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Datastore-agnostic ORM in JavaScript

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Model

Build Status

Model is a datastore-agnostic ORM in JavaScript. It serves as the model-component for the Geddy MVC Web framework for NodeJS.

TOC

Overview

Model currently implements adapters for:

  • Postgres
  • MySQL
  • SQLite
  • Riak
  • MongoDB
  • LevelDB
  • In-memory
  • Filesystem

License

Apache License, Version 2

Prerequisites

Model requires version 0.8.x of Node.js or higher. If you want to run the tests, or work on Model, you'll want the Jake JavaScript build-tool.

Installing with NPM

npm install model

Hacking on Model: running tests

Run the tests with jake test. Run only unit tests with jake test[unit].

The integration tests require the appropriate database and supporting library. (For example, running the Postgres tests require a running Postgres server, and the 'pg' module NPM-installed in your model project directory.) To install the needed modules, just run npm install in the root model directory.

To run the tests on a specific adapter, use jake test[mongo], jake test[postgres], or jake test[memory].

Configure adapter options by creating a test/db.json file. See test/db.sample.json for available options.

Bootstrapping Model

Model serves as the model component inside the Geddy Web framework (http://geddyjs.org/). But it can easily be used as an ORM on its own. Here's a minimal example which uses the LevelDB adapter for the defined model:

var model = require('model')
  , Zerb;

Zerb = function () {
  this.property('title', 'string');
  this.setAdapter('level', {
    db: './data'
  });
};

model.registerDefinitions([{
  ctorName: 'Zerb'
, ctor: Zerb
}]);

var z = model.Zerb.create({title: 'asdf'});

z.save(function (err, data) {
  if (err) { throw err; }
  console.log('Zerb ' + z.title + ' saved.');
});

Pass the string name of the desired adapter (e.g., 'level', 'postgres') followed any config options to the setAdapter method when defining your model.

Defining models

Model uses a pretty simple syntax for defining a model. (It should look familiar to anyone who has used an ORM like ActiveRecord, DataMapper, Django's models, or SQLAlchemy.)

var User = function () {
  this.property('login', 'string', {required: true});
  this.property('password', 'string', {required: true});
  this.property('lastName', 'string');
  this.property('firstName', 'string');

  this.validatesPresent('login');
  this.validatesFormat('login', /[a-z]+/, {message: 'Subdivisions!'});
  this.validatesLength('login', {min: 3});
  this.validatesConfirmed('password', 'confirmPassword');
  this.validatesWithFunction('password', function (s) {
      // Something that returns true or false
      return s.length > 0;
  });

  // Can define methods for instances like this
  this.someMethod = function () {
    // Do some stuff
  };
};

// Can also define them on the prototype
User.prototype.someOtherMethod = function () {
  // Do some other stuff
};

User = model.register('User', User);

Abbreviated syntax

Alternatively, you can use the defineProperties method to lay out your model's properties in one go:

var User = function () {
  this.defineProperties({
    login: {type: 'string', required: true}
  , password: {type: 'string', required: true}
  , lastName: {type: 'string'}
  , firstName: {type: 'string'}
  });
}

Adapters

You can specify a different adapter for each model or apply the same adapter to all models.

var adapter = model.createAdapter('postgres', {
  host: 'localhost',
  username: 'user',
  password: 'password',
  database: 'mydb'
});

model.User.adapter = adapter;
model.Zerb.adapter = adapter;

You can also define a defaultAdapter which will be used by default. Then you can override it on individual models.

model.defaultAdapter = model.createAdapter('memory');

var postgresAdapter = model.createAdapter('postgres', {
  host: 'localhost',
  username: 'user',
  password: 'password',
  database: 'mydb'
});

// User model gets the defaultAdapter
model.Zerb.adapter = postgresAdapter;

Datatypes

Model supports the following datatypes:

  • string
  • text
  • number
  • int
  • boolean
  • date
  • datetime
  • time
  • object

Creating instances

Creating an instance of one of these models is easy:

var params = {
  login: 'alex'
, password: 'lerxst'
, lastName: 'Lifeson'
, firstName: 'Alex'
};
var user = User.create(params);

Validations

Validations provide a nice API for making sure your data items are in a good state. When an item is "valid," it means that its data meet all the criteria you've set for it. You can specify that certain fields have to be present, have to be certain length, or meet any other specific criteria you want to set.

