As of mongoimport version 100.0.0, you can delete documents in MongoDB based on an imported file. To do this, use delete mode.

When you use delete mode, if an imported document has the same _id value as an existing one in the collection that you’re importing into, the existing document will be deleted.

You can also specify another field or fields (other than the _id field) to be the matching field if required.

Example

Suppose we have a collection called pets that contain the following documents:

db.pets.find()

Result:

{ "_id" : 1, "name" : "Wag", "type" : "Dog", "weight" : 20 }
{ "_id" : 2, "name" : "Bark", "type" : "Dog", "weight" : 10 }
{ "_id" : 3, "name" : "Meow", "type" : "Cat", "weight" : 7 }
{ "_id" : 4, "name" : "Scratch", "type" : "Cat", "weight" : 8 }
{ "_id" : 5, "name" : "Bruce", "type" : "Bat", "weight" : 3 }

And we have the following JSON file called pets.json:

{"_id":1,"name":"Wag","type":"Dog"}
{"_id":2,"name":"Fluffy","type":"Cat","weight":10}
{"_id":9,"name":"Hop","type":"Kangaroo","weight":60}

The following command imports the JSON file using delete mode:

mongoimport --db=PetHotel --collection=pets --mode=delete --file=data/pets.json

Running this command deletes any matching documents in the collection.

Check the Results

Let’s take a look at the collection now.

db.pets.find()

Result:

{ "_id" : 3, "name" : "Meow", "type" : "Cat", "weight" : 7 }
{ "_id" : 4, "name" : "Scratch", "type" : "Cat", "weight" : 8 }
{ "_id" : 5, "name" : "Bruce", "type" : "Bat", "weight" : 3 }

We can see that the first 2 documents have been deleted. They were deleted because their _id values matched the _id values in the existing documents. This is despite other details not necessarily matching (such as with document 2).

Also, our imported file had a document with an _id of 9 but there was no matching document, and so nothing was deleted for that one.

Change the Upsert Field/s

You can use the --upsertFields parameter to specify a field other than _id for which to match against. When using multiple fields with this parameter, pass them as a comma separated list.

Suppose we have another JSON file called pets2.json and it looks like this:

{ "name" : "Meow", "type" : "Cat", "weight" : 7 }
{ "name" : "Bubbles", "type" : "Fish", "weight" : 3 }

This document doesn’t include the _id field, so we would need to match against other fields that uniquely identify each document. In this case we could use the name and type fields.

We can therefore use the following mongoimport command:

mongoimport --db=PetHotel --collection=pets --mode=delete --upsertFields=name,type --file=data/pets2.json

Now let’s check the collection again:

db.pets.find()

Result:

{ "_id" : 4, "name" : "Scratch", "type" : "Cat", "weight" : 8 }
{ "_id" : 5, "name" : "Bruce", "type" : "Bat", "weight" : 3 }

Meow the cat was deleted because that pet existed in both the MongoDB collection and the imported document.

Bubbles the fish had no matching document and so nothing was deleted for that one.

Check for mongoimport

mongoimport 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/mongoimport installed, try running the following command in your Terminal or Command Prompt to check:

mongoimport --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 mongoimport commands from your system’s command line (e.g. a new Terminal or Command Prompt window).

Don’t run them from the mongo shell.