Extracting a string from a nested dictionary in presto

I have data that looks like this:

WITH raw_string AS (
    
    SELECT '{
        "484934206380132":["__time__":"1657740233","__qtype__":"message"]
        ,"492645072399511":{"__time__":"1657740228","__qtype__":"text"}
        ,"386574019969974":{"__time__":"1657740228","__qtype__":"text"}
        ,"1043183892945050":{"__time__":"1657740228","subquestions":"["Kick-off call","Creative presentation","Design Sessions","Final deliverables (assets)"]","__qtype__":"ratingmatrix"}
        ,"3184511478430353":{"__time__":"1657740228","subquestions":"["Making ads for Meta platforms","Producing video content","Applying mobile creative best practices"]","__qtype__":"ratingmatrix"}
        ,"1115358562640462":{"__time__":"1657740228","__qtype__":"radio"}
        ,"392599788967548":{"__time__":"1657740228","__qtype__":"dropdown"}
        ,"318278303702075":{"__time__":"1657740228","translation":"07132022","__qtype__":"numeric_field"},"2629866570491655":{"__time__":"1657740228","__qtype__":"checkbox"}
        ,"481522393704422":{"__time__":"1657740228","translation":"Total Bet","__qtype__":"text"}
        ,"1091749101368816":{"__time__":"1657740228","translation":"The collaborative work","__qtype__":"text"}
        ,"503986774424936":{"__time__":"1657740228","__qtype__":"text"}
        }' AS question_context
) 

SELECT * FROM raw_string

I’d like to extract “subquestions” into separate rows (in an sql table): — Making ads for Meta platforms — Producing video content — Applying mobile creatives best…

I have a tried a few functions json_extract_scalar, and Map functions etc, but I didn’t succeed.

Thanks in advance for your help.

So the thing I was doing, which is a bit convoluted and leads to an incorrect solution is this:

WITH raw_string AS (
    
    SELECT *
    FROM
     (VALUES ('{
        "484934206380132":["__time__":"1657740233","__qtype__":"message"]
        ,"492645072399511":{"__time__":"1657740228","__qtype__":"text"}
        ,"386574019969974":{"__time__":"1657740228","__qtype__":"text"}
        ,"1043183892945050":{"__time__":"1657740228","subquestions":"["Kick-off call","Creative presentation","Design Sessions","Final deliverables (assets)"]","__qtype__":"ratingmatrix"}
        ,"3184511478430353":{"__time__":"1657740228","subquestions":"["Making ads for Meta platforms","Producing video content","Applying mobile creative best practices"]","__qtype__":"ratingmatrix"}
        ,"1115358562640462":{"__time__":"1657740228","__qtype__":"radio"}
        ,"392599788967548":{"__time__":"1657740228","__qtype__":"dropdown"}
        ,"318278303702075":{"__time__":"1657740228","translation":"07132022","__qtype__":"numeric_field"},"2629866570491655":{"__time__":"1657740228","__qtype__":"checkbox"}
        ,"481522393704422":{"__time__":"1657740228","translation":"Total Bet","__qtype__":"text"}
        ,"1091749101368816":{"__time__":"1657740228","translation":"The collaborative work","__qtype__":"text"}
        ,"503986774424936":{"__time__":"1657740228","__qtype__":"text"}
        }')) AS question_cntxt(questions_context)
) 

SELECT * FROM (
    SELECT * FROM (
    SELECT * FROM raw_string
    CROSS JOIN UNNEST(questions_context) AS t(qn_id, sub_qn)
)
CROSS JOIN UNNEST(sub_qn) as t(category, _values)
)
CROSS JOIN UNNEST(SPLIT(_values, ',')) AS t(_levels)

I come close to what am trying to do, but I end up with a lot more rows than I need. I think I’m getting closer though.

The thing am really trying to do is put together a datasets of questions and answers. I want to pair them up together nicely.

