sqlite: add `close` method, and an `is_open` field (#7382)

vlib/sqlite/sqlite.v

@@ -20,8 +20,10 @@ struct C.sqlite3_stmt {
 
 //
 pub struct DB {
+pub mut:
+	is_open bool
 mut:
-	conn &C.sqlite3
+	conn    &C.sqlite3
 }
 
 pub fn (db DB) str() string {
@@ -63,7 +65,7 @@ fn C.sqlite3_errstr(int) charptr
 
 fn C.sqlite3_free(voidptr)
 
-// Opens the connection with a database.
+// connect Opens the connection with a database.
 pub fn connect(path string) ?DB {
 	db := &C.sqlite3(0)
 	if C.sqlite3_open(path.str, &db) != 0 {
@@ -71,9 +73,23 @@ pub fn connect(path string) ?DB {
 	}
 	return DB{
 		conn: db
+		is_open: true
 	}
 }
 
+// close Closes the DB.
+// TODO: For all functions, determine whether the connection is
+// closed first, and determine what to do if it is
+pub fn (mut db DB) close() ?bool {
+	code := C.sqlite3_close(db.conn)
+	if code == 0 {
+		db.is_open = false
+	} else {
+		return error('sqlite db error: failed to close with code: $code')
+	}
+	return true // successfully closed
+}
+
 // Only for V ORM
 fn (db DB) init_stmt(query string) &C.sqlite3_stmt {
 	stmt := &C.sqlite3_stmt(0)

vlib/sqlite/sqlite_test.v

@@ -4,9 +4,10 @@ fn test_sqlite() {
 	$if !linux {
 		return
 	}
-	db := sqlite.connect(':memory:') or {
+	mut db := sqlite.connect(':memory:') or {
 		panic(err)
 	}
+	assert db.is_open
 	db.exec('drop table if exists users')
 	db.exec("create table users (id integer primary key, name text default '');")
 	db.exec("insert into users (name) values ('Sam')")
@@ -25,4 +26,8 @@ fn test_sqlite() {
 		panic(err)
 	}
 	assert user.vals.len == 2
+	db.close() or {
+		panic(err)
+	}
+	assert !db.is_open
 }