Proper way to convert SQL results to JSON - mysql

Question

I am creating a API using nodejs. The API takes request and responds in JSON
For example:
I have a table QUESTION in my database so a GET request to endpoint http://localhost/table/question will output the table in JSON format.
However there is a problem when performing JOINS
Considering tables QUESTION and CHOICE. A question has many choices (answers) their join will be
Table:
I am trying to convert to something like this
{
"0":{
"QUESTION":"If Size of integer pointer is 4 Bytes what is size of float pointer ?",
"OPTION":{
"A":"3 Bytes",
"B":"32 Bits",
"C":"64 Bits",
"D":"12 Bytes"
}
},
"1":{
"QUESTION":"Which one is not a SFR",
"OPTION":{
"A":"PC",
"B":"R1",
"C":"SBUF"
}
},
"2":{
"QUESTION":"What is Size of DPTR in 8051",
"OPTION":{
"A":"16 Bits",
"B":"8 Bytes",
"C":"8 Bits"
}
},
"3":{
"QUESTION":"Is to_string() is valid builtin function prior to c++11 ? ",
"OPTION":{
"A":"Yes",
"B":"No"
}
}
}
The obvious solution is to parse it query using JOIN and convert it to JSON.
Is there any more efficient way to do it?

Answer 1

In MySQL you can achieve this with group_concat
tablenames, fieldnames, etc are pure fantasy :-)
select
q.text as question,
group_concat(answer.label, ';;;') as labels,
group_concat(answer.text, ';;;') as answers
from
question as q
join answer as a on a.quesion = q.id
group by
q.text
And then in your application (nodejs)
let resultRows = callSomeFunctionsThatReturnesAllRowsAsArray();
let properStructure = resultRows.map(row => {
let texts = row.answers.split(';;;');
return {
question: row.question,
options: row.labels.split(';;;').map((label, index) => {label: label, answer: texts[index]});
}
});