[adbh] supported_backends is now defined in lgc (was defined in RQL before)

Each FunctionDescr can now declare on which DB it is supported

2 files changed, 57 insertions, 2 deletions

diff --git a/adbh.py b/adbh.py
index f496b1a..67259d6 100644
--- a/adbh.py
+++ b/adbh.py
@@ -31,6 +31,7 @@ class metafunc(type):
 class FunctionDescr(object):
     __metaclass__ = metafunc
 
+    supported_backends = ()
     rtype = None # None <-> returned type should be the same as the first argument
     aggregat = False
     minargs = 1
@@ -86,6 +87,7 @@ class _GenericAdvFuncHelper:
     """    
     # DBMS resources descriptors and accessors
     
+    backend_name = None # overriden in subclasses ('postgres', 'sqlite', etc.)
     needs_from_clause = False
     union_parentheses_support = True
     users_support = True
@@ -155,7 +157,7 @@ class _GenericAdvFuncHelper:
     def system_database(self):
         """return the system database for the given driver"""
         raise NotImplementedError('not supported by this DBMS')
-    
+
     def backup_command(self, dbname, dbhost, dbuser, dbpassword, backupfile,
                        keepownership=True):
         """return a command to backup the given database"""
@@ -276,6 +278,7 @@ def pgdbcmd(cmd, dbhost, dbuser):
 class _PGAdvFuncHelper(_GenericAdvFuncHelper):
     """Postgres helper, taking advantage of postgres SEQUENCE support
     """
+    backend_name = 'postgres'
     # modifiable but should not be shared
     FUNCTIONS = _GenericAdvFuncHelper.FUNCTIONS.copy()
     
@@ -386,6 +389,7 @@ class _SqliteAdvFuncHelper(_GenericAdvFuncHelper):
 
     An exception is raised when the functionality is not emulatable
     """
+    backend_name = 'sqlite'
     # modifiable but should not be shared
     FUNCTIONS = _GenericAdvFuncHelper.FUNCTIONS.copy()
     
@@ -411,6 +415,7 @@ class _SqliteAdvFuncHelper(_GenericAdvFuncHelper):
 class _MyAdvFuncHelper(_GenericAdvFuncHelper):
     """MySQL helper, taking advantage of postgres SEQUENCE support
     """
+    backend_name = 'mysql'
     needs_from_clause = True
     ilike_support = False # insensitive search by default
 
@@ -514,3 +519,9 @@ def get_adv_func_helper(driver):
 def register_function(driver, funcdef):
     ADV_FUNC_HELPER_DIRECTORY[driver].register_function(funcdef)    
 
+# this function should be called `register_function` but the other
+# definition was defined prior to this one
+def auto_register_function(funcdef):
+    """register the function `funcdef` on supported backends"""
+    for driver in  funcdef.supported_backends:
+        register_function(driver, funcdef)
diff --git a/test/unittest_db.py b/test/unittest_db.py
index de86afd..9610ae8 100644
--- a/test/unittest_db.py
+++ b/test/unittest_db.py
@@ -7,7 +7,10 @@ import socket
 from logilab.common.testlib import TestCase, unittest_main
 from logilab.common.db import *
 from logilab.common.db import PREFERED_DRIVERS
-from logilab.common.adbh import _SqliteAdvFuncHelper, _PGAdvFuncHelper
+from logilab.common.adbh import (_GenericAdvFuncHelper, _SqliteAdvFuncHelper,
+                                 _PGAdvFuncHelper, _MyAdvFuncHelper,
+                                 FunctionDescr, get_adv_func_helper,
+                                 auto_register_function)
 
 
 class PreferedDriverTC(TestCase):
@@ -132,6 +135,7 @@ class DBAPIAdaptersTC(TestCase):
     def setUp(self):
         """Memorize original PREFERED_DRIVERS"""
         self.old_drivers = PREFERED_DRIVERS['postgres'][:]
+        self.base_functions = dict(_GenericAdvFuncHelper.FUNCTIONS)
         self.host = 'crater.logilab.fr'
         self.db = 'gincotest2'
         self.user = 'adim'
@@ -140,6 +144,10 @@ class DBAPIAdaptersTC(TestCase):
     def tearDown(self):
         """Reset PREFERED_DRIVERS as it was"""
         PREFERED_DRIVERS['postgres'] = self.old_drivers
+        _GenericAdvFuncHelper.FUNCTIONS = self.base_functions
+        _PGAdvFuncHelper.FUNCTIONS = dict(self.base_functions)
+        _MyAdvFuncHelper.FUNCTIONS = dict(self.base_functions)
+        _SqliteAdvFuncHelper.FUNCTIONS = dict(self.base_functions)
 
     def test_raise(self):
         self.assertRaises(UnknownDriver, get_dbapi_compliant_module, 'pougloup')
@@ -185,5 +193,41 @@ class DBAPIAdaptersTC(TestCase):
         self.failUnless(isinstance(module.adv_func_helper, _SqliteAdvFuncHelper))
 
 
+    def test_auto_register_funcdef(self):
+        class RANDOM(FunctionDescr):
+            supported_backends = ('postgres', 'sqlite',)
+            rtype = 'Float'
+            minargs = maxargs = 0
+            name_mapping = {'postgres': 'RANDOM',
+                            'mysql': 'RAND',
+                            'sqlite': 'SQLITE_RANDOM'}
+        auto_register_function(RANDOM)
+
+        pghelper = get_adv_func_helper('postgres')
+        mshelper = get_adv_func_helper('mysql')
+        slhelper = get_adv_func_helper('sqlite')
+        self.failUnless('RANDOM' in pghelper.FUNCTIONS)
+        self.failUnless('RANDOM' in slhelper.FUNCTIONS)
+        self.failIf('RANDOM' in mshelper.FUNCTIONS)
+
+
+    def test_funcname_with_different_backend_names(self):
+        class RANDOM(FunctionDescr):
+            supported_backends = ('postgres', 'mysql', 'sqlite')
+            rtype = 'Float'
+            minargs = maxargs = 0
+            name_mapping = {'postgres': 'RANDOM',
+                            'mysql': 'RAND',
+                            'sqlite': 'SQLITE_RANDOM'}
+        auto_register_function(RANDOM)
+
+        pghelper = get_adv_func_helper('postgres')
+        mshelper = get_adv_func_helper('mysql')
+        slhelper = get_adv_func_helper('sqlite')
+        self.assertEquals(pghelper.func_sqlname('RANDOM'), 'RANDOM')
+        self.assertEquals(mshelper.func_sqlname('RANDOM'), 'RAND')
+        self.assertEquals(slhelper.func_sqlname('RANDOM'), 'SQLITE_RANDOM')
+            
+
 if __name__ == '__main__':
     unittest_main()