Function resolve_columns

datafusion/sql/src/utils.rs:45–63

Make a best-effort attempt at resolving all columns in the expression tree

(expr: &Expr, plan: &LogicalPlan)

/// Make a best-effort attempt at resolving all columns in the expression tree
pub(crate) fn resolve_columns(expr: &Expr, plan: &LogicalPlan) -> Result<Expr> {
    expr.clone()
        .transform_up(|nested_expr| {
            match nested_expr {
                Expr::Column(col) => {
                    let (qualifier, field) =
                        plan.schema().qualified_field_from_column(&col)?;
                    Ok(Transformed::yes(Expr::Column(Column::from((
                        qualifier, field,
                    )))))
                }
                _ => {
                    // keep recursing
                    Ok(Transformed::no(nested_expr))
                }
            }
        })
        .data()
}

/// Rebuilds an `Expr` as a projection on top of a collection of `Expr`'s.
///