Here's a list of supported validation methods:

  • validatesPresent -- ensures the property exists
  • validatesAbsent -- ensures the property does not exist
  • validatesLength -- ensures the minimum, maximum, or exact length
  • validatesFormat -- validates using a passed-in regex
  • validatesConfirmed -- validates a match against another named parameter
  • validatesWithFunction -- uses an arbitrary function to validate

Common options

You can specify a custom error message for when a validation fails using the 'message' option:

var Zerb = function () {
  this.property('name', 'string');
  this.validatesLength('name', {is: 3, message: 'Try again, gotta be 3!'});
};

You can decide when you want validations to run by passing the 'on' option.

var User = function () {
  this.property('name', 'string', {required: false});
  this.property('password', 'string', {required: false});

  this.validatesLength('name', {min: 3, on: ['create', 'update']});
  this.validatesPresent('password', {on: 'create'});
  this.validatesConfirmed('password', 'confirmPassword', {on: 'create'});
};

// Name validation will pass, but password will fail
myUser = User.create({name: 'aaa'});

The default behavior is for validation on both 'create' and 'update':

  • create - validates on .create
  • update - validates on .updateProperties

You can also define custom validation scenarios other than create and update. (There is a builtin custom 'reify' scenario which is uses when instantiating items out of your datastore. This happens on the first and all query methods.)

// Force validation with the `reify` scenario, ignore the too-short name property
myUser = User.create({name: 'aa'}, {scenario: 'reify'});

// You can also specify a scenario with these methods:
// Enforce 'create' validations on a fetch -- may result in invalid instances
User.first(query, {scenario: 'create'}, cb);
// Do some special validations you need for credit-card payment
User.updateProperties(newAttrs, {scenario: 'creditCardPayment'});

Validation errors

Any validation errors show up inside an errors property on the instance, keyed by field name. Instances have an isValid method that returns a Boolean indicating whether the instance is valid.

// Leaving out the required password field
var params = {
  login: 'alex'
};
var user = User.create(params);

// Prints 'false'
console.log(user.isValid());
// Prints 'Field "password" is required'
console.log(user.errors.password);

Saving items

After creating the instance, call the save method on the instance. This method takes a callback in the familiar (err, data) format for Node.

if (user.isValid()) {
  user.save(function (err, data) {
    if (err) {
      throw err;
    }
    console.log('New item saved!');
  });
}

Updating items

Use the updateProperties method to update the values of the properties on an instance with the appropriate validations. Then call save on the instance.

user.updateProperties({
  login: 'alerxst'
});
if (user.isValid()) {
  user.save(function (err, data) {
    if (err) {
      throw err;
    }
    console.log('Item updated!');
  });
}

Removing items

Use the remove method to remove one ore multiple instances.

model.User.remove(user.id, function(err) {
  if (err) {
    throw err;
  }
  console.log('Item removed!');
});

You can also pass a query to the remove method instead of an id.

Lifecycle events

Both the base model 'constructors,' and model instances are EventEmitters. They emit events during the create/update/remove lifecycle of model instances. In all cases, the plain-named event is fired after the event in question, the 'before'-prefixed event, of course happens before.

The 'constructor' for a model emits the following events:

  • beforeCreate
  • create
  • beforeValidate
  • validate
  • beforeUpdateProperties
  • updateProperties
  • beforeSave (new instances, single and bulk)
  • save (new instances, single and bulk)
  • beforeUpdate (existing single instances, bulk updates)
  • update (existing single instances, bulk updates)
  • beforeRemove
  • remove

Model-item instances emit these events:

  • beforeUpdateProperties
  • updateProperties
  • beforeSave
  • save
  • beforeUpdate
  • update

Model-item instances also have the following lifecycle methods:

  • afterCreate
  • beforeValidate
  • afterValidate
  • beforeUpdateProperties
  • afterUpdateProperties
  • beforeSave
  • afterSave
  • beforeUpdate
  • afterUpdate

If these methods are defined, they will be called at the appropriate time:

var User = function () {
  this.property('name', 'string', {required: false});

  // Lowercase the name before validating
  this.beforeValidate = function () {
    // `this` will refer to the model instance
    this.name = this.name.toLowerCase();
  };
};

Associations

Model has support for associations: including hasMany/belongsTo and hasOne/belongsTo. For example, if you had a User model with a single Profile, and potentially many Accounts:

var User = function () {
  this.property('login', 'string', {required: true});
  this.property('password', 'string', {required: true});
  this.property('confirmPassword', 'string', {required: true});

  this.hasOne('Profile');
  this.hasMany('Accounts');
};

