SproutCore

SproutCore Guides

These guides are designed to help you write and perfect your code.

SproutCore Records

This guide covers the basics of SproutCore's model layer. By referring to this guide, you will be able to:

  • Understand the anatomy of records.
  • Define your application specific models and relations between them.
  • Create and manage records.
  • Understand how the store manages your data.
  • Query the store for data.

1 - Models, Records and the Store

In SproutCore the model layer is the lowest application layer and holds all your data as well as the business logic of your application. The controller layer calls into the model layer to modify data and retrieves data from the model layer. Generally, controllers use bindings to perform these functions.

The model layer is also responsible for talking to your server, fetching and committing data when necessary. The server communication aspect of the model layer is not covered in this guide, but in the guide about using data sources.

Models are a blueprint for your data, defining the data schema of your application. This data schema is generally similar to the data schema of your back-end application.

In SproutCore, models are defined by subclassing SC.Record. When you actually want to create a data record from one of your blueprints, you use SC.Store to create an instance of a SC.Record class. Your application's store manages the lifecycle and the data of your records in a central place. When you retrieve or update a property from a record, the record actually uses the store to access the underlying data hash.

All the classes of SproutCore's model layer are located in the datastore folder inside the main sproutcore folder. Have a look at the source code there if you want to have more in-depth information. The code has plenty of inline documentation and can be a valuable resource to gain deeper insights in how the store works.

2 - Anatomy of Records

A SproutCore record consists of four main components:

  • Store key
  • ID
  • Status
  • Data hash

Each record has a unique store key which is assigned when the record is created. The store key is a unique record identifier in the whole store and is used internally to relate IDs, statuses and data hashes to each other in an unambiguous way. The store key is the only one of the four components which is actually a property of SC.Record. The other three components are stored centrally in the store and mapped to the individual records using the store key.

Record Anatomy

All records of a given type have a unique ID, as usual in relational database systems. In fact the IDs of SproutCore records usually are the same as the primary keys of your data in the backend. Therefore, unlike the store key, the ID is not automatically created. Instead, it is your responsibility to assign a unique ID when creating or loading records.

The status of a record represents its current state with respect to the corresponding record on the server. The store uses the status property to determine which operations can be performed on the record, for instance, if a record can be edited safely and which records need to be committed back to the server.

Last but not least, the actual data of a record is stored in a plain JSON data hash. When you get or set a property on a record, the value of this property is read from or written to the data hash.

2.1 - Primary Record States

There are five primary record status codes in SproutCore:

  • SC.Record.EMPTY
  • SC.Record.READY
  • SC.Record.BUSY
  • SC.Record.DESTROYED
  • SC.Record.ERROR

The names of these states are pretty self explanatory: EMPTY indicates a non-existent record. READY indicates that the record can be safely edited.

BUSY indicates that the record is currently locked for write operations, mostly because of an ongoing communication with the server. Finally DESTROYED is the state of destroyed records and ERROR indicates that something went wrong while processing this record.

The three main states READY, BUSY and DESTROYED have several sub-states. You will learn more about these sub-states below when you actually start working with records. You can also refer to the complete overview of record states in the last section of this guide.

3 - Defining Your Models

Defining a model in SproutCore is as easy as subclassing SC.Record:

apps/app/models/contact.js
App.Contact = SC.Record.extend({ });

You just have created your custom App.Contact model class. However, this empty model is only of limited use, so let's add some record attributes.

apps/app/models/contact.js
App.Contact = SC.Record.extend({ firstName: SC.Record.attr(String), lastName: SC.Record.attr(String), age: SC.Record.attr(Number) });

Property names defined on SC.Record itself are reserved names, meaning they cannot be used for custom record attributes. Please refer to the documentation of SC.Record for a list of all reserved names.

We have used the SC.Record.attr helper to add the firstName, lastName and age attributes with the type of each attribute as first argument. The optional second argument of SC.Record.attr is an option hash. E.g. we can add some default values to our attributes:

apps/app/models/contact.js
App.Contact = SC.Record.extend({ firstName: SC.Record.attr(String, { defaultValue: 'Unspecified' }), lastName: SC.Record.attr(String, { defaultValue: 'Unspecified' }), age: SC.Record.attr(Number, { defaultValue: 0 }) });

Whenever you specify a defaultValue option on an attribute, it will return this default value if that attribute is null or undefined for a given instance.

