Camouflage

A fork of Camo by scottwrobinson

Jump To

• Why do we need another ODM?
• Advantages
• Install and Run
• Quick Start
  • Connect to the Database
  • Declaring Your Document
    • Embedded Documents
  • Creating and Saving
  • Loading
  • Deleting
  • Counting
  • Hooks
• In the Wild
• Copyright & License

Why do we need another ODM?

Short answer, we probably don't. Camo was created for two reasons: to bring traditional-style classes to MongoDB JavaScript, and to support NeDB as a backend (which is much like the SQLite-alternative to Mongo).

Throughout development this eventually turned in to a library full of ES6 features. Coming from a Java background, its easier for me to design and write code in terms of classes, and I suspect this is true for many JavaScript beginners. While ES6 classes don't bring any new functionality to the language, they certainly do make it much easier to jump in to OOP with JavaScript, which is reason enough to warrent a new library, IMO.

Advantages

So, why use Camo?

• ES6: Although ES6 hasn't hit mainstream Node yet, it will soon (io.js is currently being merged with Node at the time of this writing). With all of these new features coming out soon, Camo is getting a head start in writing tested and proven ES6 code. This also means that native Promises are built-in to Camo, so no more promisify-ing your ODM or waiting for Promise support to be added.
• Easy to use: While JavaScript is a great language overall, it isn't always the easiest for beginners to pick up. Camo aims to ease that transition by providing familiar-looking classes and a simple interface. Also, there is no need to install a full MongoDB instance to get started with the support of NeDB.
• Multiple backends: Camo was designed and built with multiple Mongo-like backends in mind, like NeDB, LokiJS*, and TaffyDB*. With NeDB support, for example, you don't need to install a full MongoDB instance for development or for smaller projects. This also allows you to use Camo in the browser, since databases like NeDB supports in-memory storage.
• Lightweight: Camo is just a very thin wrapper around the backend databases, which mean you won't be sacrificing performance.

* Support coming soon.

Install and Run

To use Camo, you must first have installed io.js 2.0.0 or higher, then run the following commands:

npm install camo --save

And at least ONE of the following:

npm install nedb --save

OR

npm install mongodb --save

Note: Camo currently does not work with Node due to its lack of ES6 features. Node is currently merging with io.js, so hopefully we'll be able to support Node soon.

To run your application using Camo, as of now you must also use the --harmony-proxies flag:

node --harmony-proxies index.js

We show this using the node command instead of iojs since io.js is typically aliased behind node when installed with Mac's Homebrew.

Quick Start

Camo was built with ease-of-use and ES6 in mind, so you might notice it has more of an OOP feel to it than many existing libraries. Don't worry, focusing on object-oriented design doesn't mean we forgot about functional techniques or asynchronous programming. Promises are built-in to the API. Just about every call you make interacting with the database (load, save, delete, etc) will return a Promise. No more callback hell :)

For a short tutorial on using Camo, check out this article.

Connect to the Database

Before using any document methods, you must first connect to your underlying database. All supported databases have their own unique URI string used for connecting. The URI string usually describes the network location or file location of the database. However, some databases support more than just network or file locations. NeDB, for example, supports storing data in-memory, which can be specified to Camo via nedb://memory. See below for details:

• MongoDB:
  • Format: mongodb://[username:password@]host[:port][/db-name]
  • Example: var uri = 'mongodb://scott:abc123@localhost:27017/animals';
• NeDB:
  • Format: nedb://[directory-path] OR nedb://memory
  • Example: var uri = 'nedb:///Users/scott/data/animals';

So to connect to an NeDB database, use the following:

var connect = require('camo').connect;

var database;
var uri = 'nedb:///Users/scott/data/animals';
connect(uri).then(function(db) {
    database = db;
});

Declaring Your Document

All models must inherit from the Document class, which handles much of the interface to your backend NoSQL database.

var Document = require('camo').Document;

class Company extends Document {
    constructor() {
        super('companies');

        this.name = String;
        this.valuation = {
        	type: Number,
        	default: 10000000000,
        	min: 0
        };
        this.employees = [String];
        this.dateFounded = {
        	type: Date,
        	default: Date.now
        };
    }
}

Notice how the schema is declared right in the constructor as member variables. All public member variables (variables that don't start with an underscore [_]) are added to the schema. The 'companies' string sent to the parent constructor tells us the collection name to use for that document type.

Schemas can also be defined using the schema() method. For example, in the constructor() method you could use:

schema({
    name: String,
    valuation: {
        type: Number,
        default: 10000000000,
        min: 0
    },
    employees: [String],
    dateFounded: {
        type: Date,
        default: Date.now
    }
});

Currently supported variable types are:

• String
• Number
• Boolean
• Buffer
• Date
• Object
• Array
• EmbeddedDocument
• Document Reference

Arrays can either be declared as either un-typed (using Array or []), or typed (using the [TYPE] syntax, like [String]). Typed arrays are enforced by Camo on .save() and an Error will be thrown if a value of the wrong type is saved in the array. Arrays of references are also supported.

