Allow setting of a user-specified external database. Fixes #1.

README

@@ -41,3 +41,9 @@ It is configured in the ``trac.ini`` file by enabling and configuring::
 
 The ``TRAC_ADMIN`` permission is used to control access to the query pages.
 
+By default, the TracSQL plugin connects to the project database.  To use an
+external database, set the ``database`` parameter in the ``tracsql`` section
+of the ``trac.ini`` file to a valid database connection string::
+
+    [tracsql]
+    database = sqlite:db/external.db

tracsql/web_ui.py

@@ -6,6 +6,7 @@
 # trac imports
 import trac
 from trac.core import *
+from trac.db.api import DatabaseManager
 from trac.util.html import html
 from trac.web import IRequestHandler
 from trac.web.chrome import INavigationContributor, ITemplateProvider
@@ -54,17 +55,33 @@ def match_request(self, req):
             req.args['path'] = path or '/'
             return True
 
+    def get_db_cnx(self):
+        """
+        Load the database, either user-specified or the project database.
+        """
+        db_str = self.env.config.get('tracsql', 'database', '')
+
+        if db_str:
+            class ExternalDatabaseManager(DatabaseManager):
+                connection_uri = db_str
+            db_mgr = ExternalDatabaseManager(self.env)
+            db = db_mgr.get_connection()
+
+        else:
+            db_str = self.env.config.get('trac', 'database')
+            db = self.env.get_db_cnx()
+
+        return db, db_str
+
     def process_request(self, req):
         req.perm.require('TRAC_ADMIN')
 
         path = req.args.get('path', '')
 
         data = {}
 
-        db = self.env.get_db_cnx()
+        db, db_str = self.get_db_cnx()
         cursor = db.cursor()
-
-        db_str = self.env.config.get('trac', 'database')
         db_type, db_path = db_str.split(':', 1)
         assert db_type in ('sqlite', 'mysql', 'postgres'), \
                             'Unsupported database "%s"' % db_type