nekodb

NekoDB

Tiny ODM for MongoDB. The Ne comes from NeDB, and ko refers to the Japanese diminuitive "ko" (小) or little.

Project goals

• To build the simplest, easiest to use ODM
• Stay as close to MongoDB syntax as possible
  • Provide model validation and model referencing
  • Beyond that, just provide a thin wrapper over the native functionality
• Support NeDB and MongoDB with an identical interface
• Promisify NeDB: no callback hell, only lovely Promises

No database? No problem!

NekoDB comes with NeDB built in, so you can access a Mongo-like database, without actually installing or running a database at all. NeDB is suitable for datasets in the range of tens of thousands of documents. For larger datasets, it is recommended you upgrade to MongoDB.

Quick Intro

Connecting and creating schemas

const ko = require('nekodb')

ko.connect({
    client: 'nedb',
    filepath: __dirname + '/db'
})

ko.models({
    Celebrity: {
        name: ko.String[50],
        age: ko.Number.integer(),
        birthday: ko.Date,
        instagram: ko.String[30],
        followers: ko.Number
    },
    Family: {
        name: ko.String,
        members: [ko.models.Celebrity],
        city: ko.String
    }
})

Connect to a backend, and then register your models by calling ko.models and passing an object containing the schemas for each model.

Creating a model

const celebrity = ko.models.Celebrity.create({
    name: 'Kim Kardashian West',
    age: 37,
    birthday: new Date('1980-10-21'),
    instagram: '@kimkardashian',
    followers: 1080000
})

celebrity.save().then(instance => {
    console.log(instance)
    // instance will have been assigned an _id
})

Create a model instance with the create method. To save the instance to the database, call save.

Finding models

ko.models.Celebrity.find({}).then(instances => {
    console.log(instances)
})

ko.models.Celebrity.findOne({name: 'Kanye West'}).then(instance => {
    console.log(instance)
})

Retrieve models from the database with find, findOne, and findById methods.

Updating a model

ko.models.Celebrity.findOne({name: 'Kim Kardashian'}).then(instance => {
    instance.name = 'Kim Kardashian West'
    return instance.save()
})

Retrieving a model or models returns model instances, so to update the model, update the fields on the model and then call save.

Deleting models

ko.models.Celebrity.deleteOne({name: 'Johnny Depp'}).then(deletedCount => {
    console.log(deletedCount)
})

Delete models with the deleteOne, deleteMany, or deleteById methods.

Populating references

ko.models.Family.findOne({name: 'West'}).join().then(instances => {
    console.log(instances)
})

With each reference in the array replaced with the full instance of the referenced document, the result might look something like this:

Instance {
    name: 'West',
    members: [ Instance {
        _id: 'ps30L4dHbv9rLTln',
        name: 'Kim Kardashian West',
        age: 37,
        birthday: 1980-10-21T00:00:00.000Z,
        instagram: '@kimkardashian',
        followers: 1080000 },

        Instance {_id: 'ps30L4dHbv9rLTlo',
        name: 'Kanye West',
        age: 40,
        birthday: 1977-06-08T00:00:00.000Z,
        instagram: '@privatekanye',
        followers: 406000 } ],
    city: 'Los Angeles, CA' }

Detailed Guide

Connecting to a backend

Before you can do anything else, you must connect to a backend. There are two options available: NeDB and MongoDB. To connect, call ko.connect and supply a configuration.

NeDB

Supply a file path where NeDB will store the database files. Alternatively, set 'inMemory' to true to use the in-memory client, without persisting the database.

ko.connect({
    client: 'nedb',
    filepath: __dirname + '/path/to/db'
})

or

ko.connect({
    client: 'nedb',
    inMemory: true
})

MongoDB

Supply the information necessary to connect to MongoDB, as well as the name of the database to use.

You can omit username and password if they're not needed to connect.

Note that to use the MongoDB client, you must also install the optional npm package mongodb.

ko.connect({
    client: 'mongodb',
    username: 'root',
    password: 'mongopassword',
    address: 'localhost:27017',
    database: 'nekodb'
})

or

ko.connect({
    client: 'mongodb',
	url: 'mongodb://username:password@localhost:27017/nekodb'
})

You don't need to supply a username or password if they are not required to connect.

