Hierarchy
Ext.data.AssociationExt.data.BelongsToAssociation
Represents a many to one association with another model. The owner model is expected to have a foreign key which references the primary key of the associated model:
Ext.define('Category', {
extend: 'Ext.data.Model',
fields: [
{name: 'id', type: 'int'},
{name: 'name', type: 'string'}
]
});
Ext.define('Product', {
extend: 'Ext.data.Model',
fields: [
{name: 'id', type: 'int'},
{name: 'category_id', type: 'int'},
{name: 'name', type: 'string'}
],
// we can use the belongsTo shortcut on the model to create a belongsTo association
belongsTo: {type: 'belongsTo', model: 'Category'}
});
In the example above we have created models for Products and Categories, and linked them together by saying that each Product belongs to a Category. This automatically links each Product to a Category based on the Product's category_id, and provides new functions on the Product model:
Generated getter function
The first function that is added to the owner model is a getter function:
var product = new Product({
id: 100,
category_id: 20,
name: 'Sneakers'
});
product.getCategory(function(category, operation) {
//do something with the category object
alert(category.get('id')); //alerts 20
}, this);
The getCategory function was created on the Product model when we defined the association. This uses the Category's configured proxy to load the Category asynchronously, calling the provided callback when it has loaded.
The new getCategory function will also accept an object containing success, failure and callback properties - callback will always be called, success will only be called if the associated model was loaded successfully and failure will only be called if the associatied model could not be loaded:
product.getCategory({
callback: function(category, operation) {}, //a function that will always be called
success : function(category, operation) {}, //a function that will only be called if the load succeeded
failure : function(category, operation) {}, //a function that will only be called if the load did not succeed
scope : this //optionally pass in a scope object to execute the callbacks in
});
In each case above the callbacks are called with two arguments - the associated model instance and the operation object that was executed to load that instance. The Operation object is useful when the instance could not be loaded.
Generated setter function
The second generated function sets the associated model instance - if only a single argument is passed to the setter then the following two calls are identical:
//this call
product.setCategory(10);
//is equivalent to this call:
product.set('category_id', 10);
If we pass in a second argument, the model will be automatically saved and the second argument passed to the owner model's save method:
product.setCategory(10, function(product, operation) {
//the product has been saved
alert(product.get('category_id')); //now alerts 10
});
//alternative syntax:
product.setCategory(10, {
callback: function(product, operation), //a function that will always be called
success : function(product, operation), //a function that will only be called if the load succeeded
failure : function(product, operation), //a function that will only be called if the load did not succeed
scope : this //optionally pass in a scope object to execute the callbacks in
})
Customisation
Associations reflect on the models they are linking to automatically set up properties such as the primaryKey and foreignKey. These can alternatively be specified:
Ext.define('Product', {
fields: [...],
associations: [
{type: 'belongsTo', model: 'Category', primaryKey: 'unique_id', foreignKey: 'cat_id'}
]
});
Here we replaced the default primary key (defaults to 'id') and foreign key (calculated as 'category_id') with our own settings. Usually this will not be needed.
The string name of the model that is being associated with. Required
The string name of the model that is being associated with. Required
The name of the property in the data to read the association from. Defaults to the name of the associated model.
The name of the property in the data to read the association from. Defaults to the name of the associated model.
The name of the foreign key on the owner model that links it to the associated model. Defaults to the lowercased name of the associated model plus "_id", e.g. an association with a model called Product would set up a product_id foreign key.
Ext.define('Order', {
extend: 'Ext.data.Model',
fields: ['id', 'date'],
hasMany: 'Product'
});
Ext.define('Product', {
extend: 'Ext.data.Model',
fields: ['id', 'name', 'order_id'], // refers to the id of the order that this product belongs to
belongsTo: 'Group'
});
var product = new Product({
id: 1,
name: 'Product 1',
order_id: 22
}, 1);
product.getOrder(); // Will make a call to the server asking for order_id 22
The name of the getter function that will be added to the local model's prototype. Defaults to 'get' + the name of the foreign model, e.g. getCategory
The string name of the model that owns the association. Required
The string name of the model that owns the association. Required
The name of the primary key on the associated model. Defaults to 'id'. In general this will be the Ext.data.Model.idProperty of the Model.
The name of the setter function that will be added to the local model's prototype. Defaults to 'set' + the name of the foreign model, e.g. setCategory
The type configuration can be used when creating associations using a configuration object. Use 'belongsTo' to create a HasManyAssocation
associations: [{
type: 'belongsTo',
model: 'User'
}]
The name of the model is on the other end of the association (e.g. if a User model hasMany Orders, this is 'Order')
The name of the model is on the other end of the association (e.g. if a User model hasMany Orders, this is 'Order')