This package provides support for sub-models that can be treated much like belongsTo and hasMany relationships are, but whose persistence is managed completely through the parent object.
Use the following table to decide which version of this project to use with your app:
| Ember Data | Model Fragments |
|---|---|
| > v1.0.0-beta.7 <= v1.0.0-beta.11 | v0.2.3 |
| v1.0.0-beta.14 | v0.2.8 |
| >= v1.0.0-beta.15 <= v1.0.0-beta.18 | v0.3.3 |
| >= v1.13.x | >= v0.4.0 |
To install as an Ember CLI addon:
$ ember install ember-data-model-fragmentsYou may then start creating fragments with:
$ ember generate fragment foo someAttr:string anotherAttr:booleanWhich will create the module app/models/foo.js which exports a DS.ModelFragment class with the given attributes.
App.Person = DS.Model.extend({
name : DS.hasOneFragment('name'),
addresses : DS.hasManyFragments('address'),
titles : DS.hasManyFragments()
});
App.Name = DS.ModelFragment.extend({
first : DS.attr('string'),
last : DS.attr('string')
});
App.Address = DS.ModelFragment.extend({
street : DS.attr('string'),
city : DS.attr('string'),
region : DS.attr('string'),
country : DS.attr('string')
});With a JSON payload of:
{
"id": "1",
"name": {
"first": "Tyrion",
"last": "Lannister"
},
"addresses": [
{
"street": "1 Sky Cell",
"city": "Eyre",
"region": "Vale of Arryn",
"country": "Westeros"
},
{
"street": "1 Tower of the Hand",
"city": "King's Landing",
"region": "Crownlands",
"country": "Westeros"
}
],
"titles": [ "Imp", "Hand of the King" ]
}The name attribute can be treated similar to a belongsTo relationship:
var person = store.getById('person', '1');
var name = person.get('name');
person.get('isDirty'); // false
name.get('first'); // 'Tyrion'
name.set('first', 'Jamie');
person.get('isDirty'); // true
person.rollback();
name.get('first'); // 'Tyrion'
// New fragments are created through the store and assigned directly
person.set('name', store.createFragment('name', {
first : 'Hugor',
last : 'Hill'
}));
person.get('isDirty'); // trueThe addresses attribute can be treated similar to a hasMany relationship:
var person = store.getById('person', '1');
var addresses = person.get('addresses');
var address = addresses.get('lastObject');
person.get('isDirty'); // false
address.get('country'); // 'Westeros'
address.set('country', 'Essos');
person.get('isDirty'); // true
person.rollback();
address.get('country'); // 'Westeros'
// Fragments can be created and added directly through the fragment array
addresses.get('length'); // 2
addresses.createFragment({
street : '1 Shy Maid',
city : 'Rhoyne River',
region : 'Free Cities',
country : 'Essos'
});
addresses.get('length'); // 3
person.get('isDirty'); // trueThe titles attribute can be treated as an Ember.Array:
var person = store.getById('person', '1');
var titles = person.get('titles');
person.get('isDirty'); // false
titles.get('length'); // 2
titles.pushObject('Halfman');
titles.get('length'); // 3
person.get('isDirty'); // true
person.rollback();
titles.get('length'); // 2Ember Data attributes support a defaultValue config option that provides a default value when a model is created through store#createRecord(). Similarly, DS.hasOneFragment and DS.hasManyFragments properties support a defaultValue option:
App.Person = DS.Model.extend({
name : DS.hasOneFragment('name', { defaultValue: { first: 'Faceless', last: 'Man' } }),
addresses : DS.hasManyFragments('address', { defaultValue: [] }),
titles : DS.hasManyFragments(null, { defaultValue: [] })
});Since JavaScript objects and arrays are passed by reference, the value of defaultValue is copied using Ember.copy in order to prevent all instances sharing the same value. If a defaultValue option is not specified, both DS.hasOneFragment and DS.hasManyFragments properties will default to null. Note that this may cause confusion when creating a record with a DS.hasManyFragments property:
var person = store.createRecord('person');
var addresses = person.get('addresses'); // null
// Fails with "Cannot read property 'createFragment' of null"
addresses.createFragment({
...
