PostgreSQL column does not exist when it does - postgresql

Question

I have the following PostgreSQL query...
WITH update_parts (id,id_finish)
AS (VALUES (1,42), (2,42), (3,30), (4,30))
UPDATE parts SET id = up.id, id_metal = up.id_metal
FROM update_parts up WHERE up.id = parts.id;
...and I get the error...
column up.id_metal does not exist LINE 1
I have verified I'm connected to the correct database, to the correct table and that the column exists. I'm only partially certain about permissions which I set via the following...
GRANT ALL(id_metal) ON parts TO public;
...and...
GRANT ALL(id_metal) ON parts TO postgres;
I plan to limit the permissions to SELECT, UPDATE, DELETE and INSERT after I've figured out the problem. For clarification it is the "parts" table and the "id_metal" column.
How do I resolve this error and UPDATE the rows?
After updating the permissions I'm not sure what else to consider?
I used the following query to get information about the column...
SELECT * FROM information_schema.columns
WHERE table_schema NOT IN ('pg_catalog', 'information_schema')
AND column_name='id_finish';
...which returns...
Array (
[table_catalog] => [database name]
[table_schema] => public
[table_name] => parts
[column_name] => id_metal
[ordinal_position] => 7
[column_default] =>
[is_nullable] => YES
[data_type] => bigint
[character_maximum_length] =>
[character_octet_length] =>
[numeric_precision] => 64
[numeric_precision_radix] => 2
[numeric_scale] => 0
[datetime_precision] =>
[interval_type] =>
[interval_precision] =>
[character_set_catalog] =>
[character_set_schema] =>
[character_set_name] =>
[collation_catalog] =>
[collation_schema] =>
[collation_name] =>
[domain_catalog] =>
[domain_schema] =>
[domain_name] =>
[udt_catalog] => [database name]
[udt_schema] => pg_catalog
[udt_name] => int8
[scope_catalog] =>
[scope_schema] =>
[scope_name] =>
[maximum_cardinality] =>
[dtd_identifier] => 7
[is_self_referencing] => NO
[is_identity] => NO
[identity_generation] =>
[identity_start] =>
[identity_increment] =>
[identity_maximum] =>
[identity_minimum] =>
[identity_cycle] =>
[is_generated] => NEVER
[generation_expression] =>
[is_updatable] => YES
)

Answer 1

You are going through a lot of hoops with permissions, but the problem is simple syntax:
WITH update_parts (id, id_finish) AS (
VALUES (1,42), (2,42), (3,30), (4,30)
)
UPDATE parts SET id_metal = up.id_finish
FROM update_parts up WHERE up.id = parts.id;
In your CTE you define the columns id and id_finish so your main query should refer to the same up.id_finish, not the id_metal from the parts table.
Further, it is usless to update parts.id with the value of update_parts.id because they are the same by definition: WHERE up.id = parts.id.