From b4f09146d342ba72190f9a8543a44ccd6ea06b02 Mon Sep 17 00:00:00 2001
From: Simon Willison <swillison@gmail.com>
Date: Sun, 3 Jan 2021 12:41:24 -0800
Subject: [PATCH] table.has_counts_triggers property, refs #219

---
 docs/python-api.rst      | 18 ++++++++++++++----
 sqlite_utils/cli.py      | 14 ++++++++++++++
 sqlite_utils/db.py       | 10 ++++++++++
 tests/test_introspect.py |  8 ++++++++
 4 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/docs/python-api.rst b/docs/python-api.rst
index b02fafa..8f943f6 100644
--- a/docs/python-api.rst
+++ b/docs/python-api.rst
@@ -1469,7 +1469,7 @@ The ``.triggers`` property lists database triggers. It can be used on both datab
     >>> db.triggers
     ... similar output to db["authors"].triggers
 
-The ``table.triggers_dict`` property returns the triggers for that table as a dictionary mapping their names to their SQL definitions.
+The ``.triggers_dict`` property returns the triggers for that table as a dictionary mapping their names to their SQL definitions.
 
 ::
 
@@ -1491,15 +1491,25 @@ The ``detect_fts()`` method returns the associated SQLite FTS table name, if one
 
 ::
 
-    >> db["authors"].detect_fts()
+    >>> db["authors"].detect_fts()
     "authors_fts"
 
 The ``.virtual_table_using`` property reveals if a table is a virtual table. It returns ``None`` for regular tables and the upper case version of the type of virtual table otherwise. For example::
 
-    >> db["authors"].enable_fts(["name"])
-    >> db["authors_fts"].virtual_table_using
+    >>> db["authors"].enable_fts(["name"])
+    >>> db["authors_fts"].virtual_table_using
     "FTS5"
 
+The ``.has_counts_triggers`` property shows if a table has been configured with triggers for updating a ``_counts`` table, as described in :ref:`python_api_cached_table_counts`.
+
+::
+
+    >>> db["authors"].has_counts_triggers
+    False
+    >>> db["authors"].enable_counts()
+    >>> db["authors"].has_counts_triggers
+    True
+
 .. _python_api_fts:
 
 Enabling full-text search
diff --git a/sqlite_utils/cli.py b/sqlite_utils/cli.py
index 0388961..0bc03fe 100644
--- a/sqlite_utils/cli.py
+++ b/sqlite_utils/cli.py
@@ -571,6 +571,20 @@ def enable_counts(path, tables, load_extension):
             db[table].enable_counts()
 
 
+@cli.command(name="reset-counts")
+@click.argument(
+    "path",
+    type=click.Path(exists=True, file_okay=True, dir_okay=False, allow_dash=False),
+    required=True,
+)
+@load_extension_option
+def reset_counts(path, load_extension):
+    "Reset calculated counts in the _counts table"
+    db = sqlite_utils.Database(path)
+    _load_extensions(db, load_extension)
+    db.reset_counts()
+
+
 def insert_upsert_options(fn):
     for decorator in reversed(
         (
diff --git a/sqlite_utils/db.py b/sqlite_utils/db.py
index f1f3de6..bc954e5 100644
--- a/sqlite_utils/db.py
+++ b/sqlite_utils/db.py
@@ -1268,6 +1268,16 @@ class Table(Queryable):
             self.db.conn.executescript(sql)
         self.db.use_counts_table = True
 
+    @property
+    def has_counts_triggers(self):
+        trigger_names = {
+            "{table}{counts_table}_{suffix}".format(
+                counts_table=self.db._counts_table_name, table=self.name, suffix=suffix
+            )
+            for suffix in ["insert", "delete"]
+        }
+        return trigger_names.issubset(self.triggers_dict.keys())
+
     def enable_fts(
         self,
         columns,
diff --git a/tests/test_introspect.py b/tests/test_introspect.py
index 9a37001..73102f8 100644
--- a/tests/test_introspect.py
+++ b/tests/test_introspect.py
@@ -154,6 +154,14 @@ def test_triggers_and_triggers_dict(fresh_db):
     assert fresh_db.triggers_dict == expected_triggers
 
 
+def test_has_counts_triggers(fresh_db):
+    authors = fresh_db["authors"]
+    authors.insert({"name": "Frank Herbert"})
+    assert not authors.has_counts_triggers
+    authors.enable_counts()
+    assert authors.has_counts_triggers
+
+
 @pytest.mark.parametrize(
     "sql,expected_name,expected_using",
     [