LoopBack models can manipulate data via the DataSource object. Attaching a DataSource to a Model adds instance methods and static methods to the Model.

Define a data source to persist model data. To create a DataSource programmatically, call createDataSource() on the LoopBack object; for example:

var oracle = loopback.createDataSource({
  connector: 'oracle',
  host: '111.22.333.44',
  database: 'MYDB',
  username: 'username',
  password: 'password'
});

All classes in single dataSource share same the connector type and one database connection.

For example, the following creates a DataSource, and waits for a connection callback.

var dataSource = new DataSource('mysql', { database: 'myapp_test' });
dataSource.define(...);
dataSource.on('connected', function () {
    // work with database
});

Define readonly property on object

Define a hidden property

Attach an existing model to a data source.

Drop each model table and re-create. This method applies only to database connectors. For MongoDB, it drops and creates indexes.

WARNING: Calling this function deletes all data! Use autoupdate() to preserve data.

Update existing database tables. This method applies only to database connectors.

Introspect a JSON object and build a model class

Return column metadata for specified modelName and propertyName

Return column name for specified modelName and propertyName

Return column names for specified modelName

Define a model class. Returns newly created model object. The first (String) argument specifying the model name is required. You can provide one or two JSON object arguments, to provide configuration options. See Model definition reference for details.

Simple example:

var User = dataSource.createModel('User', {
    email: String,
    password: String,
    birthDate: Date,
    activated: Boolean
});

More advanced example

var User = dataSource.createModel('User', {
    email: { type: String, limit: 150, index: true },
    password: { type: String, limit: 50 },
    birthDate: Date,
    registrationDate: {type: Date, default: function () { return new Date }},
    activated: { type: Boolean, default: false }
});

You can also define an ACL when you create a new data source with the DataSource.create() method. For example:

var Customer = ds.createModel('Customer', {
      name: {
        type: String,
        acls: [
          {principalType: ACL.USER, principalId: 'u001', accessType: ACL.WRITE, permission: ACL.DENY},
          {principalType: ACL.USER, principalId: 'u001', accessType: ACL.ALL, permission: ACL.ALLOW}
        ]
      }
    }, {
      acls: [
        {principalType: ACL.USER, principalId: 'u001', accessType: ACL.ALL, permission: ACL.ALLOW}
      ]
    });

Define foreign key to another model

Define an operation to the data source

Define single property named prop on model

Disable remote access to a data source operation. Each connector has its own set of set enabled and disabled operations. To list the operations, call dataSource.operations().

var oracle = loopback.createDataSource({
  connector: require('loopback-connector-oracle'),
  host: '...',
  ...
});
oracle.disableRemote('destroyAll');

Notes:

• Disabled operations will not be added to attached models.
• Disabling the remoting for a method only affects client access (it will still be available from server models).
• Data sources must enable / disable operations before attaching or creating models.

Close database connection

Discover and build models from the specified owner/modelName.

Discover and build models from the given owner/modelName synchronously.

Retrieves a description of the foreign key columns that reference the given table's primary key columns (the foreign keys exported by a table), ordered by fkTableOwner, fkTableName, and keySeq.

Callback function return value is an object that can have the following properties:

The synchronous version of discoverExportedForeignKeys

Discover foreign keys for a given owner/modelName

Callback function return value is an object that can have the following properties:

The synchronous version of discoverForeignKeys

Discover existing database tables. This method returns an array of model objects, including {type, name, onwer}

The synchronous version of discoverModelDefinitions.

Discover properties for a given model.

