[3.0.x] Fixed #31751 -- Fixed database introspection with cx_Oracle 8.

Backport of 615e32162ff646db3456b90fb4eaaecc33dd3e4e from master

3 files changed, 46 insertions, 18 deletions

diff --git a/django/contrib/gis/db/backends/oracle/introspection.py b/django/contrib/gis/db/backends/oracle/introspection.py
index 5e71c84fdd..80899b33d7 100644
--- a/django/contrib/gis/db/backends/oracle/introspection.py
+++ b/django/contrib/gis/db/backends/oracle/introspection.py
@@ -1,14 +1,19 @@
 import cx_Oracle
 
 from django.db.backends.oracle.introspection import DatabaseIntrospection
+from django.utils.functional import cached_property
 
 
 class OracleIntrospection(DatabaseIntrospection):
     # Associating any OBJECTVAR instances with GeometryField.  Of course,
     # this won't work right on Oracle objects that aren't MDSYS.SDO_GEOMETRY,
     # but it is the only object type supported within Django anyways.
-    data_types_reverse = DatabaseIntrospection.data_types_reverse.copy()
-    data_types_reverse[cx_Oracle.OBJECT] = 'GeometryField'
+    @cached_property
+    def data_types_reverse(self):
+        return {
+            **super().data_types_reverse,
+            cx_Oracle.OBJECT: 'GeometryField',
+        }
 
     def get_geometry_type(self, table_name, description):
         with self.connection.cursor() as cursor:
diff --git a/django/db/backends/oracle/base.py b/django/db/backends/oracle/base.py
index 86650a894e..ec993bbcfd 100644
--- a/django/db/backends/oracle/base.py
+++ b/django/db/backends/oracle/base.py
@@ -311,6 +311,10 @@ class DatabaseWrapper(BaseDatabaseWrapper):
             return True
 
     @cached_property
+    def cx_oracle_version(self):
+        return tuple(int(x) for x in Database.version.split('.'))
+
+    @cached_property
     def oracle_version(self):
         with self.temporary_connection():
             return tuple(int(x) for x in self.connection.version.split('.'))
diff --git a/django/db/backends/oracle/introspection.py b/django/db/backends/oracle/introspection.py
index 2322ae0b5d..1ad0c9e8d7 100644
--- a/django/db/backends/oracle/introspection.py
+++ b/django/db/backends/oracle/introspection.py
@@ -6,29 +6,48 @@ from django.db import models
 from django.db.backends.base.introspection import (
     BaseDatabaseIntrospection, FieldInfo as BaseFieldInfo, TableInfo,
 )
+from django.utils.functional import cached_property
 
 FieldInfo = namedtuple('FieldInfo', BaseFieldInfo._fields + ('is_autofield',))
 
 
 class DatabaseIntrospection(BaseDatabaseIntrospection):
-    # Maps type objects to Django Field types.
-    data_types_reverse = {
-        cx_Oracle.BLOB: 'BinaryField',
-        cx_Oracle.CLOB: 'TextField',
-        cx_Oracle.DATETIME: 'DateField',
-        cx_Oracle.FIXED_CHAR: 'CharField',
-        cx_Oracle.FIXED_NCHAR: 'CharField',
-        cx_Oracle.INTERVAL: 'DurationField',
-        cx_Oracle.NATIVE_FLOAT: 'FloatField',
-        cx_Oracle.NCHAR: 'CharField',
-        cx_Oracle.NCLOB: 'TextField',
-        cx_Oracle.NUMBER: 'DecimalField',
-        cx_Oracle.STRING: 'CharField',
-        cx_Oracle.TIMESTAMP: 'DateTimeField',
-    }
-
     cache_bust_counter = 1
 
+    # Maps type objects to Django Field types.
+    @cached_property
+    def data_types_reverse(self):
+        if self.connection.cx_oracle_version < (8,):
+            return {
+                cx_Oracle.BLOB: 'BinaryField',
+                cx_Oracle.CLOB: 'TextField',
+                cx_Oracle.DATETIME: 'DateField',
+                cx_Oracle.FIXED_CHAR: 'CharField',
+                cx_Oracle.FIXED_NCHAR: 'CharField',
+                cx_Oracle.INTERVAL: 'DurationField',
+                cx_Oracle.NATIVE_FLOAT: 'FloatField',
+                cx_Oracle.NCHAR: 'CharField',
+                cx_Oracle.NCLOB: 'TextField',
+                cx_Oracle.NUMBER: 'DecimalField',
+                cx_Oracle.STRING: 'CharField',
+                cx_Oracle.TIMESTAMP: 'DateTimeField',
+            }
+        else:
+            return {
+                cx_Oracle.DB_TYPE_DATE: 'DateField',
+                cx_Oracle.DB_TYPE_BINARY_DOUBLE: 'FloatField',
+                cx_Oracle.DB_TYPE_BLOB: 'BinaryField',
+                cx_Oracle.DB_TYPE_CHAR: 'CharField',
+                cx_Oracle.DB_TYPE_CLOB: 'TextField',
+                cx_Oracle.DB_TYPE_INTERVAL_DS: 'DurationField',
+                cx_Oracle.DB_TYPE_NCHAR: 'CharField',
+                cx_Oracle.DB_TYPE_NCLOB: 'TextField',
+                cx_Oracle.DB_TYPE_NVARCHAR: 'CharField',
+                cx_Oracle.DB_TYPE_NUMBER: 'DecimalField',
+                cx_Oracle.DB_TYPE_TIMESTAMP: 'DateTimeField',
+                cx_Oracle.DB_TYPE_VARCHAR: 'CharField',
+            }
+
     def get_field_type(self, data_type, description):
         if data_type == cx_Oracle.NUMBER:
             precision, scale = description[4:6]