product model when we defined the association. This uses the
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* Category's configured {@link Ext.data.proxy.Proxy proxy} to load the Category asynchronously, calling the provided
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* callback when it has loaded.
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*
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* The new getCategory function will also accept an object containing success, failure and callback properties
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* - callback will always be called, success will only be called if the associated model was loaded successfully
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* and failure will only be called if the associatied model could not be loaded:
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*
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* product.getCategory({
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* reload: true, // force a reload if the owner model is already cached
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* callback: function(category, operation) {}, // a function that will always be called
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* success : function(category, operation) {}, // a function that will only be called if the load succeeded
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* failure : function(category, operation) {}, // a function that will only be called if the load did not succeed
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* scope : this // optionally pass in a scope object to execute the callbacks in
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* });
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*
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* In each case above the callbacks are called with two arguments - the associated model instance and the
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* {@link Ext.data.Operation operation} object that was executed to load that instance. The Operation object is
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* useful when the instance could not be loaded.
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*
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* Once the getter has been called on the model, it will be cached if the getter is called a second time. To
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* force the model to reload, specify reload: true in the options object.
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*
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* ## Generated setter function
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*
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* The second generated function sets the associated model instance - if only a single argument is passed to
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* the setter then the following two calls are identical:
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*
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* // this call...
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* product.setCategory(10);
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*
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* // is equivalent to this call:
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* product.set('category_id', 10);
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*
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* An instance of the owner model can also be passed as a parameter.
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*
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* If we pass in a second argument, the model will be automatically saved and the second argument passed to
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* the owner model's {@link Ext.data.Model#save save} method:
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*
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* product.setCategory(10, function(product, operation) {
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* // the product has been saved
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* alert(product.get('category_id')); //now alerts 10
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* });
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*
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* //alternative syntax:
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* product.setCategory(10, {
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* callback: function(product, operation), // a function that will always be called
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* success : function(product, operation), // a function that will only be called if the load succeeded
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* failure : function(product, operation), // a function that will only be called if the load did not succeed
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* scope : this //optionally pass in a scope object to execute the callbacks in
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* })
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*
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* ## Customisation
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*
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* Associations reflect on the models they are linking to automatically set up properties such as the
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* {@link #primaryKey} and {@link #foreignKey}. These can alternatively be specified:
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*
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* Ext.define('Product', {
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* fields: [...],
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*
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* associations: [
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* { type: 'belongsTo', model: 'Category', primaryKey: 'unique_id', foreignKey: 'cat_id' }
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* ]
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* });
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*
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* Here we replaced the default primary key (defaults to 'id') and foreign key (calculated as 'category_id')
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* with our own settings. Usually this will not be needed.
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*/
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Ext.define('Ext.data.association.BelongsTo', {
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extend: 'Ext.data.association.Association',
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alternateClassName: 'Ext.data.BelongsToAssociation',
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alias: 'association.belongsto',
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<span id='Ext-data-association-BelongsTo-cfg-foreignKey'> /**
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</span> * @cfg {String} foreignKey The name of the foreign key on the owner model that links it to the associated
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* model. Defaults to the lowercased name of the associated model plus "_id", e.g. an association with a
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* model called Product would set up a product_id foreign key.
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*
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* Ext.define('Order', {
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* extend: 'Ext.data.Model',
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* fields: ['id', 'date'],
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* hasMany: 'Product'
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* });
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*
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* Ext.define('Product', {
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* extend: 'Ext.data.Model',
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* fields: ['id', 'name', 'order_id'], // refers to the id of the order that this product belongs to
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* belongsTo: 'Order'
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* });
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* var product = new Product({
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* id: 1,
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* name: 'Product 1',
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* order_id: 22
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* }, 1);
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* product.getOrder(); // Will make a call to the server asking for order_id 22
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*
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*/
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<span id='Ext-data-association-BelongsTo-cfg-getterName'> /**
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</span> * @cfg {String} getterName The name of the getter function that will be added to the local model's prototype.
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* Defaults to 'get' + the name of the foreign model, e.g. getCategory
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*/
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<span id='Ext-data-association-BelongsTo-cfg-setterName'> /**
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</span> * @cfg {String} setterName The name of the setter function that will be added to the local model's prototype.