Note that you don't have to wait for a callback after connecting. You can just start issuing commands, which will be queued up and executed once the database connection has been established.

Though they are executed in order, there's no way to guarantee that they finish in order. If you need the results of one call in a subsequent call you should still use a Promise chain to order your calls.

Creating schemas

To create a schema you can call ko.models as in the Quick Intro to create all your schemas at once, or individually with ko.Model. Since typing ko.models every time you want to access a model can quickly become tiresome, you can create them one at a time and assign them each to a variable.

const User = ko.Model('User', {
    username: ko.String,
    password: ko.String,
    email: ko.Email
})

The first argument to ko.Model is the name of the model, which is the name of the collection and the property name with which it will be attached to ko.models.

In this example, we can access the newly created model either by its variable name User, or at ko.models.User.

The second argument is the schema to use, which is supplied as an object. The object's keys are the field names, and its values are Ko typeclasses. Typeclasses will check to ensure instance values are of the correct type, and can also perform additional validation and set values, as we will see shortly.

Builtin types

The supported JavaScript types are:

• String
• Number
• Boolean
• Date
• Array
• Object
• null

We refer to them by their Ko Typeclasses. The available typeclasses are:

• ko.String
• ko.Number
• ko.Boolean
• ko.Date
• ko.Array
• ko.Option
• ko.Document
• ko.null

Shorthands

Rather than using ko.Array, ko.Option, ko.Document, or ko.null, directly, there are shorthands to create them.

To specify that a field should contain an array of a certain type, pass an array containing one typeclass. To specify a field that can contain varying types, pass an array containing more than one typeclass. These can be nested. To create an array whose elements can be of differing types, supply an array containing the array of options.

const Model = ko.Model('Model', {
    array: [ko.Number],              // field must be an array of numbers
    option: [ko.Number, ko.String]   // field must be a number or a string
    optArr: [[ko.Number, ko.String]] // field must be an array of strings or numbers
})

To specify that a field should be null, you can just use null in lieu of a typeclass. To make a field optional, you can either pass an option array containing the desired type and null, or using the typeclass method optional

const Optional = ko.Model('Optional', {
    optionalString: [ko.String, null],
    altOptionalStr: ko.String.optional()
    // these accomplish the same thing
})

Embedded documents

To specify that a field should contain an embedded document, supply an object: this object will look a lot like a schema, with specified field names and typeclasses. This is the type against which values will be checked.

const Embedded = ko.Model('Embedded', {
    document: {
        embeddedField: ko.String,
        embeddedNum: ko.Number
    }
})

In this example, any instance of the Embedded model must contain an object in the document field and that object must contain the fields embeddedField and embeddedNum.

Constants

To specify that a field should contain a constant (and to assign it that value) you can supply a number, string, boolean, or Date.

const Constants = ko.Model('Constants', {
    string: 'always this string',
    number: 0,
    boolean: true,
    date: new Date('2018-02-25')
})

Length limited strings

To specify that a string should have a maximum length, you can use square brackets on ko.String passing in the desired maximum length.

const MaxLength = ko.Model('MaxLength', {
    string: ko.String[10]
})

Validators

In addition to checking the type, each builtin typeclass contains a number of validator methods that can perform more specific validation. Length limiting strings is one example. These are called as methods on the typeclass, and return a new typeclass.

Since the returned result is a typeclass, you can continue to call methods on it in a chain.

You may find it more readable to define your extended typeclasses above your model rather than putting the whole complicated thing into the schema.

// contains only our desired characters
const Username = ko.String.match(/^[a-zA-Z0-9_\-\.~[\]@!$'()\*+;,= ]{2,30}$/)

// contains at least 1 lowercase, 1 uppercase, and one number
const Password = ko.String.minlength(8)
                          .match(/[a-z]/)
                          .match(/[A-Z]/)
                          .match(/\d/)

const User = ko.Model('User', {
    username: Username, 
    password: Password,
    email: ko.Email
})


// only integers from 1 through 10
const Rating = ko.Number.integer().range(1, 10)

const MovieReview = ko.Model('MovieReview', {
    author: User,
    movie: ko.String[100],
    rating: Rating
    body: ko.String,
})

The full list of validators available is found below in the API reference.

