Fix and test issue 118. Clarify genmodel transformations.

migrate/tests/versioning/test_genmodel.py

@@ -35,7 +35,7 @@ class TestSchemaDiff(fixture.DB):
 
     def _applyLatestModel(self):
         diff = schemadiff.getDiffOfModelAgainstDatabase(self.meta, self.engine, excludeTables=['migrate_version'])
-        genmodel.ModelGenerator(diff,self.engine).applyModel()
+        genmodel.ModelGenerator(diff,self.engine).runB2A()
 
     @fixture.usedb()
     def test_functional(self):
@@ -57,16 +57,30 @@ class TestSchemaDiff(fixture.DB):
 
         # Check Python upgrade and downgrade of database from updated model.
         diff = schemadiff.getDiffOfModelAgainstDatabase(self.meta, self.engine, excludeTables=['migrate_version'])
-        decls, upgradeCommands, downgradeCommands = genmodel.ModelGenerator(diff,self.engine).toUpgradeDowngradePython()
+        decls, upgradeCommands, downgradeCommands = genmodel.ModelGenerator(diff,self.engine).genB2AMigration()
-        self.assertEqualsIgnoreWhitespace(decls, '''
+
-        from migrate.changeset import schema
+        # Feature test for a recent SQLa feature;
-        meta = MetaData()
+        # expect different output in that case.
-        tmp_schemadiff = Table('tmp_schemadiff', meta,
+        if repr(String()) == 'String()':
-            Column('id', Integer(), primary_key=True, nullable=False),
+            self.assertEqualsIgnoreWhitespace(decls, '''
-            Column('name', UnicodeText(length=None)),
+            from migrate.changeset import schema
-            Column('data', UnicodeText(length=None)),
+            meta = MetaData()
-        )
+            tmp_schemadiff = Table('tmp_schemadiff', meta,
-        ''')
+                Column('id', Integer, primary_key=True, nullable=False),
+                Column('name', UnicodeText),
+                Column('data', UnicodeText),
+            )
+            ''')
+        else:
+            self.assertEqualsIgnoreWhitespace(decls, '''
+            from migrate.changeset import schema
+            meta = MetaData()
+            tmp_schemadiff = Table('tmp_schemadiff', meta,
+                Column('id', Integer(), primary_key=True, nullable=False),
+                Column('name', UnicodeText(length=None)),
+                Column('data', UnicodeText(length=None)),
+            )
+            ''')
         self.assertEqualsIgnoreWhitespace(upgradeCommands,
             '''meta.bind = migrate_engine
             tmp_schemadiff.create()''')
@@ -80,7 +94,7 @@ class TestSchemaDiff(fixture.DB):
 
         # Check Python code gen from database.
         diff = schemadiff.getDiffOfModelAgainstDatabase(MetaData(), self.engine, excludeTables=['migrate_version'])
-        src = genmodel.ModelGenerator(diff,self.engine).toPython()
+        src = genmodel.ModelGenerator(diff,self.engine).genBDefinition()
 
         exec src in locals()
 

migrate/tests/versioning/test_script.py

@@ -161,23 +161,44 @@ def upgrade(migrate_engine):
         self.assertTrue('User.create()' in source_script)
         self.assertTrue('User.drop()' in source_script)
 
-    #@fixture.usedb()
+    @fixture.usedb()
-    #def test_make_update_script_for_model_equals(self):
+    def test_make_update_script_for_equal_models(self):
-    #    """Try to make update script from two identical models"""
+        """Try to make update script from two identical models"""
 
-    #    self.setup_model_params()
+        self.setup_model_params()
-    #    self.write_file(self.first_model_path, self.base_source + self.model_source)
+        self.write_file(self.first_model_path, self.base_source + self.model_source)
-    #    self.write_file(self.second_model_path, self.base_source + self.model_source)
+        self.write_file(self.second_model_path, self.base_source + self.model_source)
 
-    #    source_script = self.pyscript.make_update_script_for_model(
+        source_script = self.pyscript.make_update_script_for_model(
-    #        engine=self.engine,
+            engine=self.engine,
-    #        oldmodel=load_model('testmodel_first:meta'),
+            oldmodel=load_model('testmodel_first:meta'),
-    #        model=load_model('testmodel_second:meta'),
+            model=load_model('testmodel_second:meta'),
-    #        repository=self.repo_path,
+            repository=self.repo_path,
-    #    )
+        )
 
-    #    self.assertFalse('User.create()' in source_script)
+        self.assertFalse('User.create()' in source_script)
-    #    self.assertFalse('User.drop()' in source_script)
+        self.assertFalse('User.drop()' in source_script)
+
+    @fixture.usedb()
+    def test_make_update_script_direction(self):
+        """Check update scripts go in the right direction"""
+
+        self.setup_model_params()
+        self.write_file(self.first_model_path, self.base_source)
+        self.write_file(self.second_model_path, self.base_source + self.model_source)
+
+        source_script = self.pyscript.make_update_script_for_model(
+            engine=self.engine,
+            oldmodel=load_model('testmodel_first:meta'),
+            model=load_model('testmodel_second:meta'),
+            repository=self.repo_path,
+        )
+
+        self.assertTrue(0
+                        < source_script.find('upgrade')
+                        < source_script.find('User.create()')
+                        < source_script.find('downgrade')
+                        < source_script.find('User.drop()'))
 
     def setup_model_params(self):
         self.script_path = self.tmp_py()
@@ -195,6 +216,8 @@ User = Table('User', meta,
 
         self.repo = repository.Repository.create(self.repo_path, 'repo')
         self.pyscript = PythonScript.create(self.script_path)
+        sys.modules.pop('testmodel_first', None)
+        sys.modules.pop('testmodel_second', None)
 
     def write_file(self, path, contents):
         f = open(path, 'w')

migrate/versioning/genmodel.py

@@ -1,9 +1,9 @@
 """
-   Code to generate a Python model from a database or differences
+Code to generate a Python model from a database or differences
-   between a model and database.
+between a model and database.
 