});Like DS.attr, the defaultValue option can be a function that is invoked to generate the default value:
App.Person = DS.Model.extend({
name: DS.hasOneFragment('name', {
defaultValue: function() {
return {
first: 'Unsullied',
last: Ember.uuid()
}
}
})
});Serializing records with fragment attributes works using a special DS.Transform that serializes each fragment or fragment array. This results in fragments being nested in JSON as expected, and avoids the need for any custom serialization logic for most cases. This also means that model fragments can have their own custom serializers, just as normal models can:
App.Name = DS.ModelFragment.extend({
given : DS.attr('string'),
family : DS.attr('string')
});
// Serializers for fragments work just as with models
App.NameSerializer = DS.JSONSerializer.extend({
attrs: {
given : 'first',
family : 'last'
}
});If custom serialization of the owner record is needed, fragment snapshots can be accessed using the Snapshot#attr method. Note that this differs from how relationships are accessed on snapshots (using belongsTo/hasMany methods):
// Fragment snapshots are accessed using `snapshot.attr()`
App.PersonSerializer = DS.JSONSerializer.extend({
serialize: function(snapshot, options) {
var json = this._super(snapshot, options);
// Returns a `DS.Snapshot` instance of the fragment
var nameSnapshot = snapshot.attr('name');
json.full_name = nameSnapshot.attr('given') + ' ' + nameSnapshot.attr('family');
// Returns a plain array of `DS.Snapshot` instances
var addressSnapshots = snapshot.attr('addresses');
json.countries = addressSnapshots.map(function(addressSnapshot) {
return addressSnapshot.attr('country');
});
// Returns a plain array of primitives
var titlesSnapshot = snapshot.attr('titles');
json.title_count = titlesSnapshot.length;
return json;
}
});Nesting of fragments is fully supported:
App.User = DS.Model.extend({
name : DS.attr('string'),
orders : DS.hasManyFragments('order')
});
App.Order = DS.ModelFragment.extend({
amount : DS.attr('string'),
products : DS.hasManyFragments('product')
});
App.Product = DS.ModelFragment.extend({
name : DS.attr('string'),
sku : DS.attr('string'),
price : DS.attr('string')
});With a JSON payload of:
{
"id": "1",
"name": "Tyrion Lannister",
"orders": [
{
"amount": "799.98",
"products" : [
{
"name": "Tears of Lys",
"sku": "poison-bd-32",
"price": "499.99"
},
{
"name": "The Strangler",
"sku": "poison-md-24",
"price": "299.99"
}
]
},
{
"amount": "10999.99",
"products": [
{
"name": "Lives of Four Kings",
"sku": "old-book-32",
"price": "10999.99"
}
]
}
]
}Dirty state propagates up to the parent record, rollback cascades down:
var user = store.getById('user', '1');
var product = user.get('orders.firstObject.products.lastObject');
user.get('isDirty'); // false
product.get('price'); // '299.99'
product.set('price', '1.99');
user.get('isDirty'); // true
user.rollback();
user.get('isDirty'); // false
product.get('price'); // '299.99'However, note that fragments do not currently support DS.belongsTo or DS.hasMany properties. See the Limitations section below.
Ember Data: Model Fragments has support for reading polymorphic fragments. To use this feature, pass an options object to hasOneFragment or hasManyFragments
with polymorphic set to true. In addition the typeKey can be set, which defaults to 'type'.
The typeKey's value must be the lowercase name of a class that is assignment-compatible to the declared type of the fragment attribute. That is, it must be the declared type itself or a subclass.
In the following example the declared type of animals is animal, which corresponds to the class App.Animal. App.Animal has two subclasses: App.Elephant and App.Lion,
so to typeKey's value can be 'animal', 'elephant' or 'lion'.