Values

A method can also cause the typeclass to set a value when the model is created. Any typeclass can have a default value, set with the default method. You can set the value to the current time and date with ko.Date.now().

const Member = ko.Model('Member', {
    name: ko.String,
    bio: ko.String.default('This user has not set a bio')
    joined: ko.Date.now()
})

References

To specify that a field should contain a reference to a model, you can simply supply that Model.

const Author = ko.Model('Author', {
    name: ko.String,
    email: ko.Email
})

const BlogPost = ko.Model('BlogPost', {
    title: ko.String,
    body: ko.String,
    author: Author,
    postDate: ko.Date.today()
})

To reference a Model that has not been created yet, or to reference it without access to the variable it was saved to (for instance, if requiring it would cause a circular dependency) you can refer to the Model by its name on ko.models

const Blog = ko.Model('Blog', {
    owner: ko.models.Author,
    posts: [ko.models.BlogPost],
})

Embedding models

In addition to referencing a model by its _id, you can also embed a copy of it in another document to avoid having to perform a join when you often or always need the data of the reference. To do so, call the embed method on a Model.

const Comment = ko.Model('Comment', {
    author: ko.models.Author,
    body: ko.String
    date: ko.Date.now()
})

const BlogPost2 = ko.Model('BlogPost2', {
    title: ko.String,
    body: ko.String,
    author: Author,
    postDate: ko.Date.today()
    comments: [Comment.embed()]
})

By default, embedding a document saves a copy of it in its collection. To avoid this, use embedOnly. Currently, updating and saving an embedded model that is embedded will update it in its collection, but saving an embedded model directly will not update the models it is referenced in. This will change in a future version. For now, you can consider embedded models you find on their own read-only.

Utility Typeclasses

There some built-in utility typeclasses, which perform common validation. They are:

• ko.Email a String containing a valid email
• ko.URL a String containing a valid URL
• ko.URL.Relative a String containing a valid URI to a relative path on the same server

Open an issue if you can think of other utility typeclasses that should be built-in.

Creating models

To create a new model, first create a model instance with <Model>.create(). Calling create without an argument creates a blank model, with all its fields set to undefined. If you have all the data handy when you're creating it, you can pass an object to create whose values will be copied over.

Once created and populated, your instance is ready to be saved to the database. You do so by calling <instance>.save() which returns a Promise. If all the fields were valid and the save completed successfully, the promise will be fulfilled with the same instance you created before but with an _id assigned by the database. If an _id is provided explicitly, it will use that instead of one assigned by the database.

If the save was not successful, the promise will be rejected. If it simply failed validation, the promise will be rejected with an object containing all the offending fields and their values. If some other error occurred, the promise will be rejected with that error.

const user1 = ko.models.User.create()

user1.username = 'nekodb'
user1.password = 'Password123'
user1.email = '[e-mail]'

// or

const user2 = ko.models.User.create({
    username: 'nekodb',
    password: null,
    email: '[e-mail]'
})

user1.save().then(user => {
    console.log(user._id)
    // generated _id from database
})

user2.save().catch(errors => {
    console.log(errors)
    // errors will contain the password field,
    // since it doesn't contain a String as was required
})

Finding models

To retrieve models from the database use the Model find, findOne, or findById methods. Each of these arguments takes a MongoDB query object as its first argument. This is a paper thin wrapper over the client's own find methods, so the syntax is literally identical to that of the client you are using.

find returns an array of models, findOne and findById return a single model. Every find method returns a Promise that resolves to Instances like those returned by create().

const Celebrity = ko.models.Celebrity

Celebrity.find({age: 37}).then(celebs => {
    celebs.forEach(celeb => {
        console.log(celeb)
    })
})
// returns all celebrity models with age = 37

Celebrity.findOne({name: 'Kanye West'}).then(kanye => {
    console.log(kanye)
})
// finds one model whose name is 'Kanye West'

Celebrity.findById('ps30L4dHbv9rLTln').then(celeb => {
    console.log(celeb)
})
// finds the model with the given _id

Query syntax

The basic structure of a query is an object with the fields to compare and either an expected value or comparison operators ($lt, $lte, $gt, $gte, $in, $nin, $ne). These can be combined with logical operators $or, $and, $not and $where.