Callback function return value is an object that can have the following properties:

The synchronous version of discoverModelProperties

Discover primary keys for a given owner/modelName. Callback function return value is an object that can have the following properties:

The synchronous version of discoverPrimaryKeys

Discover one schema from the given model without following the relations. Example schema from oracle connector:*

    {
      "name": "Product",
      "options": {
        "idInjection": false,
        "oracle": {
          "schema": "BLACKPOOL",
          "table": "PRODUCT"
        }
      },
      "properties": {
        "id": {
          "type": "String",
          "required": true,
          "length": 20,
          "id": 1,
          "oracle": {
            "columnName": "ID",
            "dataType": "VARCHAR2",
            "dataLength": 20,
            "nullable": "N"
          }
        },
        "name": {
          "type": "String",
          "required": false,
          "length": 64,
          "oracle": {
            "columnName": "NAME",
            "dataType": "VARCHAR2",
            "dataLength": 64,
            "nullable": "Y"
          }
        },
...
        "fireModes": {
          "type": "String",
          "required": false,
          "length": 64,
          "oracle": {
            "columnName": "FIRE_MODES",
            "dataType": "VARCHAR2",
            "dataLength": 64,
            "nullable": "Y"
          }
        }
      }
    }

Discover schema from a given modelName/view.

Discover schema from a given table/view synchronously

Enable remote access to a data source operation. Each connector has its own set of set remotely enabled and disabled operations. To list the operations, call dataSource.operations().

Freeze dataSource. Behavior depends on connector

See ModelBuilder.getModel

See ModelBuilder.getModelDefinition

Get an operation's metadata.

Get the data source types

Find the ID column name

Find the ID property name

Find the ID property names sorted by the index

Find the id property definition

Check whether migrations needed This method applies only to SQL connectors.

Check if the backend is a relational DB

Return JSON object describing all operations.

Example return value:

{
 find: {
   remoteEnabled: true,
   accepts: [...],
   returns: [...]
   enabled: true
},
 save: {
   remoteEnabled: true,
   prototype: true,
   accepts: [...],
   returns: [...],
   enabled: true
 },
 ...
}

Ping the underlying connector to test the connections

Check the data source supports the specified types.

Return table name for specified modelName

Model class: base class for all persistent objects.

ModelBaseClass mixes Validatable and Hookable classes methods

Define a property on the model.

Return string representation of class This overrides the default toString() method

Reset dirty attributes. This method does not perform any database operations; it just resets the object to its initial state.

Convert model instance to a plain JSON object. Returns a canonical object representation (no getters and setters).

The GeoPoint object represents a physical location.

For example:

var loopback = require(‘loopback’);
var here = new loopback.GeoPoint({lat: 10.32424, lng: 5.84978});

Embed a latitude / longitude point in a model.

var CoffeeShop = loopback.createModel('coffee-shop', {
  location: 'GeoPoint'
});

You can query LoopBack models with a GeoPoint property and an attached data source using geo-spatial filters and sorting. For example, the following code finds the three nearest coffee shops.

CoffeeShop.attachTo(oracle);
var here = new GeoPoint({lat: 10.32424, lng: 5.84978});
CoffeeShop.find( {where: {location: {near: here}}, limit:3}, function(err, nearbyShops) {
  console.info(nearbyShops); // [CoffeeShop, ...]
});

Determine the spherical distance between two GeoPoints.

Determine the spherical distance to the given point. Example:

var loopback = require(‘loopback’);

var here = new loopback.GeoPoint({lat: 10, lng: 10});
var there = new loopback.GeoPoint({lat: 5, lng: 5});

loopback.GeoPoint.distanceBetween(here, there, {type: 'miles'}) // 438

Simple serialization.

Hooks object.

Find the idKey of a Model.

Utility Function to allow interleave before and after high computation tasks

Inclusion - Model mixin.

call relation specific include functions

Enables you to load relations of several objects and optimize numbers of requests.