The defaultValue will not be written to the underlying data hash and therefore not committed back to the server.

If the name of the model's attribute property differs from the name you want to use in the data hash, you can specify a custom key for each attribute which will be used to access the data hash:

apps/app/models/contact.js
App.Contact = SC.Record.extend({ firstName: SC.Record.attr(String, { key: 'first_name' }), lastName: SC.Record.attr(String, { key: 'last_name' }), age: SC.Record.attr(Number) });

3.1 - Attribute Types

All basic JavaScript data types can be used as attribute types:

  • String
  • Number
  • Boolean
  • Array
  • Object

Additionally SproutCore comes with a predefined attribute helper for date and time values.

in apps/app/models/contact.js
App.Contact = SC.Record.extend({ dateOfBirth: SC.Record.attr(SC.DateTime, { format: 'YY-mm-dd' }) });

For a reference of how to specify your custom date format check the documentation of SC.DateTime#toFormattedString.

3.2 - Record Ids

In SproutCore you don't define the primary key property of your models explicitly like you defined your custom attributes above. The records' primary keys are managed by the store, so every record inherently has an ID property. However, you can specify the identifier of this ID property. This is where it can become a bit confusing at first... but let's clear it up step by step.

First of all, by default SproutCore uses the identifier "guid" for the primary key. You can change this identifier by defining a primaryKey property in your model:

in apps/app/models/contact.js
App.Contact = SC.Record.extend({ primaryKey: 'uid' });

If you want to use your custom ID identifier in all your models, you can make your life a bit easier and your code more maintainable by defining a custom record base class, where you define the primaryKey property. Then you can subclass this custom base class to create your models.

However, this primary key identifier is only used to identify the ID property in the underlying data hash, but not to get or set the ID on a record. For example if you create a record and pass a hash with initial values, then SproutCore will now look for a property called "uid" in the hash when you don't explicitly specify an ID. If you want to get or set the ID of a record though, you always use id independent of the primaryKey's value:

myRecord.get('id'); // note: NOT 'uid' myRecord.set('id', 1);

You should never change the ID of an existing record using set() like above unless you know what you are doing.

It is a best practice to never include the ID in the data hash, because then you end up with two IDs: the ID property in the data hash and the ID managed by the store. If you receive a JSON data hash from the server (where the ID is necessarily included) then you should extract and delete the ID from this hash before using it to load the record into the store.

3.3 - Relations

Often models don't exist completely independently of each other but are related to other models. For example one or more addresses could belong to the Contact model we created above. So let's define the Address model first:

apps/app/models/address.js
App.Address = SC.Record.extend({ street: SC.Record.attr(String), number: SC.Record.attr(Number) });
3.3.1 - One-to-One Relations

If we only need one address to be associated with each contact, then we can use the toOne relation helper:

in apps/app/models/contact.js
App.Contact = SC.Record.extend({ address: SC.Record.toOne( 'App.Address', { isMaster: YES, inverse: 'contact' } ) });
in apps/app/models/address.js
App.Address = SC.Record.extend({ contact: SC.Record.toOne( 'App.Contact', { isMaster: NO } ) });

Notice the isMaster and inverse options used with the toOne helper. The isMaster: YES option on the address attribute ensures that the Contact record actually gets marked as changed when you assign a different Address record to it. You should always set the isMaster option to YES on one side of the relation and to NO on the other to control which record is committed back to the server when you alter the relation.

The inverse option specifies the property name of the inverse relation on the associated model and should be set on the side of the relation where isMaster is set to YES.

In the underlying data hash a toOne relation is simply represented as the ID of the associated record.

It is not mandatory to define both directions of the relation if you don't need it.

3.3.2 - One-to-Many Relations

If we want to associate multiple addresses with a certain contact, then we have to use the toMany relation helper:

in apps/app/models/contact.js
App.Contact = SC.Record.extend({ address: SC.Record.toMany( 'App.Address', { isMaster: YES, inverse: 'contact' } ) });
in apps/app/models/address.js
App.Address = SC.Record.extend({ contact: SC.Record.toOne( 'App.Contact', { isMaster: NO } ) });

The only thing that changed compared to the one-to-one example above is the toMany keyword in the Contact model. The isMaster and inverse options apply to toMany relations in the same way as they do to toOne relations.