Regex matches can be performed using the $regex operator.

Basic queries

Basic queries look for documents whose fields match the values you specify. An example would be {firstname: 'John', lastname: 'Smith'} which returns all models named "John Smith".

Using {} as a query returns all the documents.

Comparison and logical operators

ko.models.Celebrity.find({age: {$gte: 40}}).then(celebs => {
    celebs.forEach(celeb => console.log(celeb))
})
// logs all celebrities at least 40 years old

const start2017 = new Date('2017-01-01')
const end2017 = new Date('2018-01-01')

ko.models.BlogPost.find({title: {$regex: /JavaScript/i},
                         postDate: {$and: [{$gte: start2017}, {$lt: end2017}]}}).then(posts => {
    posts.forEach(post => console.log(post))
})

// we specified two fields in this query: title and postDate
// logs all blog posts whose titles contain "JavaScript" posted in 2017

For a more in depth explanation of the syntax, please refer to the documentation of the client you are using.

• NeDB
• MongoDB

Actually, if you're completely unfamiliar with MongoDB query syntax, I recommend looking at NeDB's documentation first, even if you're using MongoDB, as it provides a gentler introduction and makes notes of where the syntax differs from MongoDB's so you won't get mixed up.

Projections

The second, optional argument to the find family of methods is the projections you want to perform. It uses MongoDB's syntax for projections, that is, an object containing fields, and values 0 or 1 to either exclude or include fields. So for instance {a: 1, b: 1} would include only fields a and b, and {c: 0} would include all fields except for c. You can't mix the two, except for _id which is by default always returned but can be omitted, even when using 1s.

Since this results in an incomplete object that would no longer pass validation, projections are a one way trip, and do not return a model instance, rather just returning a plain object.

ko.models.BlogPost.find({}, {title: 1, _id: 0}).then(titles => {
    console.log(titles)
    // objects that only contain the title field
})

Cursor methods

Sorting and paginating is done the same way as it's done in MongoDB and NeDB, using a Cursor object returned by find. The cursor has methods to alter the results it will return.

Once you've modified the query as needed, execute it by calling then on it like it's a Promise, or forEach like it's an array.

Sorting

Sort the results you get back by calling the sort method on a cursor. Sort takes an object as an argument which specifies the fields and which direction to sort them in. An example would be {name: 1} which sorts by name in ascending order or {name: 1, age: -1} which would sort first by name in ascending order, then by age in descending order.

Paginating

By combining the skip and limit cursor methods, you can accomplish pagination.

ko.models.Comment.find({author: '3Pipc0uSq1cXqlgE'}).sort({postDate: 1}).skip(0).limit(5).then(comments => {
    console.log(comments)
    // first 5 comments
    return ko.models.Comment.find({author: '3Pipc0uSq1cXqlgE'}).sort({postDate: 1}).skip(5).limit(5)
}).then(comments => {
    console.log(comments)
    // next 5 comments
})
// etc.

Joining references

The cursor also has a method not found in MongoDB or NeDB called join. By calling join with an array of field names, the references contained in those field names will be replaced with the full models that they reference. Calling it without an argument joins all references on the model.

Calls to findOne and findById can also be joined this way, calling join before then.

Model instances also have a join method which will perform the join on the instance, returning a Promise that resolves to the instance with its references replaced.

const Blog = ko.Model('Blog', {
    owner: ko.models.Author,
    posts: [ko.models.BlogPost],
})

Blog.find({}).join().then(blogs => {
    console.log(blogs)
    // every blog in the array contains a full Author model in the owner field,
    // and an array of full BlogPost models in the posts field
})

Updating models

Updating is performed by first finding the model(s) to modify and then, since the find methods return Instances, editing the model(s) and then calling save().

