realm-js/README.md

# RealmJS
Realm is a mobile database that runs directly inside phones, tablets or wearables. This repository holds the source code for Realm's JavaScript bindings for integrating with mobile apps built using ReactNative and Apache Cordova (PhoneGap).

## Setup
This repository uses submodules so you need to run `git submodule update --init --recursive` in the realm-js root directory before running any examples or including the project in your app.

## ReactNative Example
Make sure your environment is set up to run react native applications. Follow the instructions here https://facebook.github.io/react-native/docs/getting-started.html.

The ReactNative example project is in the `examples/ReactExample` directory. You need to run `npm install` in this directory before running the example for the first time.

## ReactNative Project Setup
- Create a new ReactNative project `react-native init <project-name>` and open the generated XCode project.
- Drag `RealmJS.xcodeproj` into the `Libraries` folder in your project.
- Drag `RealmReact.framework` from the `Products` directory under `RealmJS.xcodeproj` into the `Embedded Binaries` section in the `General` tab for your app's target settings. This bundles the library with your app.
- In the `Build Phases` tab for your app's target settings, add `RealmReact.framework` in the `Target Dependencies` and `Link Binary with Library` build phases.
- In your app's `package.json` file, add the `realm` dependency with a path to the `realm-js/lib` folder like this: `"realm": "file:path/to/realm-js/lib"` (symlinks are not yet supported by the React Native packager, see [issue #637](https://github.com/facebook/react-native/issues/637)).
- You can now `require('realm')` in your app's JS to use Realm!

## Getting Started
Start with creating a `realm` by passing it an array of `objectSchema` (object types and their properties) for each type of object it will contain:

```js
const Realm = require('realm');

const personSchema = {
    name: 'Person',
    primaryKey: 'name',
    properties: [
        {name: 'name', type: Realm.Types.STRING},
        {name: 'birthday', type: Realm.Types.DATE},
        {name: 'friends', type: Realm.Types.LIST, objectType: 'Person'},
        {name: 'points', type: Realm.Types.INT, default: 0},
    ],
};

const realm = new Realm({schema: [personSchema]});
```

If you'd prefer your objects inherit from a prototype, you just need to define the `schema` on the `prototype` object and instead pass in the constructor when creating a `realm`:

```js
function Person() {}
Person.prototype = {
    schema: personSchema,
    get age() {
        return Math.floor((Date.now() - this.birthday.getTime()) / 31557600000);
    },
};

const realm = new Realm({schema: [Person]});
```

You can now use the `realm` instance to create new objects. When using Realm, all mutations must take place inside of a write transaction:

```js
realm.write(() => {
    ross = realm.create('Person', {
        name: 'Ross Geller',
        birthday: new Date(1967, 9, 18),
        friends: [chandler, joey, monica, phoebe, rachel],
    });
});
```

When creating an object, values for all properties without default values need to be specified. In the example above, since the `points` property has a default property it can be omitted.

Changes to object properties and object deletions also need to take place in a write transactions:

```js
realm.write(() => {
    rachel.points++;
    rachel.friends.push(ross);
    realm.delete(janine);
});
```

**Note:** If an uncaught exception occurs during a write transaction, then the write transaction will rollback and all object creations, deletions and modifications will be undone.

You can query for existing objects by passing the object type and an optional query into the `realm.objects()` method:

```js
let characters = realm.objects('Person');
let chandler = realm.objects('Person', 'name = "Chandler Bing"')[0];
```

Queries are live updating, so as change are made to a Realm queries are updated automatically to reflect those changes.

You can see more examples of how to use these APIs in the [ReactExample](https://github.com/realm/realm-js/tree/master/examples/ReactExample) app and in the [JS test files](https://github.com/realm/realm-js/tree/master/tests).

## Documentation
### `Realm` Constructor Options
#### `new Realm(realmConfig)`
The `realmConfig` passed to the constructor can contain the following:

- `schema` – required when first accessing a realm - array of `ObjectSchema` or object constructors (see below)
- `path` – optional - defaults to `Realm.defaultPath` (which initially is `'Documents/default.realm'`)
- `schemaVersion` – optional - defaults to `0` but must be specified and incremented after changing the schema

### ObjectSchema
- `name` – string used to refer to this object type
- `properties` - array of property defitions (see below)
- `primaryKey` – optional - name of `STRING` or `INT` property that should be unique

### Property Types
When definining object `properties` in a `schema`, each should have a unique `name`, and the `type` of each property must be defined as either the name of an object type in the same schema **or** as one of the following:

- `Realm.Types.BOOL`
- `Realm.Types.INT`
- `Realm.Types.FLOAT`
- `Realm.Types.DOUBLE`
- `Realm.Types.STRING`
- `Realm.Types.DATE`
- `Realm.Types.DATA`
- `Realm.Types.OBJECT` (requires `objectType`, is always `optional`)
- `Realm.Types.LIST` (requires `objectType`, is never `optional`)

You _may_ specify these property options as well:

- `default` – default value when property was not specified on creation
- `optional` – boolean indicating if this property may be assigned `null` or `undefined`

### `Realm` Instance Methods
#### `create(type, props [, update])`
- `type` – string matching object `name` in the `schema` definition
- `props` – object with property values for all required properties without a default value
- `update` – optional – boolean signaling that an existing object (matching primary key) should be updated – only the primary key property and properties which should be updated need to be specified for the `props` arguments (all missing property values will remain unchanged)
- _Returns a new realm object instance_

#### `delete(object)`
- `object` – realm object or array of realm objects (which can be a `List` or `Results` object)

#### `deleteAll()`
**WARNING:** This does what you think it does!

#### `objects(type [, query])`
- `type` - string matching object `name` in the `schema` definition
- `query` – optional – string that defines a query to filter results (see tests for examples)
- _Returns `Results` object_

#### `write(callback)`
- `callback` – function that is synchronously called inside the write transaction

#### `addListener(event, callback)`
- `event` – string specifying the event name (only `'change'` is currently supported)
- `callback` – function that is called when that event occurs

#### `removeListener(event, callback)`
- `event` – string specifying the event name (only `'change'` is currently supported)
- `callback` – function that was previously added a listener callback

#### `removeAllListeners([event])`
- `event` – optional – string specifying the event name (only `'change'` is currently supported)

#### `close()`
**WARNING:** This is only for advanced use cases and generally doesn't need to be used.

## License
Copyright 2015 Realm Inc - All Rights Reserved
Proprietary and Confidential