Table of contents

1. Introduction
2. Prerequisites
3. Installation
4. Usage
5. Documentation

Introduction

Mongoopose is very simple and currently provides by far not all of the mongoose api. It wraps mongoose and behaves like an adapter, based on functional programming patterns and Promises to escape the pyramid of doom.

Combining function composition and Promises comes in very handy, when complex database queries make your head hurt. Your code becomes more readable and easier to reason about, because you will start to see how your data flows.

Mongoopose itself has only a few very basic wrapper functions like find, findOne, save and remove, but leaves you with a simple possibility to compose every async task into the pipeline.

Prerequisites

Most likely you would have a basic understanding of functional programming, but happily you do not need it to just use it, because the implementation is very straight forward.

There is no npm dependency as you can see in package.json, because mongoopose uses dependency injection. In a nutshell... it depends on mongoose, which means you also have a MongoDB setup.

Installation

npm install @stejnar/mongoopose

Usage

Enough talking. Here is some code: Simple findOne and update example:

    const mongoopose = require('mongoopose')
    const mongoose = require('mongoose')
    
    // initialize mongoose model
    const userSchema = require('./schema')
    const UserModel = mongoose.model('User', userSchema)
    
    // initialize mongoopose model
    const {compose, Params} = mongoopose
    const User = mongoopose.model(UserModel)
    
    // design the queries
    const selectJon = params => Params({select: {email: '[email protected]'}})
    const updateJon = params => Params({query: {$set: {lifes: 2}}})
    
    // composition reads from left to right
    const pipeline = compose(
        User.findOne(selectJon),
        User.update(updateJon)
    )
    pipeline(Params()) // empty initial params
        .then(params => console.log(params)) // params.user => jon 
        .catch(error => console.error(error))

Login routine with express.js:

router.post('/login', function (req, res) {

    // find user by name and pass as 'user'
    const findUser = params => Params({ select: { name: params.request.name }, as: 'user' })

    // bycrpt compare action for pipeline
    const comparePasswords = (resolve, reject, params) => {
        const { request, user } = params
        bcrypt.compare(request.password, user.password, (err, same) => {
            if (same) {
                const { _id, name } = user
                resolve(params.add(jwt.sign({ _id, name }, 'ssshhhhh secret'), 'token'))
            } else if (err) {
                reject(params.toError({ status: 500 }))
            } else {
                reject(params.toError({ status: 403, message: 'Unequal passwords' }))
            }
        })
    }

    // find additional user data
    const findPhotos = params => Params({ select: { user: params.user._id }, as: 'photos' })

    // initiate pipeline
    const pipeline = compose(
        User.findOne(findUser),
        User.pipe(comparePasswords),
        Photos.find(findPhotos)
    )

    // set initial params
    const params = { request: req.body.payload }

    // handle results or errros
    pipeline(Params(params))
        .then(({ user, token, photos }) => {
            const { _id: id, name } = user
            res.success(
                'Successfully logged in',
                { user: { id, name }, token, photos }
            );
        })
        .catch(res.error)
});

See functors.test.js for more examples

Documentation

• mongoopose
• Model
• Params

mongoopose

mongoopose.model(model)

Parameters:

• model: Mongoose.Model

Returns: Model

mongoopose.compose(...funcs)

You should only pass findById(), findOne(), find(), save(), update(), remove() and/or pipe() Nested arrays are allowed, they will get flattened, keeping the original order.

Parameter:

• funcs: ...function

Returns:

function(Parameters), that returns a Promise

mongoopose.Params

Model

• Model.findById()
• Model.findOne()
• Model.find()
• Model.save()
• Model.update()
• Model.remove()

Note: All methods, but pipe(), take the same input and give the same output. As follows:

Parameter:

• query: function(query = Parameters => Parameters),

  optional and defaults into no Parameters transformation

Returns:

function(Parameters), that returns a Promise

Model.pipe()

Parameter:

function(action), action can be any function that gets resolve, reject and params passed into and calls resolve or reject

Returns:

function(Parameters), that returns a Promise

Params

Params(obj)

Type: Function

Shorthand for new Parameters().assign(obj)

Parameter:

• obj: object

Returns: new Instance of Parameters

Parameters

Paramters.as

Type: String

Default: mongoose.Model.modelName

This is the key with that a queries result gets assigned to Parameters.

Paramters.select

Type: Object

This is the selector that gets passed into mongoose queries.

Paramters.query

Type: Object

This is the update object for Model.update()

Paramters.save

Type: Object

This gets passed into the mongoose model constructor for Model.save().

Paramters.add(result, name)

Parameters:

• result: any,
• name: String, this is the key with that result gets assigned to Parameters

Returns:

Parameters

Parameters.assign(obj)

Type: Function

Resets the Parameters.as key to undefined and merges obj into it.

Parameters:

• obj: any

Returns:

Parameters

Parameters.toError(msg)

Wraps this instance of Parameters into an Error.

Parameters:

• msg: object | string,

Returns:

Error