In the underlying data hash a toMany relation is represented as an array of IDs of the the associated records.

It is not mandatory to define both directions of the relation if you don't need it.

3.3.3 - Many-to-Many Relations

If we not only want to relate multiple addresses to one contact, but also relate one address to multiple contacts, we have to use toMany on both sides of the relation. SproutCore's toMany helper manages many-to-many relations without a join table, which you would use in a relational database:

in apps/app/models/contact.js
App.Contact = SC.Record.extend({ address: SC.Record.toMany( 'App.Address', { isMaster: YES, inverse: 'contact' } ) });
in apps/app/models/address.js
App.Address = SC.Record.extend({ contact: SC.Record.toMany( 'App.Contact', { isMaster: NO } ) });

Again the only thing that changed compared to the one-to-many example from above is the use of the toMany helper in the Address model.

Since a many-to-many relation effectively is constructed by using toMany on both sides, it is represented in the underlying data hashes of both sides of the relation as an array of record IDs.

It is not mandatory to define both directions of the relation if you don't need it.

3.4 - Other Properties on Model Classes

Any property defined on a model class not using SC.Record.attr is a transient property. This means that its value is not passed through to the data hash of the record and therefore is neither committed back to the server nor loaded from incoming JSON data.

in apps/app/models/contact.js
App.Contact = SC.Record.extend({ // transient property isContact: YES, // transient computed property fullName: function() { return this.get('firstName') + ' ' + this.get('lastName'); }.property('firstName', 'lastName').cacheable() });

If you use the set method on an undefined property, SproutCore by default will pass the value through to the underlying data hash. You can turn this behavior off by setting ignoreUnknownProperties: YES in your model classes.

4 - Using Your Models

Now that we have defined our Contact and Address models it's time to actually create some records. All records are managed by the store, so we have to make sure first that we have an instance of SC.Store available. Usually the store is instantiated somewhere in your application's core.js file:

in apps/app/core.js
App = SC.Application.create({ store: SC.Store.create().from(SC.Record.fixtures) });

In this example, we create the store with fixtures as data source. You can read more about fixtures and other data sources in the respective guides.

4.1 - Creating Records

You can create records of a previously defined record type like this:

contact = App.store.createRecord(App.Contact, {});

The first argument of the store's createRecord method is the record type. The second argument is a hash with optional initial values. Furthermore you can specify the record ID as third argument:

contact = App.store.createRecord( App.Contact, { firstName: 'Florian', lastName: 'Kugler' }, 99 );

Usually you will not specify an ID like this, because either you get the record ID from the server, or you want to use some kind of temporary ID on new records until they get committed to the server, which then can return a persistent ID. So let's use a temporary ID:

contact = App.store.createRecord( App.Contact, { firstName: 'Florian', lastName: 'Kugler' }, - Math.random(Math.floor(Math.random() * 99999999)) );

IDs are not limited to numbers, but can also be strings.

When you create a record its status will be READY_NEW, indicating that the record is editable and does not exist on the server yet.

4.1.1 - Creating Associated Records

When creating associated records, you first have to create the records and afterwards establish the connection between the records.

contact = App.store.createRecord(App.Contact, {/*...*/}, 1); address = App.store.createRecord(App.Address, {/*...*/}, 1); // for a toOne relation contact.set('address', address); // for a toMany relation contact.get('address').pushObject(address);

In this case we're adding the Address record to the Contact record, because Contact is defined as master in this relation and has the inverse property set. It is important to add the non-master record to the master record in order to set up the connection between these records properly.

4.2 - Updating Records

Updating record attributes is as easy as calling the set method:

contact.set('firstName', 'Jack');

In order to be able to update record attributes the record has to be in a READY state. If you update an attribute of a newly created record, the status will still be READY_NEW. If you update an attribute of a record that was previously loaded from the server or committed to the server, then the status will transition from READY_CLEAN to READY_DIRTY.

Dirty states always indicate that the record needs to be committed back to the server.

