From 61e9937224fc15f2374502edcb50d8702d173af7 Mon Sep 17 00:00:00 2001
From: Charles Leifer <coleifer@gmail.com>
Date: Tue, 10 Jan 2023 08:26:44 -0600
Subject: [PATCH] Add column decltype to cursor description.

---
 src/cursor.c  | 23 +++++++++++++++++++++--
 test/dbapi.py | 29 ++++++++++++++++++++++++++++-
 2 files changed, 49 insertions(+), 3 deletions(-)

diff --git a/src/cursor.c b/src/cursor.c
index 553b56c..2ede578 100644
--- a/src/cursor.c
+++ b/src/cursor.c
@@ -219,6 +219,15 @@ _pysqlite_build_column_name(pysqlite_Cursor *self, const char *colname)
     return PyUnicode_FromStringAndSize(colname, len);
 }
 
+static PyObject *
+_pysqlite_build_column_decltype(pysqlite_Cursor *self, const char *decltype)
+{
+    if (!decltype) {
+        Py_RETURN_NONE;
+    }
+    return PyUnicode_FromStringAndSize(decltype, strlen(decltype));
+}
+
 /*
  * Returns a row from the currently active SQLite statement
  *
@@ -378,6 +387,7 @@ _pysqlite_query_execute(pysqlite_Cursor* self, int multiple, PyObject* args)
     PyObject* result;
     int numcols;
     PyObject* column_name;
+    PyObject* column_decltype;
     PyObject* second_argument = NULL;
     sqlite_int64 lastrowid;
 
@@ -541,6 +551,7 @@ _pysqlite_query_execute(pysqlite_Cursor* self, int multiple, PyObject* args)
             }
             for (i = 0; i < numcols; i++) {
                 const char *colname;
+                const char *decltype;
                 colname = sqlite3_column_name(self->statement->st, i);
                 if (colname == NULL) {
                     PyErr_NoMemory();
@@ -550,10 +561,18 @@ _pysqlite_query_execute(pysqlite_Cursor* self, int multiple, PyObject* args)
                 if (!column_name) {
                     goto error;
                 }
-                PyObject *descriptor = PyTuple_Pack(7, column_name,
+                decltype = sqlite3_column_decltype(self->statement->st, i);
+                column_decltype = _pysqlite_build_column_decltype(self, decltype);
+                if (!column_decltype) {
+                    Py_DECREF(column_name);
+                    goto error;
+                }
+
+                PyObject *descriptor = PyTuple_Pack(7, column_name, column_decltype,
                                                     Py_None, Py_None, Py_None,
-                                                    Py_None, Py_None, Py_None);
+                                                    Py_None, Py_None);
                 Py_DECREF(column_name);
+                Py_DECREF(column_decltype);
                 if (descriptor == NULL) {
                     goto error;
                 }
diff --git a/test/dbapi.py b/test/dbapi.py
index 68fe46d..6febf85 100644
--- a/test/dbapi.py
+++ b/test/dbapi.py
@@ -1017,6 +1017,32 @@ class ClosedCurTests(unittest.TestCase):
                 method(*params)
 
 
+class SqliteColumnTypeTests(unittest.TestCase):
+    def setUp(self):
+        self.cx = sqlite.connect(':memory:')
+        self.cx.execute('create table test(a text, b datetime)')
+        self.cx.execute('create view test_view as select * from test')
+
+    def CheckDeclTypes(self):
+        curs = self.cx.execute('select * from test')
+        self.assertEqual(curs.description, (
+            ('a', 'TEXT', None, None, None, None, None),
+            ('b', 'datetime', None, None, None, None, None),
+        ))
+
+        curs = self.cx.execute('select * from test_view')
+        self.assertEqual(curs.description, (
+            ('a', 'TEXT', None, None, None, None, None),
+            ('b', 'datetime', None, None, None, None, None),
+        ))
+
+        # Expressions return NULL decltype, reported as None.
+        curs = self.cx.execute('select b + b as c from test_view')
+        self.assertEqual(curs.description, (
+            ('c', None, None, None, None, None, None),
+        ))
+
+
 class SqliteOnConflictTests(unittest.TestCase):
     """
     Tests for SQLite's "insert on conflict" feature.
@@ -1181,6 +1207,7 @@ def suite():
     ext_suite = unittest.makeSuite(ExtensionTests, "Check")
     closed_con_suite = unittest.makeSuite(ClosedConTests, "Check")
     closed_cur_suite = unittest.makeSuite(ClosedCurTests, "Check")
+    columntypes_suite = unittest.makeSuite(SqliteColumnTypeTests, "Check")
     on_conflict_suite = unittest.makeSuite(SqliteOnConflictTests, "Check")
     blob_suite = unittest.makeSuite(BlobTests, "Check")
     closed_blob_suite = unittest.makeSuite(ClosedBlobTests, "Check")
@@ -1188,7 +1215,7 @@ def suite():
     return unittest.TestSuite((
         module_suite, connection_suite, cursor_suite, thread_suite,
         constructor_suite, ext_suite, closed_con_suite, closed_cur_suite,
-        on_conflict_suite, blob_suite, closed_blob_suite,
+        columntypes_suite, on_conflict_suite, blob_suite, closed_blob_suite,
         blob_context_manager_suite,
     ))