Add default typecast for sql_identifier

docs/contents/changelog.rst

@@ -6,11 +6,13 @@ Version 5.2.5 (to be released)
 - This version officially supports the new Python 3.11 and PostgreSQL 15.
 - Two more improvements in the `inserttable()` method of the `pg` module
   (thanks to Justin Pryzby for this contribution):
+
     - error handling has been improved (#72)
     - the method now returns the number of inserted rows (#73)
 - Another improvement in the `pg` module (#83):
     - generated columns can be requested with the `get_generated()` method
     - generated columns are ignored by the insert, update and upsert method
+- Avoid internal query and error when casting the `sql_identifier` type (#82)
 
 Version 5.2.4 (2022-03-26)
 --------------------------

pg.py

@@ -1066,7 +1066,7 @@ class Typecasts(dict):
     # (str functions are ignored but have been added for faster access)
     defaults = {
         'char': str, 'bpchar': str, 'name': str,
-        'text': str, 'varchar': str,
+        'text': str, 'varchar': str, 'sql_identifier': str,
         'bool': cast_bool, 'bytea': unescape_bytea,
         'int2': int, 'int4': int, 'serial': int, 'int8': long, 'oid': int,
         'hstore': cast_hstore, 'json': cast_json, 'jsonb': cast_json,

pgdb.py

@@ -555,7 +555,7 @@ class Typecasts(dict):
     # (str functions are ignored but have been added for faster access)
     defaults = {
         'char': str, 'bpchar': str, 'name': str,
-        'text': str, 'varchar': str,
+        'text': str, 'varchar': str, 'sql_identifier': str,
         'bool': cast_bool, 'bytea': unescape_bytea,
         'int2': int, 'int4': int, 'serial': int, 'int8': long, 'oid': int,
         'hstore': cast_hstore, 'json': jsondecode, 'jsonb': jsondecode,

tests/test_classic_dbwrapper.py

@@ -4899,7 +4899,7 @@ def testMunging(self):
         else:
             self.assertNotIn('oid(t)', r)
 
-    def testQeryInformationSchema(self):
+    def testQueryInformationSchema(self):
         q = "column_name"
         if self.db.server_version < 110000:
             q += "::text"  # old version does not have sql_identifier array