App.Zoo = DS.Model.extend({
name: DS.attr("string"),
city: DS.attr("string"),
animals: DS.hasManyFragments("animal", { polymorphic: true, typeKey: '$type' }),
});
App.Animal = DS.ModelFragment.extend({
name: DS.attr("string"),
});
App.Elephant = Animal.extend({
trunkLength: DS.attr("number"),
});
App.Lion = Animal.extend({
hasManes: DS.attr("boolean"),
});The expected JSON payload is as follows:
{
"Zoo" : {
"id" : "1",
"name" : "Winterfell Zoo",
"city" : "Winterfell",
"animals" : [
{
"$type" : "lion",
"name" : "Simba",
"hasManes" : false
},
{
"$type" : "lion",
"name" : "Leonard",
"hasManes" : true
},
{
"$type" : "elephant",
"name" : "Trunky",
"trunkLength" : 10
},
{
"$type" : "elephant",
"name" : "Snuffles",
"trunkLength" : 9
}
]
}
}Serializing the fragment type back to JSON is not currently supported out of the box. To serialize the polymorphic type, create a custom serializer to perform manual introspection:
App.AnimalSerializer = DS.JSONSerializer.extend({
serialize: function(record, options) {
var json = this._super(record, options);
if (record instanceof App.Elephant) {
json.$type = 'elephant';
} else if (record instanceof App.Lion) {
json.$type = 'lion';
} else {
json.$type = 'animal';
}
return json;
}
});
App.ElephantSerializer = App.AnimalSerializer;
App.LionSerializer = App.AnimalSerializer;There is a very good reason that support for id-less embedded records has not been added to Ember Data: merging conflicts is very difficult. Imagine a scenario where your app requests a record with an array of simple embedded objects, and then a minute later makes the same request again. If the array of objects has changed – for instance an object is added to the beginning – without unique identifiers there is no reliable way to map those objects onto the array of records in memory.
This plugin handles merging fragment arrays by swapping out the data of existing fragments. For example, when a record is fetched with a fragment array property, a fragment model is created for each object in the array. Then, after the record is reloaded via reload or save, the data received is mapped directly onto those existing fragment instances, adding or removing from the end when necessary. This means that reordering the array will cause fragment objects' data to swap, rather than simply reordering the array of fragments in memory. The biggest implication of this behavior is when a fragment in a fragment array is dirty and the parent model gets reloaded. If the record is then saved, the change will likely affect the wrong object, causing data loss. Additionally, any time a reference to a model fragment is held onto, reloading can give it a completely different semantic meaning. If your app does not persist models with fragment arrays, this is of no concern (and indeed you may wish to use the DS.EmbeddedRecordMixin instead).
Another consequence of id-less records is that an ID map of all fragment instances of a given type is not possible. This means no store.all('<fragment_type>'), and no ability to display all known fragments (e.g. names or addresses) without iterating over all owner records and manually building a list.
Currently, fragments cannot have normal DS.belongsTo or DS.hasMany relationships. This is not a technical limitation, but rather due to the fact that relationship management in Ember Data is in a state of flux and would require accessing private (and changing) APIs.
Building requires Ember CLI and running tests requires Test 'Em and Bower, which can all be installed globally with:
$ npm install --global ember-cli bower testemThen install NPM & Bower packages, build the project, and start the development test server:
$ npm install && bower install
$ ember build
$ testemIf you encounter test errors, ensure that your global testem NPM package is up to date.
When developing, it is often convenient to build the project with ember serve which will watch for file changes and rebuild, which triggers the test runner to re-run tests. A production build with debugging aids stripped out can also be made by running:
$ ember build --environment=productionWhen reporting an issue, follow the Ember guidelines. When contributing features, follow Github guidelines for forking and creating a new pull request. All existing tests must pass (or be suitably modified), and all new features must be accompanied by tests to be considered.
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