4.3 - Destroying Records

To delete a certain record, just call the destroy method on it:

contact.destroy();

Just as when updating a record, the record has to be in a READY state to be able to be destroyed. If you destroy a newly created record (which was not yet committed to the server) the status will transition from READY_NEW to DESTROYED_CLEAN, indicating that there is no need to tell the server about the destroy, since it never knew about this record in the first place. If you destroy a record loaded from the server, then the state will transition from READY_CLEAN (or READY_DIRTY if you changed it before) to DESTROYED_DIRTY, indicating that the server needs to be notified about this destroy action.

4.4 - Getting Information about Records

You can get the ID, the store key and the status of a record by calling the get method on the respective properties:

id = contact.get('id'); storeKey = contact.get('storeKey'); status = contact.get('status');

To test if the record is currently in a certain state, use JavaScript's binary operators:

status = contact.get('status'); // checks if the record is in any READY state if (status & SC.Record.READY) { } // checks if the record is in the READY_NEW state if (status === SC.Record.READY_NEW) { }

For a complete list of record state constants see the documentation of the SC.Record class.

5 - Finding Records in the Store

Because the store manages all records in memory, you can query it for records of a certain type, records with a certain ID or more complex search criteria.

5.1 - Finding a Specific Record by ID

If you know the type and the ID of the record you want to retrieve, you can just hand these two parameters to the store's find method:

contact = App.store.find(App.Contact, 1);

This statement returns the record of type App.Contact with the ID 1. If the record does not exist, then the return value will be null.

When find is called with a record type and an ID as arguments, it only looks for records of exactly this type. It will not return records which type is a subclass of the specified record type.

5.2 - Finding All Records of a Certain Type

To find all records of one record type, just pass that type to the find method:

contacts = App.store.find(App.Contact);

If you want to find all records of several record types, pass an array of record types to the find method:

contactsAndAddresses = App.store.find( [App.Contact, App.Address] );

You can also find all records of a certain type and all its subclasses:

allRecords = App.store.find(SC.Record);

The above statement returns all records in your application, because we are asking for all records of type SC.Record, which is SproutCore's base model class.

Internally find converts the specified record types to a query. find is just a convenient method to save some characters of typing required to create the query yourself. Read on in the next section how to do this and to learn more about the return type of find.

5.3 - Using Queries

SproutCore features a SQL-like query language to facilitate more complex queries to the store. To demonstrate, let us first translate the find calls of the previous section to using queries, as find does internally.

To build a query which looks for all records of a certain type, you just call SC.Query.local with this record type as argument and pass this query to find:

query = SC.Query.local(App.Contact); contacts = App.store.find(query);

As you can see, the method from the previous section of directly passing the record type to the find method just saves you the call of SC.Query.local. Querying for multiple record types or all records follows the same pattern:

query = SC.Query.local([App.Contact, App.Address]); contactsAndAddresses = App.store.find(query); query = SC.Query.local(SC.Record); allRecords = App.store.find(query);

Whenever you call SC.Store's find method with a query (or using one of the convenient ways from the previous section) it returns a SC.RecordArray. As the name indicates, SC.RecordArray implements SC.Array and therefore you can use it like a normal read-only array. For example:

contacts.firstObject(); // returns first result contacts.objectAt(3); // returns fourth result contacts.lastObject(); // returns last result

Please refer to the documentation of SC.Array to learn more about the array access methods.

If the query was not yet fetched from the server, the store automatically forwards it to the data source to load the data from the server.

Objects in an SC.RecordArray are automatically updated by the store when you add or remove records to or from the store which match the corresponding query.

5.3.1 - Conditions

You can limit the results of a query to match certain conditions:

query = SC.Query.local(App.Contacts, { conditions: 'firstName = "Florian"' }); results = App.store.find(query);

The above query returns all records of type App.Contacts and subclasses of this type where the firstName attribute matches the value "Florian". You can combine several conditions using the logical operators AND, OR and NOT as well as parentheses ( and ) for grouping:

query = SC.Query.local(App.Contacts, { conditions: 'firstName = "Florian" AND lastName = "Kugler"' }); query = SC.Query.local(App.Contacts, { conditions: '(firstName = "Florian" AND lastName = "Kugler") OR age > 30' });

However, you will not want to hard-code the query conditions, but to make use of variables containing the desired values. For this you can use query parameters.

