orm: fix orm.Connection only allowing immutable Connections (#22684)

vlib/orm/orm.v

@@ -193,6 +193,7 @@ pub:
 // Every function without last_id() returns an optional, which returns an error if present
 // last_id returns the last inserted id of the db
 pub interface Connection {
+mut:
 	select(config SelectConfig, data QueryData, where QueryData) ![][]Primitive
 	insert(table string, data QueryData) !
 	update(table string, data QueryData, where QueryData) !

vlib/orm/orm_mut_connection_test.v

@@ -0,0 +1,109 @@
+// vtest flaky: true
+// vtest retry: 3
+import orm
+
+struct Database {
+mut:
+	last_query string
+}
+
+struct User {
+	id   int @[primary; sql: serial]
+	name string
+}
+
+fn (mut db Database) query(sql_stmt string) ! {
+	db.last_query = sql_stmt
+}
+
+// select is used internally by V's ORM for processing `SELECT` queries
+fn (mut db Database) select(config orm.SelectConfig, data orm.QueryData, where orm.QueryData) ![][]orm.Primitive {
+	// 1. Create query and bind necessary data
+	query := orm.orm_select_gen(config, '', true, ':', 1, where)
+	mut ret := [][]orm.Primitive{}
+	return ret
+}
+
+// insert is used internally by V's ORM for processing `INSERT` queries
+fn (mut db Database) insert(table string, data orm.QueryData) ! {
+	query, _ := orm.orm_stmt_gen(.sqlite, table, '', .insert, false, '?', 1, data, orm.QueryData{})
+
+	db.query(query)!
+}
+
+// update is used internally by V's ORM for processing `UPDATE` queries
+fn (mut db Database) update(table string, data orm.QueryData, where orm.QueryData) ! {
+	mut query, _ := orm.orm_stmt_gen(.sqlite, table, '', .update, true, ':', 1, data,
+		where)
+
+	db.query(query)!
+}
+
+// delete is used internally by V's ORM for processing `DELETE ` queries
+fn (mut db Database) delete(table string, where orm.QueryData) ! {
+	query, converted := orm.orm_stmt_gen(.sqlite, table, '', .delete, true, ':', 1, orm.QueryData{},
+		where)
+
+	db.query(query)!
+}
+
+// last_id is used internally by V's ORM for post-processing `INSERT` queries
+fn (mut db Database) last_id() int {
+	return 0
+}
+
+// DDL (table creation/destroying etc)
+fn sqlite_type_from_v(typ int) !string {
+	return if typ in orm.nums || typ in orm.num64 || typ in [orm.serial, orm.time_, orm.enum_] {
+		'INTEGER'
+	} else if typ in orm.float {
+		'REAL'
+	} else if typ == orm.type_string {
+		'TEXT'
+	} else {
+		error('Unknown type ${typ}')
+	}
+}
+
+// create is used internally by V's ORM for processing table creation queries (DDL)
+fn (mut db Database) create(table string, fields []orm.TableField) ! {
+	mut query := orm.orm_table_gen(table, '', true, 0, fields, sqlite_type_from_v, false) or {
+		return err
+	}
+	db.query(query)!
+}
+
+// drop is used internally by V's ORM for processing table destroying queries (DDL)
+fn (mut db Database) drop(table string) ! {
+	query := 'DROP TABLE ${table};'
+	$if trace_orm ? {
+		eprintln('> vsql drop: ${query}')
+	}
+	db.query(query)!
+}
+
+fn test_orm_mut_connection() {
+	mut db := Database{}
+
+	sql db {
+		create table User
+	}!
+
+	first_user := User{
+		name: 'first'
+	}
+	second_user := User{
+		name: 'second'
+	}
+
+	sql db {
+		insert first_user into User
+		insert second_user into User
+	}!
+
+	sql db {
+		drop table User
+	}!
+
+	assert db.last_query == 'DROP TABLE User;'
+}