A Book model that belongs to an Author would look like this:

var Book = function () {
  this.property('title', 'string');
  this.property('description', 'text');

  this.belongsTo('Author');
};

Creating associations

Add the hasOne relationship by calling 'set' plus the name of the owned model in singular (in this case setProfile). Retrieve the associated item by using 'get' plus the name of the owned model in singular (in this case getProfile). Here's an example:

Set up the hasMany relationship by calling 'add' plus the name of the owned model in singular (in this case addAccount). Retrieve the associated items with a call to 'get' plus the name of the owned model in plural (in this case getAccounts). An example:

var user = User.create({
  login: 'asdf'
, password: 'zerb'
, confirmPassword: 'zerb'
});
user.save(function (err, data) {
  if (err) {
    throw err;
  }
  user.addAccount(Account.create({}));
  user.addAccount(Account.create({}));
  user.save(function (err, data) {
    if (err) {
      throw err;
    }
    user.getAccounts(function (err, data) {
      if (err) {
        throw err;
      }
      console.log('This number should be 2: ' + data.length);
    });
  });
});
var user = User.create({
  login: 'asdf'
, password: 'zerb'
, confirmPassword: 'zerb'
});
user.save(function (err, data) {
  var profile;
  if (err) {
    throw err;
  }
  profile = Profile.create({});
  user.setProfile(profile);
  user.save(function (err, data) {
    if (err) {
      throw err;
    }
    user.getProfile(function (err, data) {
      if (err) {
        throw err;
      }
      console.log(profile.id ' is the same as ' + data.id);
    });
  });
});

A belongsTo relationship is created similarly to a hasOne: by calling 'set' plus the name of the owner model in singular (in this case setAuthor). Retrieve the associated item by using 'get' plus the name of the owner model in singular (in this case getAuthor). Here's an example:

var book = Book.create({
  title: 'How to Eat an Entire Ham'
, description: 'Such a poignant book. I cried.'
});
book.save(function (err, data) {
  if (err) {
    throw err;
  }
  book.setAuthor(Author.create({
    familyName: 'Neeble'
  , givenName: 'Leonard'
  }));
  book.save(function (err, data) {
    if (err) {
      throw err;
    }
    book.getAuthor(function (err, data) {
      if (err) {
        throw err;
      }
      console.log('This name should be "Neeble": ' + data.familyName);
    });
  });
});

Removing associations

A similar API is used for removing associations, with the word 'remove' plus the name of the owned model:

User.first({login: 'asdf'}, function (err, user) {
  if (err) {
    throw err;
  }
  // Fetch accounts
  user.getAccounts(function (err, accounts) {
    var originalCount;
    if (err) {
      throw err;
    }
    originalCount = accounts.length;

    // Remove the first account
    user.removeAccount(accounts[0]);
    // Save the user
    user.save(function (err) {
      if (err) {
        throw err;
      }
      // Fetch accounts again
      user.getAccounts(function (err, accounts) {
        if (err) {
          throw err;
        }
        Console.log(accounts.length + ' should be one less than ' +
            originalCount);
      });
    });
  });
});

Note that this does not remove the associated item itself -- only the association linking it to the owner object.

'Through' associations

'Through' associations allow a model to be associated with another through a third model. A good example would be a Team linked to Players through Memberships.

var Player = function () {
  this.property('familyName', 'string', {required: true});
  this.property('givenName', 'string', {required: true});
  this.property('jerseyNumber', 'string', {required: true});

  this.hasMany('Memberships');
  this.hasMany('Teams', {through: 'Memberships'});
};

var Team = function () {
  this.property('name', 'string', {required: true});

  this.hasMany('Memberships');
  this.hasMany('Players', {through: 'Memberships'});
};

var Membership = function () {
  this.belongsTo('User');
  this.belongsTo('Team');
};

The API for this is the same as with normal associations, using the set/add and get, with the appropriate association name (not the model name). For example, in the case of the Team adding Players, you'd use addPlayer and getPlayer.

