Get Collection Names of Database - PyMongo - Examples

List Collection Names of MongoDB Database

To list collection names present in a MongoDB database, follow these steps:

  1. Create a client to the MongoDB instance.
  2. Select a database from the client. This returns a reference to the database.
  3. Call the function list_collection_names() on the database reference.
  4. The function returns an iterator. Use a for loop to iterate through the list of collections.

Examples

1. Get List of MongoDB Collections

The following Python program lists the collection names present in a MongoDB database.

Python Program

import pymongo

myclient = pymongo.MongoClient("mongodb://localhost:27017/")

# Use database "organisation"
mydb = myclient['organisation']

print("List of collections\n--------------------")
# List the collections
for coll in mydb.list_collection_names():
    print(coll)

Explanation:

  1. We import the pymongo library and establish a connection to the local MongoDB instance using MongoClient.
  2. We select the organisation database using myclient['organisation'].
  3. We call list_collection_names() on the selected database reference mydb to retrieve the list of collections.
  4. The function returns an iterator, which we loop over using a for loop and print each collection name.

Output:

PyMongo List Collection Names in Database

2. Get Collection Names in a Remote MongoDB Instance

In this example, we connect to a remote MongoDB instance and list the collections from a database.

Python Program

import pymongo

myclient = pymongo.MongoClient("mongodb://remote_host:27017/")

# Use database "company"
mydb = myclient['company']

print("List of collections in 'company' database\n----------------------------------")
# List the collections
for coll in mydb.list_collection_names():
    print(coll)

Explanation:

  1. We connect to a remote MongoDB instance by providing the host URL mongodb://remote_host:27017/.
  2. We select the company database from the remote instance using myclient['company'].
  3. We then call list_collection_names() on the company database and print the collection names in that database.

3. Handle Empty Databases or Databases with No Collections

In some cases, a database might not have any collections. Here's an example to handle such cases gracefully.

Python Program

import pymongo

myclient = pymongo.MongoClient("mongodb://localhost:27017/")

# Use an empty database "emptyDB"
mydb = myclient['emptyDB']

# List collections, check if any exist
collections = mydb.list_collection_names()
if collections:
    print("Collections in 'emptyDB':", collections)
else:
    print("No collections found in 'emptyDB'.")

Explanation:

  1. We select a database named emptyDB which has no collections.
  2. We use list_collection_names() to get the list of collections, and then check if any collections exist.
  3. If the list is empty, we print a message indicating no collections were found.

Output:

No collections found in 'emptyDB'.

Summary

In this PyMongo Tutorial, we learned how to get the list of collections in a MongoDB database using list_collection_names() function, with examples demonstrating:

  • Listing collection names in a local MongoDB database.
  • Listing collections in a remote MongoDB instance.
  • Handling empty databases with no collections.

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