EXPRESS - MONGODB ATLAS

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How to use

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Install

#clone the repo

docker-compose up	//Sets up a local instance of MongoDB
cd server
npm install

Create .env file at server/

PORT=4000
MONGO_URI=mongodb://mongouser:mongo@localhost:27017/mydb?authSource=admin

Note: Installation includes a seeding script which will run automatically as part of docker compose.

Shutdown

docker-compose down

#Check volumes/images for regular cleanups
docker volumes prune
docker image prune

Expand for a fully containerized install

Uncomment the following code from

docker-compose.yml

server:
build: ./server
container_name: express-server
ports:
- "4000:4000"
volumes:
- ./server:/app:ro
- /server/node_modules
depends_on:
- mongo

Change the database-host reference in .env file to the container-name for server

MONGO_URI=mongodb://mongouser:mongo@mongo:27017/mydb?authSource=admin

Run the container

docker-compose up --build -v

Mongo Aggregation Example

When a new user (e.g. shinobi) is added with keys which are existing in the database, mongodb will call an auto-aggregate function using pipelines which trigger on changeStream() listeners.

Example

1. Trigger seedShinobi.js seed function.

node db/seed/seedShinobi.js

Sample input

{
	shinobi_name: "Naruto",
	designation: "Chunin",
	clan: [
		{
			name: "Uzumaki"
		},
	],

	village: [
		{name: "Konoha"},
	],
	jutsu: [
		{name: "Kagebunshin no jutsu"},
		{name: "Rasengan"},
		{name: "Eroke no jutsu"},
	],
}

After Aggregation (Aggregation pipeline is triggered as an async waterfall function. Use the returned id from seeding function to retrieve the records)

{
shinobi_name: "Naruto",
designation: "Chunin",
clan: [
		{
			name: "Uzumaki",
			population: 2,
		},
	],
village: [
		{
			name: "Konoha",
			country: "Fire",
		},
	],
jutsu: [
		{
			name: "Kagebunshin no jutsu",
			description: "Multliplies self based on chakra",
			rank: 100,
		},
		{
			name: "Rasengan",
			description: "Concentrated ball of chakra.",
			rank: 5,
		},
		{
			name: "Eroke no jutsu",
			description: "Transform into a sexy partner.",
			rank: 999,
		},
	],
}

Mongo pipelines with auto-aggregate

{
        $lookup: {
          from: "clans",
          localField: "clan.name",
          foreignField: "name",
          as: "clan",
        },
      },
      {
        $lookup: {
          from: "villages",
          localField: "village.name",
          foreignField: "name",
          as: "village",
        },
      },
      {
        $lookup: {
          from: "jutsus",
          localField: "jutsu.name",
          foreignField: "name",
          as: "jutsu",
        },
      },
      {
        $merge: {
          into: "shinobis",
          // on: "_id",
          whenMatched: "merge",
          whenNotMatched: "insert",
        },
      },