Named associations

Sometimes you need mutliple associations to the same type of model (e.g., I have lots of Friends and Relatives who are all Users). You can accomplish this in Model using named associations:

var User = function () {
  this.property('familyName', 'string', {required: true});
  this.property('givenName', 'string', {required: true});

  this.hasMany('Kids', {model: 'Users'});
};

The API for this is the same as with normal associations, using the set/add and get, with the appropriate association name (not the model name). For example, in the case of Kids, you'd use addKid and getKids.

Named 'through' associations

If one of your named associations of a model is 'through' another model, such as a join table, it is necessary that the association's name is the same for the model declaring the through association as it is for the model who the association is through.

For example, a team may have many players, but may also have many coaches.

var Team = function(){
  this.hasMany('Players');
  this.hasMany('Coaches', {through: 'TeamCoaches', model: 'Players'});
};
var TeamCoaches = function(){
  this.belongsTo('CoachedTeam', {model: 'Team'});
  this.belongsTo('Coach', {model: 'Player'});
}
var Player = function(){
  this.hasMany('Teams');
  this.hasMany('CoachedTeams', {through: 'TeamCoaches', model: 'Team'});
}

Here a Team has many Players, but also has many Coaches, and we have an inverse relationship set up as well so that a Player has many Teams but also has many CoachedTeams.

Querying

Model uses a simple API for finding and sorting items. Again, it should look familiar to anyone who has used a similar ORM for looking up records. The only wrinkle with Model is that the API is (as you might expect for a NodeJS library) asynchronous.

Methods for querying are static methods on each model constructor.

Finding a single item

Use the first method to find a single item. You can pass it an id, or a set of query parameters in the form of an object-literal. In the case of a query, it will return the first item that matches, according to whatever sort you've specified.

var user;
User.first({login: 'alerxst'}, function (err, data) {
  if (err) {
    throw err;
  }
  user = data;
  console.log('Found user');
  console.dir(user);
});

Collections of items

Use the all method to find lots of items. Pass it a set of query parameters in the form of an object-literal, where each key is a field to compare, and the value is either a simple value for comparison (equal to), or another object-literal where the key is the comparison-operator, and the value is the value to use for the comparison.

In SQL adapters, you can pass a callback to the all method if you want the results buffered and returned all at once, or steam the results using events.

Using a callback

Pass your callback function as a final argument. Callbacks use the normal (err, data) pattern. Here's an example:

var users
  , dt;

dt = new Date();
dt.setHours(dt.getHours() - 24);

// Find all the users created since yesterday
User.all({createdAt: {gt: dt}, function (err, data) {
  if (err) {
    throw err;
  }
  users = data;
  console.log('Found users');
  console.dir(users);
});

Streaming results with events (SQL adapters only)

The all method returns an EventedQueryProcessor which emits the normal 'data', 'end', and 'error' events. Each 'data' event will return a single model-item.

NOTE: Do not pass a callback to the all method if you're streaming -- passing a callback will cause the results to be buffered internally. If you need something to happen when the stream ends, use the 'end' event.

var users
  , dt
  , processor;

dt = new Date();
dt.setHours(dt.getHours() - 24);

// Find all the users created since yesterday
processor = User.all({createdAt: {gt: dt});
processor.on('data', function (user) {
  console.log('Found user');
  console.dir(user);
});
processor.on('error', function (err) {
  console.log('whoops');
  throw err;
});
processor.on('end', function () {
  console.log('No more users');
});

Examples of queries

Here are a few more examples of queries you can pass to the all method:

// Where "foo" is 'BAR' and "bar" is not null
{foo: 'BAR', bar: {ne: null}}
// Where "foo" begins with 'B'
{foo: {'like': 'B'}}
// Where foo is less than 2112, and bar is 'BAZ'
{foo: {lt: 2112}, bar: 'BAZ'}

Comparison operators

Here is the list of comparison operators currently supported:

  • eql: equal to
  • ne: not equal to
  • gt: greater than
  • lt: less than
  • gte: greater than or equal
  • lte: less than or equal
  • like: like

A simple string-value for a query parameter is the same as 'eql'. {foo: 'bar'} is the same as {foo: {eql: 'bar'}}.

For case-insensitive comparisons, use the 'nocase' option. Set it to true to affect all 'like' or equality comparisons, or use an array of specific keys you want to affect.

// Zoobies whose "foo" begin with 'b', with no case-sensitivity
Zooby.all({foo: {'like': 'b'}}, {nocase: true}, ...
// Zoobies whose "foo" begin with 'b' and "bar" is 'baz'
// The "bar" comparison will be case-sensitive, and the "foo" will not
Zooby.all({or: [{foo: {'like': 'b'}}, {bar: 'baz'}]}, {nocase: ['foo']},

More complex queries

Model supports combining queries with OR and negating queries with NOT.

