How to view document fields in mongo shell?

Question

Is there a way to figure out the fields/keys in a document while in mongo\'s shell? As an example, let\'s say we have a document like (pseudocode):

{
    \"m         


        

Answer 1

To get a list of all fields used in a collection in MongoDB, this is the way I found most straightforward (your mileage may vary :) ):

Create a .js file with the content:

use yourdbname
mr = db.runCommand({
  "mapreduce" : "collectionName",
  "map" : function() {
    for (var key in this) { emit(key, null); }
  },
  "reduce" : function(key, stuff) { return null; },
  "out": "collectionName" + "_keys"
})
db[mr.result].distinct("_id")

I found out how to do this here (GeoffTech blog)

I ran it from the shell to print the output in the console

mongo < nameOfYourFile.js 

or dump the output in a text file:

mongo < nameOfYourFile.js > outputDir\nameOfYourOutputFile.txt

I'm totally new to MongoDb so I hope it does indeed get all fields regardless of use throughout the documents!

(I'm using MongoDb on windows 10, so my console may differ from yours)