From 7a344ce76339170f4bba74a3658677790f05736d Mon Sep 17 00:00:00 2001
From: Dmitry Maslennikov <mrdaimor@gmail.com>
Date: Mon, 14 Nov 2022 15:34:14 +0400
Subject: [PATCH] workaround for delete all with foreign keys

---
 sqlalchemy_iris/base.py         | 15 +++++++++++++++
 sqlalchemy_iris/requirements.py | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)

diff --git a/sqlalchemy_iris/base.py b/sqlalchemy_iris/base.py
index 99e21d8..d2a12ec 100644
--- a/sqlalchemy_iris/base.py
+++ b/sqlalchemy_iris/base.py
@@ -348,6 +348,21 @@ def _get_limit_or_fetch(self, select):
         else:
             return select._fetch_clause
 
+    def visit_delete(self, delete_stmt, **kw):
+        if not delete_stmt._where_criteria and delete_stmt.table.foreign_keys:
+            # https://community.intersystems.com/post/sql-foreign-key-constraint-check-delete
+            table = delete_stmt.table
+            nocheck = False
+            for fk in table.foreign_keys:
+                nocheck = not fk.ondelete and fk.parent.table == table
+                if not nocheck:
+                    break
+
+            if nocheck is True:
+                delete_stmt = delete_stmt.prefix_with('%NOCHECK', dialect='iris')
+        text = super().visit_delete(delete_stmt, **kw)
+        return text
+
     def visit_true(self, expr, **kw):
         return "1"
 
diff --git a/sqlalchemy_iris/requirements.py b/sqlalchemy_iris/requirements.py
index 6f944af..d278ae4 100644
--- a/sqlalchemy_iris/requirements.py
+++ b/sqlalchemy_iris/requirements.py
@@ -93,3 +93,36 @@ def binary_literals(self):
 
         return exclusions.closed()
 
+    @property
+    def foreign_key_constraint_option_reflection_ondelete(self):
+        return exclusions.open()
+
+    @property
+    def fk_constraint_option_reflection_ondelete_restrict(self):
+        return exclusions.closed()
+
+    @property
+    def fk_constraint_option_reflection_ondelete_noaction(self):
+        return exclusions.open()
+
+    @property
+    def foreign_key_constraint_option_reflection_onupdate(self):
+        return exclusions.open()
+
+    @property
+    def fk_constraint_option_reflection_onupdate_restrict(self):
+        return exclusions.closed()
+
+
+    @property
+    def precision_numerics_many_significant_digits(self):
+        """target backend supports values with many digits on both sides,
+        such as 319438950232418390.273596, 87673.594069654243
+
+        """
+        return exclusions.closed()
+
+    @property
+    def symbol_names_w_double_quote(self):
+        """Target driver can create tables with a name like 'some " table'"""
+        return exclusions.closed()