index.js

const ObjectID = require("mongodb").ObjectID;
const flatten = require("flat").flatten;
const merge = require("lodash.merge");

class CrudService {
	constructor(mongoDB, collectionName) {
		if (!mongoDB) {
			throw new Error("mongoDB is required");
		}
		if (!collectionName) {
			throw new Error("collectionName is required");
		}

		this.collection = mongoDB.collection(collectionName);
		this.hasTimestamps = false;
	}

	marshal(x) {
		return x;
	}

	create(props) {
		var extraFields = this.hasTimestamps ? {
			createdAt: new Date(),
			updatedAt: new Date()
		} : {};
		return this.collection.insertOne(merge(extraFields, props))
		.then(function(it) {
			return it.ops[0];
		})
		.then(this.marshal);
	}

	list(filter) {
		return this.collection.find(flatten(filter || {}))
		.toArray()
		.then(function(list) {
			list.forEach(this.marshal);

			return list;
		}.bind(this));
	}

	show(id) {
		return this.collection.findOne({_id: ObjectID(id)})
		.then(function(x) {
			if (!x) {
				throw new Error("No such record found with ID: " + id);
			}

			return x;
		})
		.then(this.marshal);
	}

	update(id, modifications) {
		var extraFields = this.hasTimestamps ? {
			updatedAt: new Date()
		} : {};

		return this.collection.findOneAndUpdate(
			{_id: ObjectID(id)},
			{
				$set: flatten(merge(extraFields, modifications), {safe: true})
			},
			{
				upsert: false,
        returnOriginal: false //return the modified body
			}
		)
		.then(function(it) {
			if (!it.value) {
				throw new Error("no records found or updated");
			}

			return it.value;
		})
		.then(this.marshal);
	}

	remove(id) {
		return this.collection.findOneAndDelete({_id: ObjectID(id)})
		.then(function(it) {
			if (!it.value) {
				throw new Error("No documents deleted.");
			}

			return it.value;
		})
		.then(this.marshal);
	}

	setMarshaller(marshal) {
		this.marshal = marshal;

		return this;
	}

	enableTimestamps() {
		this.hasTimestamps = true;

		return this;
	}

	static idMarshaller(x) {
		x.id = x._id;
		return x;
	}
}

module.exports = CrudService;