db_alias support and fixes for custom map/reduce output

mongoengine/queryset/base.py

@@ -7,12 +7,14 @@ import pprint
 import re
 import warnings
 
+from bson import SON
 from bson.code import Code
 from bson import json_util
 import pymongo
 from pymongo.common import validate_read_preference
 
 from mongoengine import signals
+from mongoengine.connection import get_db
 from mongoengine.common import _import_class
 from mongoengine.base.common import get_document
 from mongoengine.errors import (OperationError, NotUniqueError,
@@ -923,7 +925,36 @@ class BaseQuerySet(object):
             map_reduce_function = 'inline_map_reduce'
         else:
             map_reduce_function = 'map_reduce'
-            mr_args['out'] = output
+
+            if isinstance(output, basestring):
+                mr_args['out'] = output
+                
+            elif isinstance(output, dict):
+                ordered_output = []
+
+                for part in ('replace', 'merge', 'reduce'):
+                    value = output.get(part)
+                    if value:
+                        ordered_output.append((part, value))
+                        break
+                
+                else:
+                    raise OperationError("actionData not specified for output")
+
+                db_alias = output.get('db_alias')
+                remaing_args = ['db', 'sharded', 'nonAtomic']
+                
+                if db_alias:
+                    ordered_output.append(('db', get_db(db_alias).name))
+                    del remaing_args[0]
+
+                
+                for part in remaing_args:
+                    value = output.get(part)
+                    if value:
+                        ordered_output.append((part, value))
+                
+                mr_args['out'] = SON(ordered_output)
 
         results = getattr(queryset._collection, map_reduce_function)(
                           map_f, reduce_f, **mr_args)

tests/queryset/queryset.py

@@ -14,7 +14,7 @@ from pymongo.read_preferences import ReadPreference
 from bson import ObjectId
 
 from mongoengine import *
-from mongoengine.connection import get_connection
+from mongoengine.connection import get_connection, get_db
 from mongoengine.python_support import PY3
 from mongoengine.context_managers import query_counter
 from mongoengine.queryset import (QuerySet, QuerySetManager,
@@ -1925,6 +1925,140 @@ class QuerySetTest(unittest.TestCase):
 
         BlogPost.drop_collection()
 
+    def test_map_reduce_custom_output(self):
+        """
+        Test map/reduce custom output
+        """
+        register_connection('test2', 'mongoenginetest2')
+        
+        class Family(Document):
+            id = IntField(
+                primary_key=True)
+            log = StringField()
+
+        class Person(Document):
+            id = IntField(
+                primary_key=True)
+            name = StringField()
+            age = IntField()
+            family = ReferenceField(Family)
+            
+        Family.drop_collection()
+        Person.drop_collection()
+        
+        # creating first family
+        f1 = Family(id=1, log="Trav 02 de Julho")
+        f1.save()
+
+        # persons of first family
+        Person(id=1, family=f1, name=u"Wilson Jr", age=21).save()
+        Person(id=2, family=f1, name=u"Wilson Father", age=45).save()
+        Person(id=3, family=f1, name=u"Eliana Costa", age=40).save()
+        Person(id=4, family=f1, name=u"Tayza Mariana", age=17).save()
+
+        # creating second family
+        f2 = Family(id=2, log="Av prof frasc brunno")
+        f2.save()
+
+        #persons of second family
+        Person(id=5, family=f2, name="Isabella Luanna", age=16).save()
+        Person(id=6, family=f2, name="Sandra Mara", age=36).save()
+        Person(id=7, family=f2, name="Igor Gabriel", age=10).save()
+        
+        # creating third family
+        f3 = Family(id=3, log="Av brazil")
+        f3.save()
+
+        #persons of thrird family
+        Person(id=8, family=f3, name="Arthur WA", age=30).save()
+        Person(id=9, family=f3, name="Paula Leonel", age=25).save()
+
+        # executing join map/reduce
+        map_person = """
+            function () {
+                emit(this.family, {
+                     totalAge: this.age,
+                     persons: [{
+                        name: this.name,
+                        age: this.age
+                }]});
+            }
+        """
+
+        map_family = """
+            function () {
+                emit(this._id, {
+                   totalAge: 0,
+                   persons: []
+                });
+            }
+        """
+
+        reduce_f = """
+            function (key, values) {
+                var family = {persons: [], totalAge: 0};
+    
+                values.forEach(function(value) {
+                    if (value.persons) {
+                        value.persons.forEach(function (person) {
+                            family.persons.push(person);
+                            family.totalAge += person.age;
+                        });
+                    }
+                });
+
+                return family;
+            }
+        """
+        cursor = Family.objects.map_reduce(
+            map_f=map_family,
+            reduce_f=reduce_f,
+            output={'replace': 'family_map', 'db_alias': 'test2'})
+
+        # start a map/reduce
+        cursor.next()
+
+        results = Person.objects.map_reduce(
+            map_f=map_person,
+            reduce_f=reduce_f,
+            output={'reduce': 'family_map', 'db_alias': 'test2'})
+
+        results = list(results)
+        collection = get_db('test2').family_map
+        
+        self.assertEqual(
+            collection.find_one({'_id': 1}), {
+                '_id': 1,
+                'value': {
+                    'persons': [
+                        {'age': 21, 'name': u'Wilson Jr'},
+                        {'age': 45, 'name': u'Wilson Father'},
+                        {'age': 40, 'name': u'Eliana Costa'},
+                        {'age': 17, 'name': u'Tayza Mariana'}],
+                    'totalAge': 123}
+                })
+
+        self.assertEqual(
+            collection.find_one({'_id': 2}), {
+                '_id': 2,
+                'value': {
+                    'persons': [
+                        {'age': 16, 'name': u'Isabella Luanna'},
+                        {'age': 36, 'name': u'Sandra Mara'},
+                        {'age': 10, 'name': u'Igor Gabriel'}],
+                    'totalAge': 62}
+                })
+
+        self.assertEqual(
+            collection.find_one({'_id': 3}), {
+                '_id': 3,
+                'value': {
+                    'persons': [
+                        {'age': 30, 'name': u'Arthur WA'},
+                        {'age': 25, 'name': u'Paula Leonel'}],
+                    'totalAge': 55}
+                })
+        
     def test_map_reduce_finalize(self):
         """Ensure that map, reduce, and finalize run and introduce "scope"
         by simulating "hotness" ranking with Reddit algorithm.