Examples:

Load all users' posts with only one additional request: User.include(users, 'posts', function() {}); Or User.include(users, ['posts'], function() {});

Load all users posts and passports with two additional requests: User.include(users, ['posts', 'passports'], function() {});

Load all passports owner (users), and all posts of each owner loaded: Passport.include(passports, {owner: 'posts'}, function() {}); Passport.include(passports, {owner: ['posts', 'passports']}); ``` Passport.include(passports, {owner: [{posts: 'images'}, 'passports']});

Handle Inclusion of EmbedsMany/EmbedsManyWithBelongsTo/EmbedsOne Relations. Since Embedded docs are part of parents, no need to make db calls. Let the related function be called for each object to fetch the results from cache.

TODO: Optimize EmbedsManyWithBelongsTo relation DB Calls

Handle inclusion of HasMany relation

Handle inclusion of HasManyThrough/HasAndBelongsToMany/Polymorphic HasManyThrough relations

Handle Inclusion of BelongsTo/HasOne relation

Handle Inclusion of Polymorphic BelongsTo relation

Handle Inclusion of Polymorphic HasOne relation

Handle inclusion of ReferencesMany relation

Process Polymorphic objects of each type (modelType)

Process Each Model Object and make sure specified relations are included

Sets the related objects as a property of Parent Object

Process fetched related objects

Process fetched related objects

Process fetched related objects

Handle the fetched target objects

Process fetched related objects

Handle the results of Through model objects and fetch the modelTo items

ModelBuilder - A builder to define data models.

Extend the model with the specified model, properties, and other settings. For example, to extend an existing model, for example, a built-in model:

var Customer = User.extend('customer', {
  accountId: String,
  vip: Boolean
});

To extend the base model, essentially creating a new model:

var user = loopback.Model.extend('user', properties, options);

Register a property for the model class

Introspect the JSON document to build a corresponding model.

Build models from schema definitions

schemas can be one of the following:

1. An array of named schema definition JSON objects
2. A schema definition JSON object
3. A list of property definitions (anonymous)

Define a model class. Simple example:

var User = modelBuilder.define('User', {
    email: String,
    password: String,
    birthDate: Date,
    activated: Boolean
});

More advanced example:

var User = modelBuilder.define('User', {
    email: { type: String, limit: 150, index: true },
    password: { type: String, limit: 50 },
    birthDate: Date,
    registrationDate: {type: Date, default: function () { return new Date }},
    activated: { type: Boolean, default: false }
});

Define single property named propertyName on model

Define a new value type that can be used in model schemas as a property type.

Extend existing model with specified properties

Example: Instead of extending a model with attributes like this (for example):

    db.defineProperty('Content', 'competitionType',
      { type: String });
    db.defineProperty('Content', 'expiryDate',
      { type: Date, index: true });
    db.defineProperty('Content', 'isExpired',
      { type: Boolean, index: true });

This method enables you to extend a model as follows (for example):

    db.extendModel('Content', {
      competitionType: String,
      expiryDate: { type: Date, index: true },
      isExpired: { type: Boolean, index: true }
    });

Get a model by name.

Get the model definition by name

Get the schema name

Resolve the type string to be a function, for example, 'String' to String. Returns {Function} if the type is resolved

RelationMixin class. Use to define relationships between models.

Declare "belongsTo" relation that sets up a one-to-one connection with another model, such that each instance of the declaring model "belongs to" one instance of the other model.

For example, if an application includes users and posts, and each post can be written by exactly one user. The following code specifies that Post has a reference called author to the User model via the userId property of Post as the foreign key.

Post.belongsTo(User, {as: 'author', foreignKey: 'userId'});

You can then access the author in one of the following styles. Get the User object for the post author asynchronously:

post.author(callback);

Get the User object for the post author synchronously:

post.author();
Set the author to be the given user:

post.author(user)

Examples:

