json_agg 的 PSQL 动态键值

Question

I have this table structure:

I'm grouping every element into an array based on the name column:

SELECT json_agg(json_build_object(
  'id', id,
  'time', time,
  'version', version,
  'desc1', 'desc1',
  'desc2', 'desc2',
 ))
FROM my_table
GROUP BY name

which gives me this result:

[ { json_agg: [ [Object] ] }, { json_agg: [ [Object] ] } ]

how ever I want the json_agg key to be the same as the name column value. like this:

[ { test1: [ [Object] ] }, { test2: [ [Object] ] } ]

How do I achieve this? Using an AS name doesn't work.

Answer 1

For each grouping, you to build a new object using name and the aggregated array result in a subquery. Then aggregate the objects created in that subquery into a single array.

SELECT
  json_agg(elem) arr
FROM

(
SELECT
    json_build_object(
      name,
      json_agg(json_build_object(
        'id', id,
        'time', time,
        'version', version,
        'desc1', 'desc1',
        'desc2', 'desc2',
      ))
    ) elem

FROM
 my_table

GROUP BY
  name
) elem