Ext.data.HasManyAssociation

Hierarchy
Ext.data.Association
Ext.data.HasManyAssociation

Represents a one-to-many relationship between two models. Usually created indirectly via a model definition:

Ext.define('Product', {
    extend: 'Ext.data.Model',
    fields: [
        {name: 'id',      type: 'int'},
        {name: 'user_id', type: 'int'},
        {name: 'name',    type: 'string'}
    ]
});

Ext.define('User', {
    extend: 'Ext.data.Model',
    fields: [
        {name: 'id',   type: 'int'},
        {name: 'name', type: 'string'}
    ],
    // we can use the hasMany shortcut on the model to create a hasMany association
    hasMany: {model: 'Product', name: 'products'}
});

Above we created Product and User models, and linked them by saying that a User hasMany Products. This gives us a new function on every User instance, in this case the function is called 'products' because that is the name we specified in the association configuration above.

This new function returns a specialized Store which is automatically filtered to load only Products for the given model instance:

//first, we load up a User with id of 1
var user = Ext.ModelManager.create({id: 1, name: 'Ed'}, 'User');

//the user.products function was created automatically by the association and returns a Store
//the created store is automatically scoped to the set of Products for the User with id of 1
var products = user.products();

//we still have all of the usual Store functions, for example it's easy to add a Product for this User
products.add({
    name: 'Another Product'
});

//saves the changes to the store - this automatically sets the new Product's user_id to 1 before saving
products.sync();

The new Store is only instantiated the first time you call products() to conserve memory and processing time, though calling products() a second time returns the same store instance.

Custom filtering

The Store is automatically furnished with a filter - by default this filter tells the store to only return records where the associated model's foreign key matches the owner model's primary key. For example, if a User with ID = 100 hasMany Products, the filter loads only Products with user_id == 100.

Sometimes we want to filter by another field - for example in the case of a Twitter search application we may have models for Search and Tweet:

Ext.define('Search', {
    extend: 'Ext.data.Model',
    fields: [
        'id', 'query'
    ],

    hasMany: {
        model: 'Tweet',
        name : 'tweets',
        filterProperty: 'query'
    }
});

Ext.define('Tweet', {
    extend: 'Ext.data.Model',
    fields: [
        'id', 'text', 'from_user'
    ]
});

//returns a Store filtered by the filterProperty
var store = new Search({query: 'Sencha Touch'}).tweets();

The tweets association above is filtered by the query property by setting the filterProperty, and is equivalent to this:

var store = new Ext.data.Store({
    model: 'Tweet',
    filters: [
        {
            property: 'query',
            value   : 'Sencha Touch'
        }
    ]
});

Ext.define('Group', {
    extend: 'Ext.data.Model',
    fields: ['id', 'name'],
    hasMany: 'User'
});

Ext.define('User', {
    extend: 'Ext.data.Model',
    fields: ['id', 'name', 'group_id'], // refers to the id of the group that this user belongs to
    belongsTo: 'Group'
});

// This will create a users() method on any Group model instance
Ext.define('Group', {
    extend: 'Ext.data.Model',
    fields: ['id', 'name'],
    hasMany: 'User'
});
var group = new Group();
console.log(group.users());

// The method to retrieve the users will now be getUserList
Ext.define('Group', {
    extend: 'Ext.data.Model',
    fields: ['id', 'name'],
    hasMany: {model: 'User', name: 'getUserList'}
});
var group = new Group();
console.log(group.getUserList());

associations: [{
    type: 'hasMany',
    model: 'User'
}]