Only fields that have been updated will be revalidated and saved. Modifications to array and document fields are also considered.

BlogPost.findOne({title: 'Asynchronous JavaSrcipt'}).then(blogpost => {
    blogpost.title = 'Asynchronous JavaScript'
    return blogpost.save()
}).then(() => {
    // continue processing
})

const Player = ko.Model('Player', {
    username: ko.String,
    gold: ko.Number.default(0)
})

Player.find({}).then(allPlayers => {
    const saves = allPlayers.map(player => {
        player.gold += 100
        return player.save()
    })

    return Promise.all(saves)
}).then(() => {
    // continue processing
})

Array operator methods

Using Array prototype methods (like .push, .splice, etc.) causes the whole array to be replaced when saving to the database. Same goes for setting the field to a new array. To work more efficiently with arrays, you can use MongoDB's array manipulation update operators $push, $pop, $addToSet, and $pull, which are exposed as special methods on any array field.

$push

Adds element(s) to the array. You can pass in either a single element or an array of elements as the first argument to $push.

You can use the modifiers $slice and $position to affect the outcome of the push. They are supplied as properties on an object as the second argument to $push.

• $slice limits the length of the array to a certain number, cutting off the end of the array if its length exceeds the amount in $slice
• $position specifies the position at which to insert the elements. 0 inserts at the beginning of the array.

$pop

Removes the first or last element of an array. The argument passed is 1 or -1 which removes the last or first element respectively.

$addToSet

Adds element(s) to the array, but does not add duplicate values. You can pass in either a single element or an array of elements. For objects, performs a deep-equal comparison when considering whether an element is a duplicate.

$pull

Pulls value(s) from the array. You can pass in either a value to pull or an array of values to pull.

MongoDB (and NeDB) allow you to pass a query to $pull rather than a value. While this will also work here, NekoDB does not yet contain a full-blown query processor, and as such your instance will go out of sync, with those values apparently not pulled from the array, though they will be when the instance is saved. If you specified that the array should not be empty, using a query may result in the array being empty after all but validation will not catch it. It's also not tested. Be careful when passing a query to $pull, and avoid it if possible.

const Student = ko.Model('Person', {
	name: ko.String,
	classes: [ko.String]
})

Student.create({
	name: 'Joanne',
	classes: ['Calculus', 'Poetry', 'Databases']
}).save().then(student => {
	student.classes.$push('Biology')
	return student.save()
}).then(student => {
	student.classes.$push(['Greek Drama', 'Greek Comedy'], {
		$position: 0,
		$slice: 4,
	})
	// classes will now contain ['Greek Drama', 'Greek Comedy', 'Calculus', 'Poetry']
	return student.save()
}).then(student => {
	// 'Poetry' will not be added to the array as it already exists
	student.classes.$addToSet(['Poetry', 'Nuclear Physics'])
	return student.save()
}).then(student => {
	// removes the last element of the array. $pop(-1) removes the first.
	student.classes.$pop(1)
	return student.save()
}).then(student => {
	student.classes.$pull('Calculus')
	student.save()
})

Saving joined models

If you perform a join on a model, you may note that the model should no longer pass validation: where it expects a reference, it now contains an object. However, you can still edit your model and save it without any issues. References that have been joined will be coerced back into references prior to saving.

You can also make changes to a reference while it is joined and have those changes be saved using the saveRefs() method. To perform both saveRefs() and save() in one method call, you can use saveAll()

Creating models with saveRefs() / saveAll()

As saveRefs just calls save() on the reference instances, saveAll() can also be used to create an entirely new model to be saved to the database. This way you can create your models and references together in one action.

ko.models.Blog.create({
    owner: {
        name: 'Niko D.B.',
        email: '[e-mail]'
    },
    posts: []
}).saveAll().then(blog => {
    console.log(blog.owner)
    // this will be the _id of the newly created Author model
    
    blog.posts.push({
        title: 'My first blog',
        body: 'The content of the blog post',
        author: blog.owner
    })

    return blog.saveAll()
}).then(blog => {
    console.log(blog.posts)
    // now contains the _id of the newly created BlogPost
})

Where is Model.update() ?