To perform an 'or' query, use an object-literal with a key of 'or', and an array of query-objects to represent each set of alternative conditions:

// Where "foo" is 'BAR' OR "bar" is 'BAZ'
{or: [{foo: 'BAR'}, {bar: 'BAZ'}]}
// Where "foo" is not 'BAR' OR "bar" is null OR "baz" is less than 2112
{or: [{foo {ne: 'BAR'}}, {bar: null}, {baz: {lt: 2112}}]}

To negate a query with 'not', simply use a query-object where 'not' is the key, and the value is the set of conditions to negate:

// Where NOT ("foo" is 'BAR' and "bar" is 'BAZ')
{not: {foo: 'BAR', bar: 'BAZ'}}
// Where NOT ("foo" is 'BAZ' and "bar" is less than 1001)
{not: {foo: 'BAZ', bar: {lt: 1001}}}

These OR and NOT queries can be nested and combined:

// Where ("foo" is like 'b' OR "foo" is 'foo') and NOT "foo" is 'baz'
{or: [{foo: {'like': 'b'}}, {foo: 'foo'}], not: {foo: 'baz'}}

Options: sort, skip, limit

The all API-call for querying accepts an optional options-object after the query-conditions for doing sorting, skipping to particular records (i.e., SQL OFFSET), and limiting the number of results returned.

Sorting

Set a 'sort' in that options-object to specifiy properties to sort on, and the sort-direction for each one:

var users
// Find all the users who have ever been updated, and sort by
// creation-date, ascending, then last name, descending
User.all({updatedAt: {ne: null}}, {sort: {createdAt: 'asc', lastName: 'desc'}},
    function (err, data) {
  if (err) {
    throw err;
  }
  users = data;
  console.log('Updated users');
  console.dir(users);
});

Simplified syntax for sorting

You can use a simplified syntax for specifying the sort. The default sort-direction is ascending ('asc'), so you can specify a property to sort on (or multiple properties as an array) if you want all sorts to be ascending:

// Sort by createdAt, ascending
{sort: 'createdAt'}
// Sort by createdAt, then updatedAt, then lastName,
// then firstName -- all ascending
{sort: ['createdAt', 'updatedAt', 'lastName', 'firstName']}

Skip and limit

The 'skip' option allows you to return records beginning at a certain item number. Using 'limit' will return you only the desired number of items in your response. Using these options together allow you to implement pagination.

Remember that both these option assume you have your items sorted in the desired order. If you don't sort your items before using these options, you'll end up with a random subset instead of the items you want.

// Returns items 501-600
{skip: 500, limit: 100}

Eager loading of associations (SQL adpaters only)

You can use the 'includes' option to specify second-order associations that should be eager-loaded in a particular query (avoiding the so-called N + 1 Query Problem). This will also work for 'through' associations.

For example, with a Team that hasMany Players through Memberships, you might want to display the roster of player for every team when you display teams in a list. You could do it like so:

var opts = {
  includes: ['players']
, sort: {
    name: 'desc'
  , 'players.familyName': 'desc'
  , 'players.givenName': 'desc'
  }
};
Team.all({}, opts, function (err, data) {
  var teams;
  if (err) {
    throw err;
  }
  teams = data;
  teams.forEach(function (team) {
    console.log(team.name);
    team.players.forEach(function (player) {
      console.log(player.familyName + ', ' + player.givenName);
    });
  });
});

Sorting results

Notice that it's possible to sort the eager-loaded associations in the above query. Just pass the association-names + properties in the 'sort' property.

In the above example, the 'name' property of the sort refers to the team-names. The other two, 'players.familyName' and 'players.givenName', refer to the loaded associations. This will result in a list where the teams are initially sorted by name, and the contents of their 'players' list have the players sorted by given name, then first name.

Checking for loaded associations

The eagerly fetched association will be in a property on the top-level item with the same name as the association (e.g., Players will be in players).

If you have an item, and you're not certain whether an association is already loaded, you can check for the existence of this property before doing a per-item fetch:

if (!someTeam.players) {
  someTeam.getPlayers(function (err, data) {
    console.dir(data);
  });
}

Model JavaScript ORM copyright 2112 mde@fleegix.org.

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