Refactored get_max_name_length() to DatabaseOperations.max_name_length(). Refs #5106

git-svn-id: http://code.djangoproject.com/svn/django/trunk@5960 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/management/sql.py

@@ -148,7 +148,7 @@ def sql_delete(app, style):
                         (style.SQL_KEYWORD('ALTER TABLE'),
                         style.SQL_TABLE(backend.quote_name(table)),
                         style.SQL_KEYWORD(connection.ops.drop_foreignkey_sql()),
-                        style.SQL_FIELD(truncate_name(r_name, backend.get_max_name_length()))))
+                        style.SQL_FIELD(truncate_name(r_name, connection.ops.max_name_length()))))
                 del references_to_delete[model]
             if model._meta.has_auto_field and hasattr(backend, 'get_drop_sequence'):
                 output.append(backend.get_drop_sequence(model._meta.db_table))
@@ -297,7 +297,7 @@ def sql_for_pending_references(model, style, pending_references):
                 # So we are careful with character usage here.
                 r_name = '%s_refs_%s_%x' % (r_col, col, abs(hash((r_table, table))))
                 final_output.append(style.SQL_KEYWORD('ALTER TABLE') + ' %s ADD CONSTRAINT %s FOREIGN KEY (%s) REFERENCES %s (%s)%s;' % \
-                    (backend.quote_name(r_table), truncate_name(r_name, backend.get_max_name_length()),
+                    (backend.quote_name(r_table), truncate_name(r_name, connection.ops.max_name_length()),
                     backend.quote_name(r_col), backend.quote_name(table), backend.quote_name(col),
                     connection.ops.deferrable_sql()))
             del pending_references[model]

django/db/backends/__init__.py

@@ -119,3 +119,10 @@ class BaseDatabaseOperations(object):
         if offset and offset != 0:
             sql += " OFFSET %s" % offset
         return sql
+
+    def max_name_length(self):
+        """
+        Returns the maximum length of table and column names, or None if there
+        is no limit.
+        """
+        return None

django/db/backends/ado_mssql/base.py

@@ -106,9 +106,6 @@ def get_random_function_sql():
 def get_pk_default_value():
     return "DEFAULT"
 
-def get_max_name_length():
-    return None
-
 def get_start_transaction_sql():
     return "BEGIN;"
 

django/db/backends/dummy/base.py

@@ -45,7 +45,6 @@ dictfetchmany = complain
 dictfetchall = complain
 get_random_function_sql = complain
 get_pk_default_value = complain
-get_max_name_length = ignore
 get_start_transaction_sql = complain
 get_sql_flush = complain
 get_sql_sequence_reset = complain

django/db/backends/mysql/base.py

@@ -168,9 +168,6 @@ def get_random_function_sql():
 def get_pk_default_value():
     return "DEFAULT"
 
-def get_max_name_length():
-    return None;
-
 def get_start_transaction_sql():
     return "BEGIN;"
 

django/db/backends/mysql_old/base.py

@@ -187,9 +187,6 @@ def get_random_function_sql():
 def get_pk_default_value():
     return "DEFAULT"
 
-def get_max_name_length():
-    return None;
-
 def get_start_transaction_sql():
     return "BEGIN;"
 

django/db/backends/oracle/base.py

@@ -58,7 +58,7 @@ class DatabaseOperations(BaseDatabaseOperations):
         return " DEFERRABLE INITIALLY DEFERRED"
 
     def last_insert_id(self, cursor, table_name, pk_name):
-        sq_name = util.truncate_name(table_name, get_max_name_length()-3)
+        sq_name = util.truncate_name(table_name, self.max_name_length() - 3)
         cursor.execute('SELECT %s_sq.currval FROM dual' % sq_name)
         return cursor.fetchone()[0]
 
@@ -67,6 +67,9 @@ class DatabaseOperations(BaseDatabaseOperations):
         # Instead, they are handled in django/db/backends/oracle/query.py.
         return ""
 
+    def max_name_length(self):
+        return 30
+
 class DatabaseWrapper(BaseDatabaseWrapper):
     ops = DatabaseOperations()
 
@@ -170,7 +173,7 @@ def quote_name(name):
     # always defaults to uppercase.
     # We simplify things by making Oracle identifiers always uppercase.
     if not name.startswith('"') and not name.endswith('"'):
-        name = '"%s"' % util.truncate_name(name.upper(), get_max_name_length())
+        name = '"%s"' % util.truncate_name(name.upper(), DatabaseOperations().max_name_length())
     return name.upper()
 
 dictfetchone = util.dictfetchone
@@ -189,9 +192,6 @@ def get_random_function_sql():
 def get_pk_default_value():
     return "DEFAULT"
 
-def get_max_name_length():
-    return 30
-
 def get_start_transaction_sql():
     return None
 
@@ -249,7 +249,7 @@ def get_sql_flush(style, tables, sequences):
         return []
 
 def get_sequence_name(table):
-    name_length = get_max_name_length() - 3
+    name_length = DatabaseOperations().max_name_length() - 3
     return '%s_SQ' % util.truncate_name(table, name_length).upper()
 
 def get_sql_sequence_reset(style, model_list):
@@ -271,7 +271,7 @@ def get_sql_sequence_reset(style, model_list):
     return output
 
 def get_trigger_name(table):
-    name_length = get_max_name_length() - 3
+    name_length = DatabaseOperations().max_name_length() - 3
     return '%s_TR' % util.truncate_name(table, name_length).upper()
 
 def get_query_set_class(DefaultQuerySet):

django/db/backends/postgresql/base.py

@@ -137,9 +137,6 @@ def get_random_function_sql():
 def get_pk_default_value():
     return "DEFAULT"
 
-def get_max_name_length():
-    return None
-
 def get_start_transaction_sql():
     return "BEGIN;"
 

django/db/backends/postgresql_psycopg2/base.py

@@ -91,9 +91,6 @@ def get_random_function_sql():
 def get_pk_default_value():
     return "DEFAULT"
 
-def get_max_name_length():
-    return None
-
 def get_start_transaction_sql():
     return "BEGIN;"
 

django/db/backends/sqlite3/base.py

@@ -121,9 +121,6 @@ def get_random_function_sql():
 def get_pk_default_value():
     return "NULL"
 
-def get_max_name_length():
-    return None
-
 def get_start_transaction_sql():
     return "BEGIN;"
 

django/db/models/options.py

@@ -63,7 +63,7 @@ class Options(object):
         del self.meta
 
     def _prepare(self, model):
-        from django.db import backend
+        from django.db import connection
         from django.db.backends.util import truncate_name
         if self.order_with_respect_to:
             self.order_with_respect_to = self.get_field(self.order_with_respect_to)
@@ -79,8 +79,7 @@ class Options(object):
         # If the db_table wasn't provided, use the app_label + module_name.
         if not self.db_table:
             self.db_table = "%s_%s" % (self.app_label, self.module_name)
-            self.db_table = truncate_name(self.db_table,
+            self.db_table = truncate_name(self.db_table, connection.ops.max_name_length())
-                                          backend.get_max_name_length())
 
     def add_field(self, field):
         # Insert the given field in the order in which it was created, using