SproutCore handles two different types of query parameters: sequential and named parameters. Let's rephrase the above query using sequential parameters:

query = SC.Query.local(App.Contacts, { conditions: '(firstName = %@ AND lastName = %@) OR age > %@', parameters: ['Florian', 'Kugler', 30] });

The elements of the parameters array will be inserted sequentially at the positions of the %@ placeholders. Now lets do the same with named parameters:

query = SC.Query.local(App.Contacts, { conditions: '(firstName = {first} AND lastName = {last}) ' + 'OR age > {age}', parameters: { first: 'Florian', last: 'Kugler', age: 30 } });

Which of these methods you use is mainly a matter of personal preference and the complexity of your query.

The arguments inside the query conditions can be of the following types:

  • Attribute names of the record type queried for.
  • null and undefined.
  • true and false.
  • Integer and floating point numbers.
  • Strings (single or double quoted).

Furthermore you can use the following comparison operators:

  • =, !=, <, <=, >=.
  • BEGINS_WITH (checks if a string starts with another one).
  • ENDS_WITH (checks if a string ends with another one).
  • CONTAINS (checks if a string contains another one, or if an object is in an array).
  • MATCHES (checks if a string is matched by a regexp, you will have to use a parameter to insert the regexp).
  • ANY (checks if the thing on its left is contained in the array on its right, you will have to use a parameter to insert the array).
  • TYPE_IS (unary operator expecting a string containing the name of a model class on its right side, only records of this type will match).
5.3.2 - Sorting

To obtain ordered query results you can simply add the orderBy option to your query:

query = SC.Query.local(App.Contacts, { conditions: 'age > 30', orderBy: 'lastName, firstName ASC' });

In this case the results are sorted in an ascending order, first by last name and second by first name. If you omit the ASC keyword, the results are by default sorted in an ascending order. To sort them in descending order, put the keyword DESC after the name of the property.

If you need a custom sorting order, you can register your own comparison operator for a specific model attribute using SC.Query.registerComparison. Please refer to the documentation for further details.

5.3.3 - Scoped Queries

All the queries you used until now will cause the store to match all records in memory with the query's conditions. You can also build one query on top of another to construct more efficient query trees:

query1 = SC.Query.local(App.Contacts, { conditions: 'age > 30', }); aboveThirty = App.store.find(query1); query2 = SC.Query.local(App.Contacts, { conditions: 'lastName BEGINS_WITH "K"' }) results = aboveThirty.find(query2);

The second query is based on the first one by calling find on the RecordArray of the first query instead of App.store. The second query matches the results of the first query against its own conditions. In this case it would return all Contact records where age is greater than 30 and the last name starts with the letter "K".

Scope queries can be thought as chained queries using the AND logical operator.

5.3.4 - Local vs. Remote Queries

You will have noticed the keyword local in the SC.Query.local call we used until now to create the queries. Actually the keyword local is somewhat confusing, because local queries do not act exclusively on the in-memory store but also call the data source to fetch records from the server. The main characteristic of local queries is that the store automatically updates their results whenever the contents of the local in-memory store change.

Remote queries (build with SC.Query.remote), on the other hand, return a SC.RecordArray which is not updated automatically. "Remote" doesn't mean necessarily that the results have to be fetched from a remote server. They could also be loaded from a local browser storage. It's admittedly a bad choice of names.

You should use local queries in almost all cases unless you know what you're doing.

5.4 - Extending SproutCore's Query Language

If SproutCore's built-in query operators are not sufficient for your use case, you can easily extend the query language. For example, by default there are no bit-wise operators, so let's implement a BITAND operator which evaluates to true if the bit-wise and of the two arguments is unequal to zero:

SC.Query.registerQueryExtension('BITAND', { reservedWord: true, leftType: 'PRIMITIVE', rightType: 'PRIMITIVE', evalType: 'BOOLEAN', evaluate: function (r,w) { var left = this.leftSide.evaluate(r,w); var right = this.rightSide.evaluate(r,w); return (left & right) !== 0; } });

We call SC.Query.registerQueryExtension to register the new operator with the name BITAND as first argument. The key components of the hash passed as second argument are evalType and evaluate. evalType is either BOOLEAN (if you return a boolean value in evaluate) or PRIMITIVE (if you return e.g. a number or a string). The actual operation is implemented in the evaluate function after the operands are retrieved by this.leftSide.evaluate(r,w) and this.rightSide.evaluate(r,w).

Look at the source of SC.Query for more examples of how to implement query operators.

6 - Changelog