Currently you can't use either client's native update methods as they would bypass validation. This will be supported in a later version.

Counting Models

To count the number of documents matching a query, use the Model count method, which takes the same kind of query as the find methods. count returns a Promise that resolves to the number of models that matched the query.

ko.models.Author.count({}).then(count => {
    console.log(count)
    // logs the total number of Author models
})

Deleting Models

You can delete a model two ways: using the Model methods deleteOne, deleteMany, or deleteById, or by calling delete() on a model instance.

These all return a Promise that resolves to the number of documents deleted by the operation.

ko.models.User.deleteOne({username: 'nekodb'}).then(deletedCount => {
    console.log(deletedCount)
    // this will be 1 if we succeeded
})

ko.models.User.findOne({username: 'milkperil'}).then(user => {
    return user.delete()
}).then(deletedCount => {
    console.log(deletedCount)
    // this will be 1 if we succeeded
})

If predelete or postdelete hooks are specified, they will be run for each instance using any of the methods to delete the model.

Hooks

You can inject code to be run before and after certain steps of saving a model to the database. Your hook will be called with two arguments: the instance and a next() function you call when you're finished with your hook. You can also return a Promise rather than call next().

You can add hooks two ways. First is by including a $$hooks property on your schema when you define your model, where the keys are the names of the hooks to be added and the values are the hooks. Or, you can set a value on the Model object whose property name is one of the names of the hooks.

Hooks can be a function, which will run regardless of what fields have been updated, or an object whose keys are fields, and whose values are the hooks to run only when the specified field is updated. To add a named hook that always runs, use '' as the field name.

For expensive operations, or operations which should not be repeated, you should use a hook object with named hooks to limit when the hooks are run.

oncreate

Runs immediately after a model is created. Used to asynchronously add default values to a model as Typeclass.default() is limited to synchronous code only.

prevalidate

Runs before validation. Can be used to populate fields that are based on other fields.

postvalidate

Runs after validation.

presave

Runs before saving. If you need to modify a field before storing it in the database, you should do it here.

postsave

Runs after a model is saved.

predelete

Runs before a model is deleted.

postdelete

Runs after a model is deleted.

Using presave to encrypt a password

const bcrypt = require('bcrypt')
const saltRounds = process.env.SALTROUNDS

// contains at least 1 lowercase, 1 uppercase, and one number
const Password = ko.String.minlength(8)
                          .match(/[a-z]/)
                          .match(/[A-Z]/)
                          .match(/\d/)

const User = ko.Model('User', {
    username: ko.String.range(2, 30), 
    password: Password,
    $$hooks: {
        presave: {
            password: (user, next) => {
                bcrypt.hash(user.password, saltRounds, function (err, hash) {
                    if (err) {
                        return next(err)
                    }
                    user.password = hash
                    next()
                })
            }
        }
    }
})

User.create({
    username: 'amy',
    password: 'Here is a G00D password'
}).save().then(user => {
    console.log(user.password)
    // this will be encrypted now
    user.username = 'Amy'
    return user.save()
}).then(user => {
    // the save will succeed even though the password is encrypted
})

Here we supply a named presave hook to be run any time the password is updated. Because validation only occurs when a field is updated, even though the new password may or may not pass validation, you can still modify the model and save it as needed. Because we used a named hook (specifying which field it should run on) the password won't end up getting double encrypted.

To update the password, you need only set a new password on the model and the new password will be validated and encrypted.

Indexing

You can specify indexes on fields by adding an $$index field to a schema or by calling createIndex on a Model. Indexes help speed up performance by reducing the amount of elements the database must check, and can also be used to specify uniqueness constraints.

See Indexes in MongoDB for more information on what indexes are and why you might want to use them.

Creating an index directly calls the client's own index creation mechanism, so the full power of MongoDB or NeDB indexes are at your disposal.

const User = ko.Model('User', {
    username: ko.String,
    password: ko.String,
    $$indexes: {
        username: {
            unique: true
        }
    }
})

Now an error will be thrown if we attempt to create two users with the same username.

