How i can use column_as for select alias table

[BlackSoulHub]

Hello all!

I need to get next model from query:

#[derive(FromQueryResult)]
pub struct EmailWithMailboxEntity {
    // fields of email. not interesting...
    id: i64,
    subject: String,
    content: String,
    date_time: DateTime<Utc>,
    
    // fields of mailboxes
    // sender fields
    sender_id: i64,
    sender_addr: String,
    // receiver fields
    receiver_id: i64,
    receiver_addr: String,
}

How i can do it?

I try this, but it isn't work:

email::Entity::find()
            // try to use aliases
            .column_as(Expr::col("t_receiver.id"), "receiver_id")
            .column_as(Expr::col("t_receiver.address"), "receiver_addr")
            .column_as(Expr::col("t_sender.id"), "sender_id")
            .column_as(Expr::col("t_sender.address"), "sender_addr")
            .join_as(
                // try to join table with alias `t_receiver`
                JoinType::LeftJoin,
                email::Entity::belongs_to(mailbox::Entity)
                    .from(email::Column::Receiver)
                    .to(mailbox::Column::Id)
                    .into(),
                Alias::new("t_receiver"),
            )
            .join_as(
                 // try to join table with alias `t_sender`
                JoinType::LeftJoin,
                email::Entity::belongs_to(mailbox::Entity)
                    .from(email::Column::Sender)
                    .to(mailbox::Column::Id)
                    .into(),
                Alias::new("t_sender"),
            )
            .filter(email::Column::OwnerMailbox.eq(owner_mbox_id))
            .offset(offset)
            .limit(limit);

In docs i find

Expr::col docs says: Express the target column without table prefix.

But i didn't find how i can create Expr with correct table prefix.

Maybe i can create create Column enum on fly?

I don't find decision in docs or examples.

[BlackSoulHub]

I found decision, but it's looks like bad.

I use idea from this comment: #802 (comment)

I create next struct:

struct Unquoted(String);

And implement Iden for this struct

impl Iden for Unquoted {
    fn unquoted(&self, s: &mut dyn Write) {
        // just write inner field to writer...
        write!(s, "{}", self.0).expect("Unquoted error")
    }
}

And create convenient API for this:

impl Unquoted {
    fn from_str(str: &str) -> DynIden {
        DynIden::new(Self(str.to_string()))
    }

    fn table_column(table: &str, column: &str) -> ColumnRef {
        ColumnRef::TableColumn(Unquoted::from_str(table), Unquoted::from_str(column))
    }
}

Usage:

email::Entity::find()
            .column_as(
                SimpleExpr::Column(Unquoted::table_column("t_receiver", "id")),
                "receiver_id",
            )
            .column_as(
                SimpleExpr::Column(Unquoted::table_column("t_receiver", "address")),
                "receiver_addr",
            )
            .column_as(
                SimpleExpr::Column(Unquoted::table_column("t_receiver", "role")),
                "receiver_role",
            )
            .column_as(
                SimpleExpr::Column(Unquoted::table_column("t_sender", "id")),
                "sender_id",
            )
            .column_as(
                SimpleExpr::Column(Unquoted::table_column("t_sender", "address")),
                "sender_addr",
            )
            .column_as(
                SimpleExpr::Column(Unquoted::table_column("t_sender", "role")),
                "sender_role",
            )
            .join_as(
                JoinType::LeftJoin,
                email::Entity::belongs_to(mailbox::Entity)
                    .from(email::Column::Receiver)
                    .to(mailbox::Column::Id)
                    .into(),
                Alias::new("t_receiver"),
            )
            .join_as(
                JoinType::LeftJoin,
                email::Entity::belongs_to(mailbox::Entity)
                    .from(email::Column::Sender)
                    .to(mailbox::Column::Id)
                    .into(),
                Alias::new("t_sender"),
            )
            .filter(email::Column::OwnerMailbox.eq(owner_mbox_id))
            .offset(offset)
            .limit(limit);

It works for me, but maybe there is a better way to do it?
Maybe i can to write PR to add new Expr::table_column(table: &str, column: &str)?