Make sure PostGIS is >= 1.5

Raise an AssertionError when postgis is not >= 1.5.

ocitysmap2.conf-template

@@ -0,0 +1,22 @@
+[datasource]
+host=localhost
+user=maposmatic
+password=mysecurepasswd
+dbname=maposmatic
+
+[rendering]
+# List of available stylesheets, each needs to be described by an eponymous
+# configuration section in this file.
+available_stylesheets: stylesheet_osm1, stylesheet_osm2
+
+# The default Mapnik stylesheet.
+[stylesheet_osm1]
+name: Default
+description: The default OSM style
+path: /path/to/mapnik-osm/osm.xml
+
+# Another stylesheet
+[stylesheet_osm2]
+name: AnotherOne
+description: Another OSM Stylesheet
+path: /path/to/another/osm.xml

ocitysmap2/__init__.py

@@ -244,6 +244,9 @@ class OCitySMap:
         # (which loads the unicode extensions for psycopg2)
         db.set_client_encoding('utf8')
 
+        # Make sure the DB is correctly installed
+        self._verify_db(db)
+
         try:
             timeout = int(self._parser.get('datasource', 'request_timeout'))
         except (ConfigParser.NoOptionError, ValueError):
@@ -253,6 +256,18 @@ class OCitySMap:
         self.__db = db
         return self.__db
 
+    def _verify_db(self, db):
+        """Make sure the PostGIS DB is compatible with us."""
+        cursor = db.cursor()
+        cursor.execute("""
+SELECT ST_AsText(ST_LongestLine(
+                    'POINT(100 100)'::geometry,
+		    'LINESTRING(20 80, 98 190, 110 180, 50 75 )'::geometry)
+	        ) As lline;
+""")
+        assert cursor.fetchall()[0][0] == "LINESTRING(100 100,98 190)", \
+            LOG.fatal("PostGIS >= 1.5 required for correct operation !")
+
     def _set_request_timeout(self, db, timeout_minutes=15):
         """Sets the PostgreSQL request timeout to avoid long-running queries on
         the database."""