API Reference

ko

• connect(Object config) Connects to a backend (either NeDB or MongoDB) using supplied config.
• close() Closes a MongoDB connection, and sets own properties to null.
• Model(Object schema) Registers a Model and creates a collection to store it in. Returns a Model. schema has form {fieldname: typeclass, ...}
• models(Object schemas) Registers multiple Models at once. schemas has form {modelname: {schema}, ...}
• models The Models registry. The properties of this object are a way to refer to each Model that has been registered.
• client The currently used backend. Either an instance of MongoClient (not MongoDB's MongoClient) or NeDBClient

Typeclass

These methods are available on all Typeclasses.

• default(value) Sets a default value when a model is created
• optional() Makes a field accept null and undefined as well as the current type. This method should be called last if calling multiple methods.
• constant(value) Sets a default value and ensures that the field actually contains that value.
• validate(Function validator(value)) Adds a validator, which is a function that takes a value and returns true or false
• extend(Function/Object extend) If argument is a function, calls the function with the this context set to the Typeclass. In the function, set value, validator, or for multiple validators, validators. If it is an object, those same fields are copied over.

ko.Number

Instance of Typeclass Specifies that a field must be a Number.

• min(Number min) Specifies a minimum value.
• max(Number max) Specifies a maximum value.
• minx(Number min) Specifies a minimum value, from but not including the minimum.
• maxx(Number max) Specifies a maximum value, up to but not including the maximum.
• range(Number min, Number max) Specifies a range of valid values from min to max.
• naturalRange(Number min, Number max) Specifies a range of values starting from min up to but not including max.
• integer() Specifies that a field should contain only integer values.

ko.String

Instance of Typeclass Specifies that a field must be a String.

• [Number maxlength] Shorthand for specifying a maximum length.
• minlength(Number length) Specifies a minimum length for the value.
• maxlength(Number length) Specifies a maximum length for the value.
• range(Number minlength, Number maxlength) Specifies a range of valid lengths.
• match(Regex pattern) Tests the value against the supplied regular expression.

ko.Boolean

Instance of Typeclass Specifies that a field must be a Boolean.

ko.Date

Instance of Typeclass Specifies that a field must be a JavaScript Date object.

• after(Date minDate) Specifies that the value must occur after minDate
• before(Date maxDate) Specifies that the value must occur before maxDate
• past() Specifies that the value should be before Date.now()
• future() Specifies that the value should be after Date.now()
• range(Date minDate, Date maxDate) Specifies a range of valid dates, from minDate to maxDate
• now() Sets the value to the value of Date.now() at the time of model creation
• today() Sets the value to midnight of the current day when the model is created

ko.null

Instance of Typeclass Specifies that a field should contain null or undefined.

ko.Array(type)

Instance of Typeclass Specifies that a field should contain an Array of the supplied type.

• notEmpty() Specifies that the value array must contain at least one element.

ko.Option(Array types)

Instance of Typeclass Specifies that a field should contain one of the supplied types.

ko.Document(Object schema)

Instance of Typeclass Specifies that a field should contain an object matching the supplied schema.

Model

Created by ko.Model() or ko.models(). Represents a Model based on a supplied schema.

• create([Object document]) Returns a model instance, optionally copying the values of the supplied document
• count(Object query) Returns a Promise that resolves to the number of models matching the supplied MongoDB query.
• deleteById(_id) Deletes one model with the specified _id. Returns a Promise that resolves to the number of models deleted.
• deleteMany(Object query) Deletes all models matching the supplied MongoDB query. Returns a Promise that resolves to the number of models deleted.
• deleteOne(Object query) Deletes the first model matching the supplied MongoDB query. Returns a Promise that resolves to the number of models deleted.
• find(Object query) Finds all models matching the supplied MongoDB query. Returns a Cursor object that can be used to sort, paginate, and join as an extension to the query.
• findById(Object query) Finds one model with the specified _id. Returns a deferred Promise that can be used to join as an extension to the query. Otherwise it behaves like a Promise.
• findOne(Object query) Finds the first model matching the supplied MongoDB query. Returns a deferred Promise that can be used to join as an extension to the query. Otherwise it behaves like a Promise.

