Support passing values to select(fields...) for insert into ... select from

[SadiinsoSnowfall]

The issue #1106 and then the PR #1496 added support for this kind of request :

INSERT INTO the_table (id, name, description)
    SELECT id + 1, name, description FROM the_table

Using this construct :

table! (
    the_table {
        id -> Integer,
        name -> Text,
        description -> Text,
    }
);

diesel::insert_into(the_table)
    .values(the_table.select(id + 1, name, description))
    .execute(conn);

However, it is not possible to re-create this following query using Diesel:

INSERT INTO the_table (id, name, description)
    SELECT 55, name, description FROM the_table

diesel::insert_into(the_table)
    .values(the_table.select(55, name, description))
    .execute(conn);

This rust code produce the following errors:

the trait bound `{integer}: diesel::Expression` is not satisfied
the trait bound `{integer}: SelectableExpression<the_table::table>` is not satisfied
the trait bound `{integer}: NonAggregate` is not satisfied

Would it be possible to support passing direct values to select(...) in order to support this kind of SQL query ?

[weiznich]

I've converted this to a discussion as this clearly is not a bug report and it does not follow the issue template (that's mandatory).
To answer this as question: Yes this is already possible. You need to convert the rust value explicitly to a diesel query builder expression. This can be done by for example calling IntoSql::into_sql().