prepare_connection plugin hook

Closes:
- #574

Refs #567

---------

Co-authored-by: Simon Willison <swillison@gmail.com>

sqlite_utils/__init__.py

@@ -1,6 +1,6 @@
-from .db import Database
 from .utils import suggest_column_types
 from .hookspecs import hookimpl
 from .hookspecs import hookspec
+from .db import Database
 
 __all__ = ["Database", "suggest_column_types", "hookimpl", "hookspec"]

sqlite_utils/db.py

@@ -37,6 +37,7 @@ from typing import (
     Tuple,
 )
 import uuid
+from sqlite_utils.plugins import pm
 
 try:
     from sqlite_dump import iterdump
@@ -342,6 +343,8 @@ class Database:
         self._registered_functions: set = set()
         self.use_counts_table = use_counts_table
 
+        pm.hook.prepare_connection(conn=self.conn)
+
     def close(self):
         "Close the SQLite connection, and the underlying database file"
         self.conn.close()

sqlite_utils/hookspecs.py

@@ -8,3 +8,8 @@ hookimpl = HookimplMarker("sqlite_utils")
 @hookspec
 def register_commands(cli):
     """Register additional CLI commands, e.g. 'sqlite-utils mycommand ...'"""
+
+
+@hookspec
+def prepare_connection(conn):
+    """Modify SQLite connection in some way e.g. register custom SQL functions"""