Suppose the model Post has a *belongsTo* relationship with User (the author of the post). You could declare it this way:
```js
Post.belongsTo(User, {as: 'author', foreignKey: 'userId'});

When a post is loaded, you can load the related author with:

post.author(function(err, user) {
    // the user variable is your user object
});

The related object is cached, so if later you try to get again the author, no additional request will be made. But there is an optional boolean parameter in first position that set whether or not you want to reload the cache:

post.author(true, function(err, user) {
    // The user is reloaded, even if it was already cached.
});

This optional parameter default value is false, so the related object will be loaded from cache if available.

A hasAndBelongsToMany relation creates a direct many-to-many connection with another model, with no intervening model. For example, if your application includes users and groups, with each group having many users and each user appearing in many groups, you could declare the models this way:

 User.hasAndBelongsToMany('groups', {model: Group, foreignKey: 'groupId'});

Then, to get the groups to which the user belongs:

 user.groups(callback);

Create a new group and connect it with the user:

 user.groups.create(data, callback);

Connect an existing group with the user:

 user.groups.add(group, callback);

Remove the user from the group:

 user.groups.remove(group, callback); 

Define a "one to many" relationship by specifying the model name

Examples:

User.hasMany(Post, {as: 'posts', foreignKey: 'authorId'});

Book.hasMany(Chapter);

Or, equivalently:

Book.hasMany('chapters', {model: Chapter});

Query and create related models:

Book.create(function(err, book) {

  // Create a chapter instance ready to be saved in the data source.
  var chapter = book.chapters.build({name: 'Chapter 1'});

  // Save the new chapter
  chapter.save();

 // you can also call the Chapter.create method with the `chapters` property which will build a chapter
 // instance and save the it in the data source.
 book.chapters.create({name: 'Chapter 2'}, function(err, savedChapter) {
 // this callback is optional
 });

  // Query chapters for the book  
  book.chapters(function(err, chapters) {  // all chapters with bookId = book.id 
    console.log(chapters);
  });

  book.chapters({where: {name: 'test'}, function(err, chapters) {
   // All chapters with bookId = book.id and name = 'test'
    console.log(chapters);
  });
});

ObserverMixin class. Use to add observe/notifyObserversOf APIs to other classes.

Unregister all asynchronous observers for the given operation (event).

Run the given function with before/after observers. It's done in three serial steps asynchronously:

• Notify the registered observers under 'before ' + operation
• Execute the function
• Notify the registered observers under 'after ' + operation

If an error happens, it fails fast and calls the callback with err.

Invoke all async observers for the given operation(s).

Register an asynchronous observer for the given operation (event).

Unregister an asynchronous observer for the given operation (event).

TransactionMixin class. Use to add transaction APIs to a model class.

Begin a new transaction

Commit a transaction and release it back to the pool

Rollback a transaction and release it back to the pool

This class provides methods that add validation cababilities to models. Each of the validations runs when the obj.isValid() method is called.

All of the methods have an options object parameter that has a message property. When there is only a single error message, this property is just a string; for example: Post.validatesPresenceOf('title', { message: 'can not be blank' });

In more complicated cases it can be a set of messages, for each possible error condition; for example: User.validatesLengthOf('password', { min: 6, max: 20, message: {min: 'too short', max: 'too long'}});

Validate using custom validation function.

Example:

User.validate('name', customValidator, {message: 'Bad name'});
function customValidator(err) {
    if (this.name === 'bad') err();
});
var user = new User({name: 'Peter'});
user.isValid(); // true
user.name = 'bad';
user.isValid(); // false

Validate using custom asynchronous validation function.

Example:

    User.validateAsync('name', customValidator, {message: 'Bad name'});
    function customValidator(err, done) {
        process.nextTick(function () {
            if (this.name === 'bad') err();
            done();
        });
    });
    var user = new User({name: 'Peter'});
    user.isValid(); // false (because async validation setup)
    user.isValid(function (isValid) {
        isValid; // true
