I expected Rails' `joins` method to accept an array with a string and variable arguments, as I'm used to with `where`:

```
my_var = 42
Topic.where(["id = ?", my_var])

```

However, that doesn't work for `joins`:

```
Topic.joins(["LEFT JOIN `wave` ON `wave`.`obj_id` = ?", my_var])

```

How can I achieve the same (a string where the question marks will be replaced with sanitized variables) for the `joins` operation?