parse db name out of connection string

Author: timgraham

django_mongodb_backend/base.py

@@ -11,6 +11,7 @@
 from pymongo.collection import Collection
 from pymongo.driver_info import DriverInfo
 from pymongo.mongo_client import MongoClient
+from pymongo.uri_parser import parse_uri
 
 from . import __version__ as django_mongodb_backend_version
 from . import dbapi as Database
@@ -157,6 +158,18 @@ def __init__(self, settings_dict, alias=DEFAULT_DB_ALIAS):
         self.in_atomic_block_mongo = False
         # Current number of nested 'atomic' calls.
         self.nested_atomics = 0
+        # If "NAME" isn't specified, try to get the database name from HOST,
+        # if it's a connection string.
+        if self.settings_dict["NAME"] == "":  # Empty string = unspecified; None = _nodb_cursor()
+            name_is_missing = True
+            host = self.settings_dict["HOST"]
+            if host.startswith(("mongodb://", "mongodb+srv://")):
+                uri = parse_uri(host)
+                if database := uri.get("database"):
+                    self.settings_dict["NAME"] = database
+                    name_is_missing = False
+            if name_is_missing:
+                raise ImproperlyConfigured('settings.DATABASES is missing the "NAME" value.')
 
     def get_collection(self, name, **kwargs):
         collection = Collection(self.database, name, **kwargs)
@@ -183,8 +196,6 @@ def init_connection_state(self):
 
     def get_connection_params(self):
         settings_dict = self.settings_dict
-        if not settings_dict["NAME"]:
-            raise ImproperlyConfigured('settings.DATABASES is missing the "NAME" value.')
         params = {
             "host": settings_dict["HOST"] or None,
             **settings_dict["OPTIONS"],

tests/backend_/test_base.py

@@ -1,3 +1,5 @@
+from unittest.mock import patch
+
 from django.core.exceptions import ImproperlyConfigured
 from django.db import connection
 from django.db.backends.signals import connection_created
@@ -6,14 +8,47 @@
 from django_mongodb_backend.base import DatabaseWrapper
 
 
-class GetConnectionParamsTests(SimpleTestCase):
+class DatabaseWrapperTests(SimpleTestCase):
     def test_database_name_empty(self):
         settings = connection.settings_dict.copy()
         settings["NAME"] = ""
         msg = 'settings.DATABASES is missing the "NAME" value.'
         with self.assertRaisesMessage(ImproperlyConfigured, msg):
-            DatabaseWrapper(settings).get_connection_params()
+            DatabaseWrapper(settings)
+
+    def test_database_name_empty_and_host_does_not_contain_database(self):
+        settings = connection.settings_dict.copy()
+        settings["NAME"] = ""
+        settings["HOST"] = "mongodb://localhost"
+        msg = 'settings.DATABASES is missing the "NAME" value.'
+        with self.assertRaisesMessage(ImproperlyConfigured, msg):
+            DatabaseWrapper(settings)
+
+    def test_database_name_parsed_from_host(self):
+        settings = connection.settings_dict.copy()
+        settings["NAME"] = ""
+        settings["HOST"] = "mongodb://localhost/db"
+        self.assertEqual(DatabaseWrapper(settings).settings_dict["NAME"], "db")
 
+    def test_database_name_parsed_from_srv_host(self):
+        settings = connection.settings_dict.copy()
+        settings["NAME"] = ""
+        settings["HOST"] = "mongodb+srv://localhost/db"
+        # patch() prevents a crash when PyMongo attempts to resolve the
+        # nonexistent SRV record.
+        with patch("dns.resolver.resolve"):
+            self.assertEqual(DatabaseWrapper(settings).settings_dict["NAME"], "db")
+
+    def test_database_name_not_overridden_by_host(self):
+        settings = connection.settings_dict.copy()
+        settings["NAME"] = "should not be overridden"
+        settings["HOST"] = "mongodb://localhost/db"
+        self.assertEqual(
+            DatabaseWrapper(settings).settings_dict["NAME"], "should not be overridden"
+        )
+
+
+class GetConnectionParamsTests(SimpleTestCase):
     def test_host(self):
         settings = connection.settings_dict.copy()
         settings["HOST"] = "host"