To declare a member variable in the schema, either directly assign it one of the types above, or assign it an object with options. Like this:

this.primeNumber = {
	type: Number,
	default: 2,
	min: 0,
	max: 25,
	choices: [2, 3, 5, 7, 11, 13, 17, 19, 23],
	index: true
}

The default option supports both values and no-argument functions (like Date.now). Currently the supported options/validators are:

• type: The value's type (required)
• default: The value to be assigned if none is provided (optional)
• min: The minimum value a Number can be (optional)
• max: The maximum value a Number can be (optional)
• choices: A list of possible values (optional)
• match: A regex string that should match the value (optional)
• validate: A 1-argument function that returns false if the value is invalid (optional)
• index: Create an index on the given field if true or a string; a string can be supplied to define the index type, like '2d' (optional)

To reference another document, just use its class name as the type.

class Dog extends Document {
    constructor() {
        super('dogs');

        this.name = String;
        this.breed = String;
    }
}

class Person extends Document {
    constructor() {
        super('persons');

        this.pet = Dog;
        this.name = String;
        this.age = String;
    }
}

Embedded Documents

Embedded documents can also be used within Documents. You must declare them separately from the main Document that it is being used in. EmbeddedDocuments are good for when you need an Object, but also need enforced schemas, validation, defaults, hooks, and member functions. All of the options (type, default, min, etc) mentioned above work on EmbeddedDocuments as well.

var Document = require('camo').Document;
var EmbeddedDocument = require('camo').EmbeddedDocument;

class Money extends EmbeddedDocument {
    constructor() {
        super();

        this.value = {
            type: Number,
            choices: [1, 5, 10, 20, 50, 100]
        };

        this.currency = {
            type: String,
            default: 'usd'
        }
    }
}

class Wallet extends Document {
    constructor() {
        super('wallet');
        this.contents = [Money];
    }
}

var wallet = Wallet.create();
wallet.contents.push(Money.create());
wallet.contents[0].value = 5;
wallet.contents.push(Money.create());
wallet.contents[1].value = 100;

wallet.save().then(function() {
    console.log('Both Wallet and Money objects were saved!');
});

Creating and Saving

To create a new instance of our document, we need to use the .create() method, which handles all of the construction for us.

var lassie = Dog.create({
    name: 'Lassie',
    breed: 'Collie'
});

lassie.save().then(function(l) {
	console.log(l.id);
});

Once a document is saved, it will automatically be assigned a unique identifier by the backend database. This ID can be accessed by either .id or ._id.

If you specified a default value (or function) for a schema variable, that value will be assigned on creation of the object.

An alternative to .save() is .loadOneAndUpdate(query, update, options). This static method will find and update (or insert) a document in one atomic operation (atomicity is guaranteed in MongoDB only). Using the {upsert: true} option will return a new document if one is not found with the given query.

Loading

Both the load and delete methods following closely (but not always exactly) to the MongoDB API, so it should feel fairly familiar. To retrieve an object, you have a few methods available to you.

• .loadOne(query, options) (static method)
• .loadMany(query, options) (static method)

The .loadOne() method will return the first document found, even if multiple documents match the query. .loadMany() will return all documents matching the query. Each should be called as static methods on the document type you want to load.

Dog.loadOne({ name: 'Lassie' }).then(function(l) {
	console.log('Got Lassie!');
	console.log('Her unique ID is', l.id);
});

Deleting

To remove documents fromt the database, use one of the following:

• .delete()
• .deleteOne(query, options) (static method)
• .deleteMany(query, options) (static method)
• .loadOneAndDelete(query, options) (static method)

The .delete() method should only be used on an instantiated document with a valid id. The other three methods should be used on the class of the document(s) you want to delete.

Dog.deleteMany({ breed: 'Collie' }).then(function(numDeleted) {
	console.log('Deleted', numDeleted, 'Collies from the database.');
});

Counting

To get the number of matching documents for a query without actually retrieving all of the data, use the .count() method.

Dog.count({ breed: 'Collie' }).then(function(count) {
	console.log('Found', count, 'Collies.');
});

Hooks

Camo provides hooks for you to execute code before and after critical parts of your database interactions. For each hook you use, you may return a value (which, as of now, will be discarded) or a Promise for executing asynchronous code. Using Promises throughout Camo allows us to not have to provide separate async and sync hooks, thus making your code simpler and easier to understand.

Hooks can be used not only on Document objects, but EmbeddedDocument objects as well. The embedded object's hooks will be called when it's parent Document is saved/validated/deleted (depending on the hook you provide).

In order to create a hook, you must override a class method. The hooks currently provided, and their corresponding methods, are:

• pre-validate: preValidate()
• post-validate: postValidate()
• pre-save: preSave()
• post-save: postSave()
• pre-delete: preDelete()
• post-delete: postDelete()

Here is an example of using a hook (pre-delete, in this case):

class Company extends Document {
    constructor() {
        super('companies');

        this.employees = [Person]
    }

    preDelete() {
        var deletes = [];
        this.employees.forEach(function(e) {
            var p = new Promise(function(resolve, reject) {
                resolve(e.delete());
            });

            deletes.push(p);
        });

        return Promise.all(deletes);
    }
}

The code above shows a pre-delete hook that deletes all the employees of the company before it itself is deleted. As you can see, this is much more convenient than needing to always remember to delete referenced employees in the application code.

Note: The .preDelete() and .postDelete() hooks are only called when calling .delete() on a Document instance. Calling .deleteOne() or .deleteMany() will not trigger the hook methods.

In the Wild

Camo was created during the development of Polymetrics, so this is the only known code in production as of now. It replaced the original models written with Mongoose, which saved us a lot of time and headaches during design and testing.

Are you using Camo in a public-facing app/website? Let us know and we'll post it here!

Copyright & License

Copyright (c) 2015 Scott Robinson

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.