db.supports_strict and table.strict properties, refs #344

Author: simonw

docs/python-api.rst

@@ -1609,8 +1609,8 @@ A more useful example: if you are working with `SpatiaLite <https://www.gaia-gis
 
 .. _python_api_introspection:
 
-Introspection
-=============
+Introspecting tables and views
+==============================
 
 If you have loaded an existing table or view, you can use introspection to find out more about it::
 
@@ -1741,6 +1741,18 @@ The ``.schema`` property outputs the table's schema as a SQL string::
         FOREIGN KEY ("qCareAssistant") REFERENCES [qCareAssistant](id),
         FOREIGN KEY ("qLegalStatus") REFERENCES [qLegalStatus](id))
 
+.. _python_api_introspection_strict:
+
+.strict
+-------
+
+The ``.strict`` property identifies if the table is a `SQLite STRICT table <https://www.sqlite.org/stricttables.html>`__.
+
+::
+
+    >>> db["ny_times_us_counties"].strict
+    False
+
 .. _python_api_introspection_indexes:
 
 .indexes

sqlite_utils/db.py

@@ -18,6 +18,7 @@
 import os
 import pathlib
 import re
+import secrets
 from sqlite_fts4 import rank_bm25  # type: ignore
 import sys
 import textwrap
@@ -521,6 +522,19 @@ def schema(self) -> str:
             sqls.append(sql)
         return "\n".join(sqls)
 
+    @property
+    def supports_strict(self):
+        try:
+            table_name = "t{}".format(secrets.token_hex(16))
+            with self.conn:
+                self.conn.execute(
+                    "create table {} (name text) strict".format(table_name)
+                )
+                self.conn.execute("drop table {}".format(table_name))
+            return True
+        except Exception as e:
+            return False
+
     @property
     def journal_mode(self) -> str:
         "Current ``journal_mode`` of this database."
@@ -1219,6 +1233,13 @@ def triggers_dict(self) -> Dict[str, str]:
         "``{trigger_name: sql}`` dictionary of triggers defined on this table."
         return {trigger.name: trigger.sql for trigger in self.triggers}
 
+    @property
+    def strict(self) -> bool:
+        "Is this a STRICT table?"
+        table_suffix = self.schema.split(")")[-1].strip().upper()
+        table_options = [bit.strip() for bit in table_suffix.split(",")]
+        return "STRICT" in table_options
+
     def create(
         self,
         columns: Dict[str, Any],

tests/test_introspect.py

@@ -252,15 +252,33 @@ def test_has_counts_triggers(fresh_db):
         ),
     ],
 )
-def test_virtual_table_using(sql, expected_name, expected_using):
-    db = Database(memory=True)
-    db.execute(sql)
-    assert db[expected_name].virtual_table_using == expected_using
-
-
-def test_use_rowid():
-    db = Database(memory=True)
-    db["rowid_table"].insert({"name": "Cleo"})
-    db["regular_table"].insert({"id": 1, "name": "Cleo"}, pk="id")
-    assert db["rowid_table"].use_rowid
-    assert not db["regular_table"].use_rowid
+def test_virtual_table_using(fresh_db, sql, expected_name, expected_using):
+    fresh_db.execute(sql)
+    assert fresh_db[expected_name].virtual_table_using == expected_using
+
+
+def test_use_rowid(fresh_db):
+    fresh_db["rowid_table"].insert({"name": "Cleo"})
+    fresh_db["regular_table"].insert({"id": 1, "name": "Cleo"}, pk="id")
+    assert fresh_db["rowid_table"].use_rowid
+    assert not fresh_db["regular_table"].use_rowid
+
+
+@pytest.mark.skipif(
+    not Database(memory=True).supports_strict,
+    reason="Needs SQLite version that supports strict",
+)
+@pytest.mark.parametrize(
+    "create_table,expected_strict",
+    (
+        ("create table t (id integer) strict", True),
+        ("create table t (id integer) STRICT", True),
+        ("create table t (id integer primary key) StriCt, WITHOUT ROWID", True),
+        ("create table t (id integer primary key) WITHOUT ROWID", False),
+        ("create table t (id integer)", False),
+    ),
+)
+def test_table_strict(fresh_db, create_table, expected_strict):
+    fresh_db.execute(create_table)
+    table = fresh_db["t"]
+    assert table.strict == expected_strict