MacLochlainns Weblog

There are many ways to test and edit files. A lot of developers only use their favorite Integrated Developer Environment (IDE) but I find testing script files within the scope of a pipelined set of scripts much faster.

The ability to edit a JavaScript file from within the mongo Shell would be nice but unfortunately, it doesn’t exist. You are able to edit a complex variable with a mechanism quite like the Oracle Database. Rather than leave you hanging on how to edit a complex variable in the mongo shell, here are the steps before launching into how to test your JavaScript files:

1. You can enter this manually during any connection to the mongo shell or put it in your .mongorc.js configuration file, like this in Fedora with the fully qualified filename:

   EDITOR="/usr/bin/vim"

   EDITOR="/usr/bin/vim"

2. Let’s say you have a stooges array variable that contains “Moe”, “Curly”, and “Larry” and you want to add “Shemp” to the variable. You can edit the stooges array variable with vi and add “Shemp” to it by typing edit and the stooges variable name.

   edit stooges

   edit stooges

3. Then, you can test the stooges array variable’s new values:

   stooges

   stooges

4. It returns the following:

   [ "Moe", "Curly", "Shemp", "Larry" ]

   [ "Moe", "Curly", "Shemp", "Larry" ]

Unfortunately, these changes to the demo array variable will be lost after you break the connection. While it does afford a quick test case, you should make the changes in the external JavaScript file. Then, the change is there the the next time you access the resource file.

Here’s my quick edit and test script technique for MongoDB from your present working directory:

1. Assume you create a compliment.js test file, like:

   /* Declare an array variable and random index value. */ var compliment = ["Bashful","Doc","Dopey","Grumpy","Happy","Sleepy","Sneezy"] var index = Math.floor(Math.random()*7)   /* Print a welcome message. */ print("Hello, " + compliment[index] + ".")

   /* Declare an array variable and random index value. */ var compliment = ["Bashful","Doc","Dopey","Grumpy","Happy","Sleepy","Sneezy"] var index = Math.floor(Math.random()*7) /* Print a welcome message. */ print("Hello, " + compliment[index] + ".")

2. You can edit the compliment.js file with vi and test the script interactively from the present working directory.
   • You can edit the file with the following syntax:

     vi compliment.js

     vi compliment.js

   • then, you can test the task.sql file:

     mongo --nodb --norc < compliment.js

     mongo --nodb --norc < compliment.js

   • The --nodb option instructs MongoDB to not connect to a database and the --norc option instructs MongoDB to not load your .mongorc.js file. Effectively, disabling the database connection and loading of the MongoDB resource file (.mongorc.js) lets you test your code in MongoDB’s Javascript shell unencumbered by any overhead from the MongoDB server.

     The foregoing script returns the following:

     MongoDB shell version v4.0.19 Hello, Sneezy. bye

     MongoDB shell version v4.0.19 Hello, Sneezy. bye

   • If you have the desired outcome, you’re done. However, if you need further change you repeat the process.

As always, I hope this helps those looking for a quick way to accomplish a task.