    })
    user.name = 'bad';
    user.isValid(); // false
    user.isValid(function (isValid) {
        isValid; // false
    })

Validate absence of one or more specified properties. A model should not include a property to be considered valid; fails when validated field not blank.

For example, validate absence of reserved ``` Post.validatesAbsenceOf('reserved', { unless: 'special' });

Validate exclusion. Require a property value not be in the specified array.

Example: Company.validatesExclusionOf('domain', {in: ['www', 'admin']});

Validate format. Require a model to include a property that matches the given format.

Require a model to include a property that matches the given format. Example: User.validatesFormat('name', {with: /\w+/});

Validate inclusion in set. Require a value for property to be in the specified array.

Example:

User.validatesInclusionOf('gender', {in: ['male', 'female']});
User.validatesInclusionOf('role', {
    in: ['admin', 'moderator', 'user'], message: 'is not allowed'
});

Validate length. Require a property length to be within a specified range. Three kinds of validations: min, max, is.

Default error messages:

• min: too short
• max: too long
• is: length is wrong

Example: length validations

User.validatesLengthOf('password', {min: 7});
User.validatesLengthOf('email', {max: 100});
User.validatesLengthOf('state', {is: 2});
User.validatesLengthOf('nick', {min: 3, max: 15});

Example: length validations with custom error messages

User.validatesLengthOf('password', {min: 7, message: {min: 'too weak'}});
User.validatesLengthOf('state', {is: 2, message: {is: 'is not valid state name'}});

Validate numericality. Requires a value for property to be either an integer or number.

Example

User.validatesNumericalityOf('age', { message: { number: '...' }});
User.validatesNumericalityOf('age', {int: true, message: { int: '...' }});

Validate presence of one or more specified properties. Requires a model to include a property to be considered valid; fails when validated field is blank.

For example, validate presence of title

Post.validatesPresenceOf('title');

Validate that model has first, last, and age properties:

User.validatesPresenceOf('first', 'last', 'age');

Example with custom message

Post.validatesPresenceOf('title', {message: 'Cannot be blank'});

Validate uniqueness. Ensure the value for property is unique in the collection of models. Not available for all connectors. Currently supported with these connectors:

• In Memory
• Oracle
• MongoDB

// The login must be unique across all User instances.
User.validatesUniquenessOf('login');

// Assuming SiteUser.belongsTo(Site)
// The login must be unique within each Site.
SiteUser.validateUniquenessOf('login', { scopedTo: ['siteId'] });

ValidationError is raised when the application attempts to save an invalid model instance. Example:

{
  "name": "ValidationError",
  "status": 422,
  "message": "The Model instance is not valid. \
 See `details` property of the error object for more info.",
  "statusCode": 422,
  "details": {
    "context": "user",
   "codes": {
     "password": [
        "presence"
      ],
      "email": [
        "uniqueness"
      ]
   },
    "messages": {
      "password": [
       "can't be blank"
     ],
      "email": [
        "Email already exists"
      ]
    }
  },
}

You might run into situations where you need to raise a validation error yourself, for example in a "before" hook or a custom model method.

MyModel.prototype.preflight = function(changes, callback) {
  // Update properties, do not save to db
  for (var key in changes) {
    model[key] = changes[key];
  }

  if (model.isValid()) {
    return callback(null, { success: true });
  }

  // This line shows how to create a ValidationError
  err = new ValidationError(model);
  callback(err);
}

This method performs validation and triggers validation hooks. Before validation the obj.errors collection is cleaned. Each validation can add errors to obj.errors collection. If collection is not blank, validation failed.

NOTE: This method can be called as synchronous only when no asynchronous validation is configured. It's strongly recommended to run all validations as asyncronous.

Example: ExpressJS controller: render user if valid, show flash otherwise

user.isValid(function (valid) {
    if (valid) res.render({user: user});
    else res.flash('error', 'User is not valid'), console.log(user.errors), res.redirect('/users');
});

Another example:

user.isValid(function (valid) {
    if (!valid) {
          console.log(user.errors);
        // => hash of errors
        // => {
        // => username: [errmessage, errmessage, ...],
        // => email: ...
        // => }
    }
});