---

• reference() Returns a ModelReference object for use in other Models. Simple reference based on _id field. Typically called implicitly when passing a Model to a schema.
• ref() Shorthand for reference()
• embed() Returns a ModelReference object for use in other Models. A reference that includes the reference as an embedded document, and also saves the embedded model to its own collection.
• embedOnly() Returns a ModelReference object for use in other Models. Same as embed() but does not save a copy.

---

• oncreate The oncreate hook. Assign this to run a custom hook when a model is created.
• prevalidate The prevalidate hook. Assign this to run a custom hook before validation.
• postvalidate The postvalidate hook. Assign this to run a custom hook after validation.
• presave The presave hook. Assign this to run a custom hook before saving.
• postsave The postsave hook. Assign this to run a custom hook after saving.
• predelete The predelete hook. Assign this to run a custom hook.
• postdelete The postdelete hook. Assign this to run a custom hook.

---

• createIndex(String field, Object options) Creates an index on the collection that contains the Model. See clients for available options.

Instance

A model instance. An object whose keys are field names and whose values are the field values.

• save() Saves the model to the database, creating an _id if it does not yet exist.
• saveRefs() Saves references that have been joined or embedded into Instances to the database.
• saveAll() Saves the model and its Instance members to the database.
• delete() Deletes the model from the database.
• join([Array fields]) Populates references on the specified fields to their full models. If fields is not supplied, joins all references on the model.
• slice() Returns a simple object (without prototype methods) that contains the data of the model.

Cursor

A cursor object returned by Model.find().

• sort(Object params) Sorts the results of the query by the supplied params. The object contains field names, and a sort direction for each field name: 1 for ascending order, -1 for descending.
• skip(Number count) Skips over the first count models when performing the query.
• limit(Number count) Limits the number of models returned by the query. When used together with skip you can perform pagination.
• join([Array fields]) Populates each model returned by the query, replacing references with the full models they reference. Joins on specified fields. If fields is not supplied, joins all references.
• then(Function callback) Executes the query and returns a Promise that resolves to the found models.
• toArray(Function callback) Alias for then()
• forEach(Function callback) Runs the callback for each model returned by the query, in order.

NeDBClient(Object config)

The NeDBClient config looks like

{
    client: 'nedb',
    [filepath: '/path/to/db/directory'],
    [inMemory: true],
    [autocompactionInterval: Number interval]
}

where one of filepath or inMemory are supplied. Auto-compaction refers to NeDB's option to periodically compact the database file to reduce size. This is measured in ms, and should be at least 5000.

• close() NeDB does not support close, so this method does nothing but issue a warning.
• createIndex(String collection, String fieldName, Object options) Creates an index on the supplied collection and fieldName. Typically called implicitly by Model.createIndex(). The available options are:
  • unique (optional, defaults to false) enforces uniqueness on the field.
  • sparse (optional, defaults to false) does not index documents on which the field is not defined.
  • 'expireAfterSeconds(Number seconds)' Removes documents from the database when the system time exceeds the value of the field + seconds. Documents where the field is not defined or not a date are ignored.

MongoClient(Object config)

The MongoClient config looks like

{
    client: 'mongodb',
    [username: 'username'],
    [password: 'password'],
    [address: 'localhost:27017'],
    [database: 'the_db]',
	[url: 'mongodb://localhost:27017/the_db']
}

You can supply either the pieces of the connection string as properties (username, password, address, and database) or a connection string (url)

• close() Closes the connection to the MongoDB server.
• createIndex(String collection, String fieldName, Object options) Creates an index on the supplied collection and fieldName. Typically called implicitly by Model.createIndex() As it calls createIndex directly on the underlying MongoClient, it supports the full gamut of MongoDB index options.
• client The underlying MongoClient powering the backend. Could be useful for testing.
• db The underlying MongoDB database object. Could be useful for testing.

Testing

Although the project is still in its early stages, the code is reasonably well tested. To run tests, run the command npm test. To test the MongoDB client, in the config.js file in the test directory, change testMongo to true, and supply your MongoDB information.

Contact

Bug reports, feature requests, and questions are all welcome: just open a Github issue and I'll get back to you.