To get list of columns with transformation formula about pglast HOT 3 CLOSED

The following script does that:

from pglast.parser import parse_sql
from pglast.stream import RawStream
from pglast.visitors import Visitor


class TargetColumnNames(Visitor):
    def __call__(self, node):
        self.tcnames = {}
        super().__call__(node)
        return self.tcnames

    def visit_ResTarget(self, ancestors, node):
        self.tcnames[node.name] = RawStream()(node.val)


def target_columns(stmt):
    return TargetColumnNames()(parse_sql(stmt) if isinstance(stmt, str) else stmt)


print(target_columns("SELECT t1.name AS name, t1.name||' '||t2.name AS new_name"
                     " FROM t1 inner join t2 on t1.id = t2.par_id"))

As always, details matter, and your problem is to define more clear rules that describe what you mean with "list of columns": for example, what should happen if the statement has subselects?

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Thanks @lelit , that's really cool! thanks!
Regarding your comment, yes you are right, need to get a ETL transformation for every column, and SQL can contain several ETLs for one column (like CTE , subqueries~subselects).
So, currently, I am going to work on your code to get a branch of transformation for one column

from pglast.

I think there's nothing more to be done here, right? Otherwise, feel free to reopen the issue!

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