I'm using array_agg to group values into an array. The output for row is:
row: anonymous { values: '{(1),(2)}' }
I'm trying to then loop through the results in Node,
row.values.forEach(... but it says values.forEach is not a function, because typeof row.values is String.
I'm using array_agg, so why is the output a string, and how can I convert it to an array?
I just ran into this problem too and unnest wasn't an option due to needing a fixed number of rows to be returned and I couldn't guarantee my content wouldn't contain a , or brackets which made a regex solution challenging.
I found the best solution was to use json_agg instead of array_agg. (See the documentation) This returned the results in JSON format and node automatically interpreted it as a javascript object so you can use .forEach without any conversion needed.
Can convert an array to a set of rows by using: unnest
create temp table t (name text);
insert into t values ('name1'),('name2'),('name3'),('name4');
select unnest(array_agg(name)) as aname from t
+-------+
| aname |
+-------+
| name1 |
+-------+
| name2 |
+-------+
| name3 |
+-------+
| name4 |
+-------+
If you're expecting integers in the array, you can use regex and loop through the matches of (\d+).
Another method is to use array_to_string and have it join using values that do not appear in the content, a newline \n for example: array_to_string(some_array_content, E'\n'), then split it later.
Once you get it into an array one way or another, forEach will work.
Also, I believe Sequelize can handle arrays: http://docs.sequelizejs.com/en/v3/api/datatypes/#array
Dont know about knex, but for node-postgres, you can cast the results of array_agg to an array type, i.e. ::int[] and it will return an array instead of a string:
SELECT
array_agg(name)::int[],
foo_id
FROM bar
GROUP BY foo_id;
array_to_jsonto get something more readily parseable. (Not answering, because I don't know specifically about this driver.)