Find_one, MongoDB. Often just a single match is needed in a MongoDB query. The find_one method is ideal here. It returns the values found, or None if nothing matches.
With None, we can test the database to ensure a document is not present. This helps us avoid conflicts. Find_one is easy to use once the MongoDB is ready.
An example. Consider this example program. We reset the "categories" collection in a "content" database. We add 3 documents, each with a language key.
And We set the status one each document as well. This can be retrieved from the result of find_one.
Detail We invoke find_one on the categories collection. One match for "Java" is returned.
from pymongo import MongoClient
client = MongoClient("mongodb://127.0.0.1:27017")
db = client.content
# Reset.
db.categories.delete_many({})
# Insert some documents.
db.categories.insert_many([
{"language": "C#", "status": 1},
{"language": "Java", "status": 1},
{"language": "Python", "status": 2},
])
# Find a matching document.
print("FIND ONE JAVA")
result = db.categories.find_one({"language": "Java"})
print(result)
# Access the status key.
print("STATUS")
print(result["status"])
# This query matches no documents.
print("FIND ONE FORTRAN")
result = db.categories.find_one({"language": "Fortran"})
print(result)
if result == None:
print("NOT FOUND")FIND ONE JAVA
{'status': 1, 'language': 'Java',
'_id': ObjectId('59efce1a25149714a00cf82d')}
STATUS
1
FIND ONE FORTRAN
None
NOT FOUND
Notes, None. Our database does not include an entry matching "Fortran." So the None value is returned. We can test None directly in Python.
A summary. With the return value of find_one, we can access individual keys and values (like in a Python dictionary). The syntax of MongoDB here is clear.
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