code reorg: create new utility method loadModel for db diffing

migrate/versioning/schema.py

@@ -1,6 +1,7 @@
 from sqlalchemy import Table,Column,MetaData,String,Integer,create_engine
 from sqlalchemy import exceptions as sa_exceptions
 from migrate.versioning.repository import Repository
+from migrate.versioning.util import loadModel
 from migrate.versioning.version import VerNum
 from migrate.versioning import exceptions, genmodel, schemadiff
 
@@ -98,12 +99,7 @@ class ControlledSchema(object):
 
         if isinstance(repository, basestring):
             repository=Repository(repository)
-        if isinstance(model, basestring):  # TODO: centralize this code?
+        model = loadModel(model)
-            # Assume model is of form "mod1.mod2.varname".
-            varname = model.split('.')[-1]
-            modules = '.'.join(model.split('.')[:-1])
-            module = __import__(modules, globals(), {}, ['dummy-not-used'], -1)
-            model = getattr(module, varname)
         diff = schemadiff.getDiffOfModelAgainstDatabase(model, engine, excludeTables=[repository.version_table])
         return diff
 
@@ -122,12 +118,7 @@ class ControlledSchema(object):
 
         if isinstance(repository, basestring):
             repository=Repository(repository)
-        if isinstance(model, basestring):  # TODO: centralize this code?
+        model = loadModel(model)
-            # Assume model is of form "mod1.mod2.varname".
-            varname = model.split('.')[-1]
-            modules = '.'.join(model.split('.')[:-1])
-            module = __import__(modules, globals(), {}, ['dummy-not-used'], -1)
-            model = getattr(module, varname)
         diff = schemadiff.getDiffOfModelAgainstDatabase(model, engine, excludeTables=[repository.version_table])
         return genmodel.ModelGenerator(diff).applyModel()
 

migrate/versioning/script/py.py

@@ -4,7 +4,7 @@ from migrate.versioning import exceptions, genmodel, schemadiff
 from migrate.versioning.base import operations
 from migrate.versioning.template import template
 from migrate.versioning.script import base
-from migrate.versioning.util import import_path
+from migrate.versioning.util import import_path, loadModel
 
 class PythonScript(base.BaseScript):
     @classmethod
@@ -28,12 +28,7 @@ class PythonScript(base.BaseScript):
         if isinstance(repository, basestring):
             from migrate.versioning.repository import Repository  # oh dear, an import cycle!
             repository=Repository(repository)
-        if isinstance(model, basestring):  # TODO: centralize this code?
+        model = loadModel(model)
-            # Assume model is of form "mod1.mod2.varname".
-            varname = model.split('.')[-1]
-            modules = '.'.join(model.split('.')[:-1])
-            module = __import__(modules, globals(), {}, ['dummy-not-used'], -1)
-            model = getattr(module, varname)
         diff = schemadiff.getDiffOfModelAgainstDatabase(model, engine, excludeTables=[repository.version_table])
         upgradeDecls, upgradeCommands = genmodel.ModelGenerator(diff).toUpgradePython()
         #downgradeCommands = genmodel.ModelGenerator(diff).toDowngradePython()

migrate/versioning/util/__init__.py

@@ -1,3 +1,14 @@
 from keyedinstance import KeyedInstance
 from importpath import import_path
 
+def loadModel(model):
+    ''' Import module and use module-level variable -- assume model is of form "mod1.mod2.varname". '''
+    if isinstance(model, basestring):
+        varname = model.split('.')[-1]
+        modules = '.'.join(model.split('.')[:-1])
+        module = __import__(modules, globals(), {}, ['dummy-not-used'], -1)
+        return getattr(module, varname)
+    else:
+        # Assume it's already loaded.
+        return model
+