The data looks like this::

    
    SELECT *
    FROM
     (VALUES ('{
        "484934206380132":["__time__":"1657740233","__qtype__":"message"]
        ,"492645072399511":{"__time__":"1657740228","__qtype__":"text"}
        ,"386574019969974":{"__time__":"1657740228","__qtype__":"text"}
        ,"1043183892945050":{"__time__":"1657740228","subquestions":"["Kick-off call","Creative presentation","Design Sessions","Final deliverables (assets)"]","__qtype__":"ratingmatrix"}
        ,"3184511478430353":{"__time__":"1657740228","subquestions":"["Making ads for Meta platforms","Producing video content","Applying mobile creative best practices"]","__qtype__":"ratingmatrix"}
        ,"1115358562640462":{"__time__":"1657740228","__qtype__":"radio"}
        ,"392599788967548":{"__time__":"1657740228","__qtype__":"dropdown"}
        ,"318278303702075":{"__time__":"1657740228","translation":"07132022","__qtype__":"numeric_field"},"2629866570491655":{"__time__":"1657740228","__qtype__":"checkbox"}
        ,"481522393704422":{"__time__":"1657740228","translation":"Total Bet","__qtype__":"text"}
        ,"1091749101368816":{"__time__":"1657740228","translation":"The collaborative work","__qtype__":"text"}
        ,"503986774424936":{"__time__":"1657740228","__qtype__":"text"}
        }', 
        '{"1043183892945050":["Very satisfied","Very satisfied","Very satisfied","Very satisfied"]
        ,"1091749101368816":["All participants are engaging and open to feedback. The agency is ready to accept suggestions and proactively suggest ideas as well."]
        ,"1115358562640462":["5 - Very Satisfied"],"2629866570491655":["Yes",null,null]
        ,"318278303702075":["07122022"]
        ,"3184511478430353":["Somewhat confident","Somewhat confident","Somewhat confident"]
        ,"386574019969974":["NA"],"392599788967548":["Asia Pacific (APAC)"],"481522393704422":["Genero"]
        }'
        )) AS question_cntxt(questions, answers)
) 

SELECT * FROM raw_string

I want to create a table where in the end I have a question:

|qn_id           | category.           |Answer          |
|----------------|---------------------|----------------|
|1043183892945050|Kick-off call.       | Very Satisfied.|
|1043183892945050|Creative presentation| Very satisfied |
|1043183892945050|Design sessions.     | Very satisfied |
|1043183892945050|Final deri.          | very sat.      |

I was trying to take a shot at it one column at a time

Answer

After fixing the json (the first property for some reason contains mailformed array, not another json object), you can do next:

WITH raw_string AS (
    
    SELECT '{
        "484934206380132":{"__time__":"1657740233","__qtype__":"message"}
        ,"492645072399511":{"__time__":"1657740228","__qtype__":"text"}
        ,"386574019969974":{"__time__":"1657740228","__qtype__":"text"}
        ,"1043183892945050":{"__time__":"1657740228","subquestions":"["Kick-off call","Creative presentation","Design Sessions","Final deliverables (assets)"]","__qtype__":"ratingmatrix"}
        ,"3184511478430353":{"__time__":"1657740228","subquestions":"["Making ads for Meta platforms","Producing video content","Applying mobile creative best practices"]","__qtype__":"ratingmatrix"}
        ,"1115358562640462":{"__time__":"1657740228","__qtype__":"radio"}
        ,"392599788967548":{"__time__":"1657740228","__qtype__":"dropdown"}
        ,"318278303702075":{"__time__":"1657740228","translation":"07132022","__qtype__":"numeric_field"},"2629866570491655":{"__time__":"1657740228","__qtype__":"checkbox"}
        ,"481522393704422":{"__time__":"1657740228","translation":"Total Bet","__qtype__":"text"}
        ,"1091749101368816":{"__time__":"1657740228","translation":"The collaborative work","__qtype__":"text"}
        ,"503986774424936":{"__time__":"1657740228","__qtype__":"text"}
        }' AS question_context
) 

SELECT subquestion
FROM (
    SELECT map_values( -- get values which is in turn array of maps
        map_filter( -- get only records with subquestions
            cast(json_parse(question_context) as map(varchar, map(varchar, varchar))),
            (k, v)->element_at(v, 'subquestions') is not null
        )
    ) mp_arr
    FROM raw_string
) p
, unnest(mp_arr) as t(mp) -- unnest array of maps
, unnest(cast(json_parse(mp['subquestions']) as array(varchar))) as tt(subquestion) -- 'subquestions' are double encoded so need to decode them

Output:

subquestion
Kick-off call
Creative presentation
Design Sessions
Final deliverables (assets)
Making ads for Meta platforms
Producing video content
Applying mobile creative best practices

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Answer