This MongoDB Get Started lesson is for a beginner. Read the short notes, run each example, then change one name or number and run it again.
MongoDB stores documents, which are objects of keys and values. A collection is a group of those documents.
This runner has no MongoDB server. A list of dicts stands in for a collection.
Example 1: Start here
A local client connects with a URI. Keep that URI out of the source file.
collection = [{"name": "Meera", "track": "Python"}] # a list; the values stay in this order
print(collection[0]["track"])
Example 2: Filter the rows
MongoDB Get Started is easier to see as a list of records. The filter keeps every row whose seats value is at least 10.
rows = [{"topic": "MongoDB Get Started", "seats": 11}, {"topic": "SQL", "seats": 12}] # a list; the values stay in this order
print([row["topic"] for row in rows if row["seats"] >= 10]) # keep the items that pass the test
Example 3: Update one field
An update changes one field and leaves the rest of the record alone. On a database you would run an UPDATE or an update_one for the same change.
row = {"topic": "MongoDB Get Started", "seats": 11} # a dictionary; each key has one value
row["seats"] = row["seats"] + 1 # change this one field
print(row)
Example 4: Count the matches
Counting matches is the idea behind COUNT(*). Here the number 11 appears twice.
rows = [11, 4, 11] # a list; the values stay in this order
print(sum(1 for value in rows if value == 11)) # keep the items that pass the test
A local client connects with a URI. Keep that URI out of the source file.
