The MongoDB Database Tools include a utility called mongoexport that enables you to export MongoDB data to a CSV or JSON file.

One of the things you can do with this utitlity is export query results. This article shows you how to use mongoexport to export MongoDB query results to a CSV file.

Syntax

The syntax for mongoexport goes like this:

mongoexport --collection=<coll> <options> <connection-string>

You need to run mongoexport commands from your system’s command line (e.g. a new Terminal or Command Prompt window).

Don’t run mongoexport commands from the mongo shell.

Example

The following example code exports the results of a query to a CSV file:

mongoexport --db=PetHotel --collection=pets --type=csv --fields=_id,name,type,weight --query='{ "type": "Dog" }' --out=data/dogs.csv

This exports a query that queries a collection called pets in the PetHotel database. The query is exported to a file called dogs.csv in the data/ folder.

If the folder doesn’t exist, it’s created. Same with the file. By the way, this assumes that there are no permission issues with writing a file to the specified location.

In this example I didn’t specify any host, port, authentication, etc, so it exports the collection from the MongoDB instance running on the default localhost port number 27017.

Below is an explanation of the parameters we supplied here.

Parameter	Description
--db or -d	Specifies the database on which to run mongoexport. In this case, the database is called PetHotel. This parameter can alternatively be passed using -d (instead of --db).
--collection or -c	Specifies the collection we want to export (or run the query against). In this case, the collection is called pets. This parameter can alternatively be passed as -c (instead of --collection).
--type	Specifies the exported file type. In this case we specify csv to export it to a CSV file.
--fields	Specifies the fields that we want to export. We have the option of exporting all fields or just some. You need to list each one here, separated by a comma. When exporting to CSV, specifying the field names is a requirement. You can do so via the --fields parameter or the --fieldFile parameter (more on that later).
--query or -q	Specifies the query for which results we want to export. This must be enclosed in single quotes (so that it doesn’t interact with your shell). This parameter can also be passed using -q.
--out	Specifies the exported file name and where it will be located. If you don’t specify a file name, mongoexport writes data to standard output (stdout).

Check the Exported File

Let’s verify that the export operation worked as expected.

First, let’s run the query against the original collection.

use PetHotel
db.pets.find({ "type": "Dog" })

Result:

{ "_id" : 1, "name" : "Wag", "type" : "Dog", "weight" : 20 }
{ "_id" : 2, "name" : "Bark", "type" : "Dog", "weight" : 10 }
{ "_id" : 6, "name" : "Fetch", "type" : "Dog", "weight" : 17 }
{ "_id" : 7, "name" : "Jake", "type" : "Dog", "weight" : 30 }

So we can see that there are 4 dogs, all with the same fields that we specified in our export operation.

Now let’s open up the exported file dogs.csv to see what’s inside:

_id,name,type,weight
1,Wag,Dog,20
2,Bark,Dog,10
6,Fetch,Dog,17
7,Jake,Dog,30

OK, so all data is in the exported file as expected.

Export Less Fields

You can specify less fields with the --fields parameter if you wish.

Example:

mongoexport --db=PetHotel --collection=pets --type=csv --fields=name,weight --query='{ "type": "Dog" }' --out=data/dogs.csv

Resulting file:

name,weight
Wag,20
Bark,10
Fetch,17
Jake,30

Remove Column Headers

You’ll notice that the exported file in the previous examples included the column headers.

You also have the option of exporting the file without column headers. To do this, use the --noHeaderLine parameter.

Example:

mongoexport --db=PetHotel --collection=pets --type=csv --fields=_id,name,type,weight --query='{ "type": "Dog" }' --noHeaderLine --out=data/dogs.csv

Now when I open up the exported file, there are no column headers:

1,Wag,Dog,20
2,Bark,Dog,10
6,Fetch,Dog,17
7,Jake,Dog,30

Use a File for the Field Names

You can replace the --field parameter with the --fieldFile parameter to specify the name of a file that contains the field names that you want to export.

mongoexport --db=PetHotel --collection=pets --type=csv --fieldFile=data/dogs_fields.txt --query='{ "type": "Dog" }' --out=data/dogs.csv

The file that contains the fields must have the fields listed, one per line.

Here’s what the dogs_fields.txt file looked like for this example:

name
type
weight

This resulted in the contents of the exported file looking like this:

name,type,weight
Wag,Dog,20
Bark,Dog,10
Fetch,Dog,17
Jake,Dog,30

Changing the Column Order

You can switch the ordering of the fields to export. They don’t have to be in the same order as the underlying document.

For example, this code:

mongoexport --db=PetHotel --collection=pets --type=csv --fields=type,name,weight,_id --query='{ "type": "Dog" }' --out=data/dogs.csv

Results in the following CSV file:

type,name,weight,_id
Dog,Wag,20,1
Dog,Bark,10,2
Dog,Fetch,17,6
Dog,Jake,30,7

Access Control/Authentication

If you’re not using localhost, you can use the --host parameter to specify the host, and --port to specify the port. You can also use the --username parameter to specify the user name and --password to for the password. If you omit the password parameter, you will be prompted for it. There’s also an --authenticationDatabase parameter for specifying the authentication database where the user has been created.

Example:

mongoexport --host=myhost.example.com --port=37017 --username=homer --authenticationDatabase=admin --db=PetHotel --collection=pets --type=csv --fields=_id,name,type,weight --query='{ "type": "Dog" }' --out=data/dogs.csv

Check for mongoexport

mongoexport is part of the MongoDB Database Tools package. The MongoDB Database Tools are a suite of command-line utilities for working with MongoDB.

If you’re not sure whether you have the MongoDB Database Tools/mongoexport installed, try running the following command in your Terminal or Command Prompt to check:

mongoexport --version

If you have it, you should see version information, etc. If you don’t have it, you can use the installation instructions over at the MongoDB website to install it on to your system.

Where to Run the Commands?

Don’t forget, you need to run mongoexport commands from your system’s command line (e.g. a new Terminal or Command Prompt window).