Mongo Shell - Console/Debug Log

🐢🔍 Mongo Shell - Console/Debug Log

So you're experimenting with the Mongo shell and want to output some information to the console while evaluating JavaScript functions? No worries, it's not a dumb question at all! In this blog post, we'll address this common issue and provide you with easy solutions to help you debug like a pro. 🤓

The Problem

Let's take a look at the code snippet you shared:

matt@linuxvm:~/mongodb-linux-i686-1.2.3/bin$ ./mongo
MongoDB shell version: 1.2.3
url: test
connecting to: test
Thu Feb 25 20:57:47 connection accepted from 127.0.0.1:37987 #3
type "help" for help
> function test() { debug.log("hello") }
> test()
Thu Feb 25 20:58:06 JS Error: ReferenceError: debug is not defined (shell):0

As you can see, when you try to use debug.log("hello") within the Mongo shell, it throws a ReferenceError. This means that the debug object or function is not recognized within the Mongo shell environment. 😱

The Solution

Fear not, there are other ways to achieve what you're looking for! Here are a couple of easy alternatives:

Solution 1: Use `print()`

One way to output information to the console while evaluating JavaScript functions in the Mongo shell is by using the print() function. It's a built-in function that does exactly what you need. Let's take a look at an example:

> function test() { print("hello") }
> test()
hello

Voila! The "hello" message will be printed in the console when you run the test() function.

Solution 2: Use `printjson()`

If you want to output more complex data structures like objects or arrays, you can use the printjson() function. It's similar to print(), but it's specifically designed to beautifully format JSON-like outputs. Check out this example:

> var data = { name: "John", age: 28 }
> function test() { printjson(data) }
> test()
{
  "name" : "John",
  "age" : 28
}

Awesome, right? Now you can output nicely formatted JSON-like outputs to the console!

Your Turn!

Now that you have a couple of easy solutions to output information to the console in the Mongo shell, it's time to get your hands dirty and try them out. Go ahead and experiment with the print() or printjson() functions in your admin or populate scripts. 🛠️

Share your experience with us! Did these solutions work for you? Do you have any other cool tips or tricks in the Mongo shell? We'd love to hear your thoughts and engage with the community. Drop a comment below and let's start a conversation! 🗣️💬

Happy coding! 😄🚀

Mongo Shell - Console/Debug Log