SELECT on JSON operations of Postgres array column?

I have a column of type jsonb[] (a Postgres array of jsonb objects) and I’d like to perform a SELECT on rows where a criteria is met on at least one of the objects. Something like:

-- Schema would be something like
mytable (
  id UUID PRIMARY KEY,
  col2 jsonb[] NOT NULL
);

-- Query I'd like to run
SELECT
  id,
  x->>'field1' AS field1
FROM
  mytable
WHERE
  x->>'field2' = 'user' -- for any x in the array stored in col2

​x
 
-- Schema would be something likemytable (  id UUID PRIMARY KEY,  col2 jsonb[] NOT NULL);​-- Query I'd like to runSELECT  id,  x->>'field1' AS field1FROM  mytableWHERE  x->>'field2' = 'user' -- for any x in the array stored in col2​

I’ve looked around at ANY and UNNEST but it’s not totally clear how to achieve this, since you can’t run unnest in a WHERE clause. I also don’t know how I’d specify that I want the field1 from the matching object.

Do I need a WITH table with the values expanded to join against? And how would I achieve that and keep the id from the other column?

Thanks!

Answer

You need to unnest the array and then you can access each json value

SELECT t.id,
       c.x ->> 'field1' AS field1
FROM mytable t
  cross join unnest(col2) as c(x)
WHERE c.x ->> 'field2' = 'user'

 
SELECT t.id,       c.x ->> 'field1' AS field1FROM mytable t  cross join unnest(col2) as c(x)WHERE c.x ->> 'field2' = 'user' ​

This will return one row for each json value in the array.

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Answer