pip install flask-mongoengine

from flask import Flask
from flask.ext.mongoengine import MongoEngine
 
app = Flask(__name__)
app.config.from_pyfile('the-config.cfg')
db = MongoEngine(app)

Or, if you are setting up your database before your app is initialized….

from flask import Flask
from flask.ext.mongoengine import MongoEngine
db = MongoEngine()
...
app = Flask(__name__)
app.config.from_pyfile('the-config.cfg')
db.init_app(app)

app.config['MONGODB_SETTINGS'] = {
    'db': 'project1',
    'host': '192.168.1.35',
    'port': 12345,
    'username':'webapp',
    'password':'pwd123'
}

app.config['MONGODB_DB'] = 'project1'
app.config['MONGODB_HOST'] = '192.168.1.35'
app.config['MONGODB_PORT'] = 12345
app.config['MONGODB_USERNAME'] = 'webapp'
app.config['MONGODB_PASSWORD'] = 'pwd123'

Flask MongoEngine attaches methods to MongoEngine:

• get_or_404: works like .get(), but calls abort(404) if the object DoesNotExist.
• first_or_404: same as above, except for .first().
• paginate: paginates the QuerySet. Takes two arguments, page and per_page.
• paginate_field: paginates a field from one document in the QuerySet. Arguments: field_name, doc_id, page, per_page.

# 404 if object doesn't exist
def view_todo(todo_id):
    todo = Todo.objects.get_or_404(_id=todo_id)
..
 
# Paginate through todo
def view_todos(page=1):
    paginated_todos = Todo.objects.paginate(page=page, per_page=10)
 
# Paginate through tags of todo
def view_todo_tags(todo_id, page=1):
    todo = Todo.objects.get_or_404(_id=todo_id)
    paginated_tags = todo.paginate_field('tags', page, per_page=10)