Ext.data.Association

Associations enable you to express relationships between different 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.define('User', {
-    extend: 'Ext.data.Model',
-    fields: ['id', 'name', 'email'],
-
-    hasMany: {model: 'Order', name: 'orders'}
-});
-
-Ext.define('Order', {
-    extend: 'Ext.data.Model',
-    fields: ['id', 'user_id', 'status', 'price'],
-
-    belongsTo: 'User'
-});
-

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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 - hasMany and -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, there is plenty on those too.

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Further Reading

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Self association models

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We can also have models that create parent/child associations between the same type. Below is an example, where -groups can be nested inside other groups:

- - -


-// Server Data
-{
-    "groups": {
-        "id": 10,
-        "parent_id": 100,
-        "name": "Main Group",
-        "parent_group": {
-            "id": 100,
-            "parent_id": null,
-            "name": "Parent Group"
-        },
-        "child_groups": [{
-            "id": 2,
-            "parent_id": 10,
-            "name": "Child Group 1"
-        },{
-            "id": 3,
-            "parent_id": 10,
-            "name": "Child Group 2"
-        },{
-            "id": 4,
-            "parent_id": 10,
-            "name": "Child Group 3"
-        }]
-    }
-}
-
-// Client code
-Ext.define('Group', {
-    extend: 'Ext.data.Model',
-    fields: ['id', 'parent_id', 'name'],
-    proxy: {
-        type: 'ajax',
-        url: 'data.json',
-        reader: {
-            type: 'json',
-            root: 'groups'
-        }
-    },
-    associations: [{
-        type: 'hasMany',
-        model: 'Group',
-        primaryKey: 'id',
-        foreignKey: 'parent_id',
-        autoLoad: true,
-        associationKey: 'child_groups' // read child data from child_groups
-    }, {
-        type: 'belongsTo',
-        model: 'Group',
-        primaryKey: 'id',
-        foreignKey: 'parent_id',
-        autoLoad: true,
-        associationKey: 'parent_group' // read parent data from parent_group
-    }]
-});
-
-
-Ext.onReady(function(){
-    
-    Group.load(10, {
-        success: function(group){
-            console.log(group.getGroup().get('name'));
-            
-            group.groups().each(function(rec){
-                console.log(rec.get('name'));
-            });
-        }
-    });
-    
-});
-

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Defined By