Re-use method as default parameter of TableHandler add_column

There is no guarantee that the method will not raise a database error on the
first registration because it can rely on other tables being registered.
So the method must be called only when needed. This is when the table already
exists and has records. In this case other tables also already exist.

issue6409

trytond/backend/mysql/table.py

@@ -8,7 +8,6 @@ from trytond.backend.table import TableHandlerInterface
 
 logger = logging.getLogger(__name__)
 VARCHAR_SIZE_RE = re.compile('VARCHAR\(([0-9]+)\)')
-_NO_DEFAULT = object()
 
 
 class TableHandler(TableHandlerInterface):
@@ -181,8 +180,7 @@ class TableHandler(TableHandlerInterface):
                 self._column_definition(column_name, default=value)))
         self._update_definitions(columns=True)
 
-    def add_column(self, column_name, sql_type, default=_NO_DEFAULT,
-            comment=''):
+    def add_column(self, column_name, sql_type, default=None, comment=''):
         cursor = Transaction().connection.cursor()
         database = Transaction().database
 
@@ -236,13 +234,13 @@ class TableHandler(TableHandlerInterface):
         cursor.execute('ALTER TABLE `%s` ADD COLUMN `%s` %s' %
                 (self.table_name, column_name, column_type))
 
-        if default is not _NO_DEFAULT:
+        if default:
             # check if table is non-empty:
             cursor.execute('SELECT 1 FROM `%s` limit 1' % self.table_name)
             if cursor.rowcount:
                 # Populate column with default values:
                 cursor.execute('UPDATE `' + self.table_name + '` '
-                    'SET `' + column_name + '` = %s', (default,))
+                    'SET `' + column_name + '` = %s', (default(),))
 
         self._update_definitions(columns=True)
 

trytond/backend/postgresql/table.py

@@ -10,7 +10,6 @@ __all__ = ['TableHandler']
 
 logger = logging.getLogger(__name__)
 VARCHAR_SIZE_RE = re.compile('VARCHAR\(([0-9]+)\)')
-_NO_DEFAULT = object()
 
 
 class TableHandler(TableHandlerInterface):
@@ -238,8 +237,7 @@ class TableHandler(TableHandlerInterface):
                 'ALTER COLUMN "' + column_name + '" SET DEFAULT %s',
                 (value,))
 
-    def add_column(self, column_name, sql_type, default=_NO_DEFAULT,
-            comment=''):
+    def add_column(self, column_name, sql_type, default=None, comment=''):
         cursor = Transaction().connection.cursor()
         database = Transaction().database
 
@@ -299,13 +297,13 @@ class TableHandler(TableHandlerInterface):
             % (self.table_name, column_name, column_type))
         add_comment()
 
-        if default is not _NO_DEFAULT:
+        if default:
             # check if table is non-empty:
             cursor.execute('SELECT 1 FROM "%s" limit 1' % self.table_name)
             if cursor.rowcount:
                 # Populate column with default values:
                 cursor.execute('UPDATE "' + self.table_name + '" '
-                    'SET "' + column_name + '" = %s', (default,))
+                    'SET "' + column_name + '" = %s', (default(),))
 
         self._update_definitions(columns=True)
 

trytond/backend/sqlite/table.py

@@ -11,7 +11,6 @@ __all__ = ['TableHandler']
 
 logger = logging.getLogger(__name__)
 VARCHAR_SIZE_RE = re.compile('VARCHAR\(([0-9]+)\)')
-_NO_DEFAULT = object()
 
 
 class TableHandler(TableHandlerInterface):
@@ -177,8 +176,7 @@ class TableHandler(TableHandlerInterface):
     def db_default(self, column_name, value):
         warnings.warn('Unable to set default on column with SQLite backend')
 
-    def add_column(self, column_name, sql_type, default=_NO_DEFAULT,
-            comment=''):
+    def add_column(self, column_name, sql_type, default=None, comment=''):
         database = Transaction().database
         column_type = database.sql_type(sql_type)
         match = VARCHAR_SIZE_RE.match(sql_type)
@@ -187,7 +185,7 @@ class TableHandler(TableHandlerInterface):
         self._add_raw_column(column_name, column_type, default, field_size,
             comment)
 
-    def _add_raw_column(self, column_name, column_type, default=_NO_DEFAULT,
+    def _add_raw_column(self, column_name, column_type, default=None,
             field_size=None, string=''):
         if self.column_exist(column_name):
             base_type = column_type[0].upper()
@@ -231,13 +229,13 @@ class TableHandler(TableHandlerInterface):
         cursor.execute(('ALTER TABLE "%s" ADD COLUMN "%s" %s') %
                        (self.table_name, column_name, column_type))
 
-        if default is not _NO_DEFAULT:
+        if default:
             # check if table is non-empty:
             cursor.execute('SELECT 1 FROM "%s" limit 1' % self.table_name)
             if cursor.fetchone():
                 # Populate column with default values:
                 cursor.execute('UPDATE "' + self.table_name + '" '
-                    'SET "' + column_name + '" = ?', (default,))
+                    'SET "' + column_name + '" = ?', (default(),))
 
         self._update_definitions(columns=True)
 

trytond/backend/table.py

@@ -113,14 +113,13 @@ class TableHandlerInterface(object):
         '''
         raise NotImplementedError
 
-    def add_column(self, column_name, abstract_type, default=object(),
-            comment=''):
+    def add_column(self, column_name, abstract_type, default=None, comment=''):
         '''
         Add a column
 
         :param column_name: the column name
         :param abstract_type: the abstract type that will represent this column
-        :param default: the default value to use
+        :param default: the method that return default value to use
         :param comment: An optional comment on the column
         '''
         raise NotImplementedError

trytond/model/modelsql.py

@@ -150,17 +150,15 @@ class ModelSQL(ModelStorage):
             if not sql_type:
                 continue
 
-            # Using a dict to specify the default values allows to not override
-            # the 'default' default value specified in the backend which is an
-            # object() hack
-            kwargs = {}
+            default = None
             if field_name in cls._defaults:
-                default_ = cls._clean_defaults({
-                        field_name: cls._defaults[field_name](),
-                        })[field_name]
-                kwargs['default'] = field.sql_format(default_)
+                def default():
+                    default_ = cls._clean_defaults({
+                            field_name: cls._defaults[field_name](),
+                            })[field_name]
+                    return field.sql_format(default_)
 
-            table.add_column(field_name, field._sql_type, **kwargs)
+            table.add_column(field_name, field._sql_type, default=default)
             if cls._history:
                 history_table.add_column(field_name, field._sql_type)