-   Some of this is borrowed heavily from the AutoCode project at:
+Some of this is borrowed heavily from the AutoCode project at:
-   http://code.google.com/p/sqlautocode/
+http://code.google.com/p/sqlautocode/
 """
 
 import sys
@@ -34,6 +34,13 @@ Base = declarative.declarative_base()
 
 
 class ModelGenerator(object):
+    """Various transformations from an A, B diff.
+
+    In the implementation, A tends to be called the model and B
+    the database (although this is not true of all diffs).
+    The diff is directionless, but transformations apply the diff
+    in a particular direction, described in the method name.
+    """
 
     def __init__(self, diff, engine, declarative=False):
         self.diff = diff
@@ -89,7 +96,7 @@ class ModelGenerator(object):
         else:
             return """Column(%(name)r, %(commonStuff)s)""" % data
 
-    def getTableDefn(self, table):
+    def _getTableDefn(self, table):
         out = []
         tableName = table.name
         if self.declarative:
@@ -118,8 +125,14 @@ class ModelGenerator(object):
                 for name in names:
                     yield metadata.tables.get(name)
 
-    def toPython(self):
+    def genBDefinition(self):
-        """Assume database is current and model is empty."""
+        """Generates the source code for a definition of B.
+
+        Assumes a diff where A is empty.
+
+        Was: toPython. Assume database (B) is current and model (A) is empty.
+        """
+
         out = []
         if self.declarative:
             out.append(DECLARATIVE_HEADER)
@@ -127,17 +140,22 @@ class ModelGenerator(object):
             out.append(HEADER)
         out.append("")
         for table in self._get_tables(missingA=True):
-            out.extend(self.getTableDefn(table))
+            out.extend(self._getTableDefn(table))
         return '\n'.join(out)
 
-    def toUpgradeDowngradePython(self, indent='    '):
+    def genB2AMigration(self, indent='    '):
-        ''' Assume model is most current and database is out-of-date. '''
+        '''Generate a migration from B to A.
+
+        Was: toUpgradeDowngradePython
+        Assume model (A) is most current and database (B) is out-of-date.
+        '''
+
         decls = ['from migrate.changeset import schema',
                  'meta = MetaData()']
         for table in self._get_tables(
             missingA=True,missingB=True,modified=True
             ):
-            decls.extend(self.getTableDefn(table))
+            decls.extend(self._getTableDefn(table))
 
         upgradeCommands, downgradeCommands = [], []
         for tableName in self.diff.tables_missing_from_A:
@@ -175,16 +193,21 @@ class ModelGenerator(object):
             '\n'.join([pre_command] + ['%s%s' % (indent, line) for line in downgradeCommands]))
 
     def _db_can_handle_this_change(self,td):
+        """Check if the database can handle going from B to A."""
+
         if (td.columns_missing_from_B
             and not td.columns_missing_from_A
             and not td.columns_different):
-            # Even sqlite can handle this.
+            # Even sqlite can handle column additions.
             return True
         else:
             return not self.engine.url.drivername.startswith('sqlite')
 
-    def applyModel(self):
+    def runB2A(self):
-        """Apply model to current database."""
+        """Goes from B to A.
+
+        Was: applyModel. Apply model (A) to current database (B).
+        """
 
         meta = sqlalchemy.MetaData(self.engine)
 

migrate/versioning/schema.py

@@ -117,7 +117,7 @@ class ControlledSchema(object):
         diff = schemadiff.getDiffOfModelAgainstDatabase(
             model, self.engine, excludeTables=[self.repository.version_table]
             )
-        genmodel.ModelGenerator(diff,self.engine).applyModel()
+        genmodel.ModelGenerator(diff,self.engine).runB2A()
 
         self.update_repository_table(self.version, int(self.repository.latest))
 
@@ -217,4 +217,4 @@ class ControlledSchema(object):
         diff = schemadiff.getDiffOfModelAgainstDatabase(
             MetaData(), engine, excludeTables=[repository.version_table]
             )
-        return genmodel.ModelGenerator(diff, engine, declarative).toPython()
+        return genmodel.ModelGenerator(diff, engine, declarative).genBDefinition()

migrate/versioning/script/py.py

@@ -61,12 +61,12 @@ class PythonScript(base.BaseScript):
 
         # Compute differences.
         diff = schemadiff.getDiffOfModelAgainstModel(
-            oldmodel,
             model,
+            oldmodel,
             excludeTables=[repository.version_table])
         # TODO: diff can be False (there is no difference?)
         decls, upgradeCommands, downgradeCommands = \
-            genmodel.ModelGenerator(diff,engine).toUpgradeDowngradePython()
+            genmodel.ModelGenerator(diff,engine).genB2AMigration()
 
         # Store differences into file.
         src = Template(opts.pop('templates_path', None)).get_script(opts.pop('templates_theme', None))