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* Defaults to 'set' + the name of the foreign model, e.g. setCategory
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*/
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<span id='Ext-data-association-BelongsTo-cfg-type'> /**
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</span> * @cfg {String} type The type configuration can be used when creating associations using a configuration object.
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* Use 'belongsTo' to create a BelongsTo association.
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*
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* associations: [{
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* type: 'belongsTo',
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* model: 'User'
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* }]
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*/
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constructor: function(config) {
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this.callParent(arguments);
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var me = this,
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ownerProto = me.ownerModel.prototype,
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associatedName = me.associatedName,
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getterName = me.getterName || 'get' + associatedName,
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setterName = me.setterName || 'set' + associatedName;
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Ext.applyIf(me, {
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name : associatedName,
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foreignKey : associatedName.toLowerCase() + "_id",
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instanceName: associatedName + 'BelongsToInstance',
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associationKey: associatedName.toLowerCase()
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});
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ownerProto[getterName] = me.createGetter();
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ownerProto[setterName] = me.createSetter();
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},
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<span id='Ext-data-association-BelongsTo-method-createSetter'> /**
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</span> * @private
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* Returns a setter function to be placed on the owner model's prototype
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* @return {Function} The setter function
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*/
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createSetter: function() {
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var me = this,
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foreignKey = me.foreignKey,
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instanceName = me.instanceName;
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//'this' refers to the Model instance inside this function
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return function(value, options, scope) {
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// If we were passed a record, the value to set is the key of that record.
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var setByRecord = value && value.isModel,
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valueToSet = setByRecord ? value.getId() : value;
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// Setter was passed a record.
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if (setByRecord) {
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this[instanceName] = value;
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}
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// Otherwise, if the key of foreign record !== passed value, delete the cached foreign record
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else if (this[instanceName] instanceof Ext.data.Model && !this.isEqual(this.get(foreignKey), valueToSet)) {
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delete this[instanceName];
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}
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// Set the forign key value
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this.set(foreignKey, valueToSet);
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if (Ext.isFunction(options)) {
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options = {
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callback: options,
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scope: scope || this
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};
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}
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if (Ext.isObject(options)) {
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return this.save(options);
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}
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};
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},
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<span id='Ext-data-association-BelongsTo-method-createGetter'> /**
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</span> * @private
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* Returns a getter function to be placed on the owner model's prototype. We cache the loaded instance
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* the first time it is loaded so that subsequent calls to the getter always receive the same reference.
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* @return {Function} The getter function
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*/
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createGetter: function() {
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var me = this,
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associatedName = me.associatedName,
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associatedModel = me.associatedModel,
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foreignKey = me.foreignKey,
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primaryKey = me.primaryKey,
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instanceName = me.instanceName;
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//'this' refers to the Model instance inside this function
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return function(options, scope) {
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options = options || {};
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var model = this,
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foreignKeyId = model.get(foreignKey),
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success,
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instance,
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args;
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if (options.reload === true || model[instanceName] === undefined) {
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instance = Ext.ModelManager.create({}, associatedName);
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instance.set(primaryKey, foreignKeyId);
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if (typeof options == 'function') {
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options = {
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callback: options,
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scope: scope || model
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};
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}
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// Overwrite the success handler so we can assign the current instance
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success = options.success;
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options.success = function(rec){
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model[instanceName] = rec;
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if (success) {
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success.apply(this, arguments);
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}
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};
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associatedModel.load(foreignKeyId, options);
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// assign temporarily while we wait for data to return
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model[instanceName] = instance;
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return instance;
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} else {
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instance = model[instanceName];
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args = [instance];
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scope = scope || options.scope || model;
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//TODO: We're duplicating the callback invokation code that the instance.load() call above
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//makes here - ought to be able to normalize this - perhaps by caching at the Model.load layer
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//instead of the association layer.
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Ext.callback(options, scope, args);
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Ext.callback(options.success, scope, args);
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Ext.callback(options.failure, scope, args);
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Ext.callback(options.callback, scope, args);
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return instance;
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}
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};
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},
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<span id='Ext-data-association-BelongsTo-method-read'> /**
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</span> * Read associated data
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* @private
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* @param {Ext.data.Model} record The record we're writing to
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* @param {Ext.data.reader.Reader} reader The reader for the associated model
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* @param {Object} associationData The raw associated data
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*/
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read: function(record, reader, associationData){
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record[this.instanceName] = reader.read([associationData]).records[0];
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}
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});
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</pre>
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