Introduction to MongoDB cursor.isExhausted() Method

cursor.isExhausted() is a cursor method in MongoDB that is used to determine whether the cursor has been fully traversed. When the cursor has been fully traversed, the method returns True, otherwise it returns False.

Syntax

db.collection.find().isExhausted()

Use Case

When querying documents in MongoDB using a cursor, it is often necessary to determine whether the cursor has been fully traversed. In such cases, the cursor.isExhausted() method can be used to determine whether the cursor has been fully traversed, so that the cursor can be closed in a timely manner to avoid wasting resources.

Example

Assuming there is a collection called users in MongoDB that contains multiple documents, each document containing two fields: name and age. Now suppose we need to traverse all the documents in the collection and output the documents whose age is greater than or equal to 18 to the console.

from pymongo import MongoClient

# Connect to the MongoDB database
client = MongoClient('mongodb://localhost:27017/')

# Get the collection named 'users'
collection = client['test']['users']

# Define the query condition, query all documents with an age greater than or equal to 18
query = {'age': {'$gte': 18}}

# Get the cursor
cursor = collection.find(query)

# Traverse the cursor and output the documents with an age greater than or equal to 18
for doc in cursor:
    print(doc)

    # Determine whether the cursor has been fully traversed
    if cursor.isExhausted():
        print('The cursor has been fully traversed')
        break

# Close the cursor
cursor.close()

# Close the MongoDB connection
client.close()

After running the above code, the program will traverse all the documents with an age greater than or equal to 18 in the users collection and output them to the console. After the traversal is complete, the program will close the cursor and output “The cursor has been fully traversed”.

Conclusion

cursor.isExhausted() is a cursor method in MongoDB that is used to determine whether the cursor has been fully traversed. When the cursor has been fully traversed, the method returns True, otherwise it returns False. When performing a cursor query, this method can be used to determine whether the cursor has been fully traversed, so that the cursor can be closed in a timely manner to avoid wasting resources.