code.Antrikshy | Notes, tinkerings, experiments

Run MongoDB Automatically With Your Node.js Project


Update: The database isn’t closed properly when tests fail, which causes some issues. I kind of gave up on this.

I thought I’d share this quick tip I came up with for my own convenience while working with Node.js. Every time I work on a MongoDB-powered Node.js project, I open a separate tab in Terminal and start MongoDB using the mongod command so that it runs in the background while I develop and test my project.

This is pretty inconvenient to do each time, so I thought I’d automate it as seamlessly as possible. Mostly, I wanted to keep my unit tests as independent from anything else as possible.

So I set up npm scripts like this (in my package.json):

"scripts": {
  "prestart": "mongod --dbpath data --fork --logpath /dev/null",
  "start": "node ./bin/www",
  "poststop": "mongo admin --eval 'db.shutdownServer()' > /dev/null",
  "pretest": "mongod --dbpath data --fork --logpath /dev/null",
  "test": "mocha test",
  "posttest": "mongo admin --eval 'db.shutdownServer()' > /dev/null"
},

In case you’re not sure where to put the above - "scripts" goes as a separate object in the package.json file in your project’s root folder.

Basically what the above does is that it makes sure that MongoDB is running when I run npm test to run my Mocha tests. It also closes the MongoDB server when the tests are completed. This is achieved through the pretest and posttest hooks.

Additionally, I have also created prestart and poststop hooks so that MongoDB also runs when I use npm start. After I’m done working, I close the server using Ctrl + C and run npm stop to cleanly shut the MongoDB server down.

In case you’re interested in what the two commands do:

mongod --dbpath data --fork --logpath /dev/null

The --fork flag starts a mongod process in the background. --logpath /dev/null means that no logs are saved. You can change this if you wish.

mongo admin --eval 'db.shutdownServer()' > /dev/null

The above is equivalent to running the mongo shell interface, entering use admin and executing the command db.shutdownServer(). This is because the Mac version does not support the --shutdown flag. If you are using Linux, you can replace the entire command above with mongod --shutdown and that will probably work. I pipe the output to /dev/null to keep things clean. It also seems to output an error, but it seems to work, so I prefer to suppress it this way.

If someone knows a way to make nodemon run npm start and npm stop somehow, please let me know how in the comments.


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