I have two tables that I want to retrieve values from using a LEFT JOIN. Diesel wants to handle any values from the joined table as nullable (which is sensible, given that there may or may not be a record), and it surfaces this in Rust using Option<T>.

I want my struct to contain a T, and if the corresponding record is absent, use T::default(). So, essentially, I just want the final type to get an .unwrap_or_default at the end.

In other words, instead of…

struct MyStuff {
  left_table_data: String,
  right_table_data: Option<String>,
}

I want…

struct MyStuff {
  left_table_data: String,
  #[diesel(deserialize_as = Option<String>, ...)]  // something to make diesel call `unwrap_or_default`
  right_table_data: String,
}

Is there a way to do this within the Diesel API, without manually coding an intermediate struct or similar?