A comparison between marrow.mongo query structuring results and other ODMs.

_marrow_mongo.py

from marrow.mongo import Document, F
from marrow.mongo.field import Array, Number, String

# 2016? Yikes! Hello from 2019! Imports updated, missing REPRs added.

class Person(Document):
	name = String()
	age = Number()
	tag = Array(String())


Person.name == "Alice"
# Op({'name': 'Alice'})

Person.age >= 21
# Op({'age': {'$gte': 21}})

query = (Person.name == "Alice") & (Person.age >= 21) & Person.tag.any(["foo", "bar"])
# query = Ops({'name': 'Alice', 'tag': {'$in': ['foo', 'bar']}, 'age': {'$gte': 21}})

query = a.as_query  # We now have the above MongoDB query by itself.
# query = {'name': 'Alice', 'tag': {'$in': ['foo', 'bar']}, 'age': {'$gte': 21}}

Ops(query) & (Document.age < 65)  # And can re-bundle and update it!
# Ops({'name': 'Alice', 'tag': {'$in': ['foo', 'bar']}, 'age': {'$gte': 21, '$lt': 65}})

query = (Person.name == "Alice") & (Person.age >= 21) | Person.tag.any(["foo", "bar"])
# query = Filter([('$or', [
# 	{'name': 'Alice', 'age': {'$gte': 21}},
#	{'tag': {'$in': ['foo', 'bar']}}
# ])])

# A little Django-ish querying can save smoe space, but can't do "or" conditions itself.
query = F(Person, name="Alice", age__ge=21) | Person.tag.any(["foo", "bar"])
# query = Filter([('$or', [
#	OrderedDict([('name', 'Alice'), ('age', {'$gte': 21})
# ]), {'tag': {'$in': ['foo', 'bar']}}])])

mongoengine_.py

from mongoengine import Document, StringField, IntField, ListField

class Person(Document):
	name = StringField()
	age = NumberField()
	tag = ListField(StringField())


Q(name="Alice")
# <mongoengine.queryset.visitor.Q at 0x1059f9e80>
# Okay, the __repr__ is useless.  :|

Q(name="Alice").to_query(Person)
# {'name': 'Alice'}
# Success!  It absolutely requires concrete tanslation.

Q(age__gte=21).to_query(Person)
# {'age': {'$gte': 21}}
# No surprises here.

query = Q(name="Alice") & Q(age__gte=21) & Q(tag__in=("foo", "bar"))
# query = <mongoengine.queryset.visitor.QCombination at 0x105c96e48>
# Right.  

badquery = query.to_query(Person)
# badquery = {'age': {'$gte': 21}, 'name': 'Alice', 'tag': {'$in': ['foo', 'bar']}}
# Now we have the raw, full query.

# Can't re-form from MongoDB version.  :|

query = query & Q(age < 65)

query.to_query(Person)
# {'age': {'$gte': 21, '$lt': 65}, 'name': 'Alice', 'tag': {'$in': ['foo', 'bar']}}

query = Q(name="Alice") & Q(age__gte=21) | Q(tag__in=("foo", "bar"))
query.to_query(Person)
# {'$or': [
#	{'age': {'$gte': 21}, 'name': 'Alice'},
#	{'tag': {'$in': ['foo', 'bar']}}
# ]}

(query & Q(age__lt=65)).to_query(Person)
# {'$and': [{'$or': [{'age': {'$gte': 21}, 'name': 'Alice'},
#    {'tag': {'$in': ['foo', 'bar']}}]},
#  {'age': {'$lt': 65}}]}