How to select a Selectable with default values

[ISibboI]

I have a table like this:

CREATE TABLE job_queue (
    scheduled_time TIMESTAMPTZ NOT NULL,
    name TEXT NOT NULL,
    PRIMARY KEY (scheduled_time, name)
);

I would like to create a Selectable for this table that automatically populates one field with CURRENT_TIMESTAMP(), like this:

#[derive(Insertable, Queryable, Selectable, Identifiable, AsChangeset, Clone, Debug)]
#[diesel(table_name = crate::schema::job_queue)]
#[diesel(primary_key(scheduled_time, name))]
#[diesel(check_for_backend(diesel::pg::Pg))]
pub struct InProgressJob {
    scheduled_time: DateTime<Utc>,
    start_time: DateTime<Utc>,
    name: String,
}

How do I use this as the return type of the following SQL, such that start_time will be the result of calling NOW()?

SELECT (scheduled_time, NOW(), name) FROM job_queue LIMIT 10;

[weiznich]

See the last example in the documentation. The expression can be freely chosen. The type must match the expression.

[ISibboI]

Not sure if I have time for that, but would you accept a pull request explaining this use case in the docs? So far it refers only to "flattening of fields"

[ISibboI]

I just opened a pull request #3751