How to get a postgresql query result as JSON - sql

Question

I have text field in a table and I want query this field using where a condition: I want to query all records that has at least one word from as list of words and returns a JSON like this:
text
The employee was fired today
He likes chocolate a lot
She eat chocolate today
Car was stolen yesterday
select * from tbl
where text CONTAINS ANY ['today','likes','eat']
Desidered Output 1:
{"id":"1", "text":"The employee was fired today", "tag":"today"}
{"id":"2", "text":"He likes chocolate a lot", "tag":"likes"}
{"id":"3", "text":"She eat chocolate today", "tag":["today","eat"]}
Desidered Output 2:
text tag tag_counts
The employee was fired today today 1
He likes chocolate a lot likes 1
She eat chocolate today eat, today 2
I would like to get any of these outputs.
I already found that I can use WHERE IN ('today','likes','eat') but I can't find out how to get the result in any of the desired output, if possible.

Answer 1

I chose the column name words for the text column. "text" is a basic type name and too confusing as such.
For your given table with a plain text column:
SELECT *
FROM tbl t
, LATERAL (
SELECT string_agg(tag, ', ') AS tags, count(*) AS tag_count
FROM (
SELECT unnest(string_to_array(words, ' ')) tag
INTERSECT ALL
SELECT unnest ('{today, likes, eat}'::text[])
) i
) ct
WHERE string_to_array(t.words, ' ') && '{today, likes, eat}';
Simpler with a text array (text[]) in the table to begin with:
SELECT *
FROM tbl1 t
, LATERAL (
SELECT string_agg(tag, ', ') AS tags, count(*) AS tag_count
FROM (
SELECT unnest(words) tag
INTERSECT ALL
SELECT unnest ('{today, likes, eat}'::text[])
) i
) ct
WHERE t.words && '{today, likes, eat}';
db<>fiddle here
Can be supported with a GIN index. An expression index for the text column:
CREATE INDEX tbl_words_gin_idx ON tbl USING gin (string_to_array(words, ' '));
Simpler, yet again, for text[]:
CREATE INDEX tbl1_words_gin_idx ON tbl1 USING gin (words);
See:
Query and order by number of matches in JSON array