Source contract and expected records
This is an original, fully synthetic mapping example. Inputs are plain, acyclic JSON-shaped records with the fields shown; the canonical shape and rejection codes belong to this example. Adapt the contract before using a different source.
Questions declare unique nonempty keys, kinds text/integer/boolean and Boolean required flags. Reject unknown answer keys, missing required answers and mismatched values. Text must not be all whitespace; integer means safe whole number; false and zero are valid. Preserve typed answers in question order and list absent optional keys as unanswered.
| Case | Input record (JSON) | Expected output (JSON) |
|---|---|---|
| Construct typed answers | {"questions":[{"key":"name","kind":"text","required":true},{"key":"count","kind":"integer","required":false}],"answers":{"name":"Ada","count":0}} | {"ok":true,"value":{"answers":[{"key":"name","kind":"text","value":"Ada"},{"key":"count","kind":"integer","value":0}],"unanswered":[]}} |
| Reject missing required answer | {"questions":[{"key":"name","kind":"text","required":true}],"answers":{}} | {"ok":false,"error":"ANSWER_REQUIRED"} |
| Preserve absent optional answer | {"questions":[{"key":"name","kind":"text","required":true},{"key":"count","kind":"integer","required":false}],"answers":{"name":"Ada"}} | {"ok":true,"value":{"answers":[{"key":"name","kind":"text","value":"Ada"}],"unanswered":["count"]}} |
Run the local transformation
Run the complete example as a JavaScript module in Node.js. It contains the pure mapping function, all three inputs and literal expected outputs; assertions stop on a mismatch. A rejected case returns ok=false with an error code, rather than a partial canonical record.
import assert from 'node:assert/strict';
function questionnaireAnswers(i){
const fail=error=>({ok:false,error});if(!i||!Array.isArray(i.questions)||!i.answers||typeof i.answers!=='object'||Array.isArray(i.answers))return fail('ANSWER_SHAPE');
const keys=new Set(),answers=[],unanswered=[];
for(const q of i.questions){if(!q||typeof q.key!=='string'||!q.key||keys.has(q.key)||!['text','integer','boolean'].includes(q.kind)||typeof q.required!=='boolean')return fail('QUESTION_DEFINITION');keys.add(q.key);}
if(Object.keys(i.answers).some(k=>!keys.has(k)))return fail('ANSWER_UNKNOWN');
for(const q of i.questions){
if(!Object.hasOwn(i.answers,q.key)){if(q.required)return fail('ANSWER_REQUIRED');unanswered.push(q.key);continue;}
const v=i.answers[q.key];const valid=q.kind==='text'?typeof v==='string'&&!!v.trim():q.kind==='integer'?Number.isSafeInteger(v):typeof v==='boolean';
if(!valid)return fail('ANSWER_TYPE');answers.push({key:q.key,kind:q.kind,value:v});
}
return {ok:true,value:{answers,unanswered}};
}
// Original synthetic cases; expected outputs are literal records.
const cases = [
{
"label": "Construct typed answers",
"input": {
"questions": [
{
"key": "name",
"kind": "text",
"required": true
},
{
"key": "count",
"kind": "integer",
"required": false
}
],
"answers": {
"name": "Ada",
"count": 0
}
},
"expected": {
"ok": true,
"value": {
"answers": [
{
"key": "name",
"kind": "text",
"value": "Ada"
},
{
"key": "count",
"kind": "integer",
"value": 0
}
],
"unanswered": []
}
}
},
{
"label": "Reject missing required answer",
"input": {
"questions": [
{
"key": "name",
"kind": "text",
"required": true
}
],
"answers": {}
},
"expected": {
"ok": false,
"error": "ANSWER_REQUIRED"
}
},
{
"label": "Preserve absent optional answer",
"input": {
"questions": [
{
"key": "name",
"kind": "text",
"required": true
},
{
"key": "count",
"kind": "integer",
"required": false
}
],
"answers": {
"name": "Ada"
}
},
"expected": {
"ok": true,
"value": {
"answers": [
{
"key": "name",
"kind": "text",
"value": "Ada"
}
],
"unanswered": [
"count"
]
}
}
}
];
for (const sample of cases) {
const actual = questionnaireAnswers(sample.input);
assert.deepEqual(actual, sample.expected);
console.log(sample.label, JSON.stringify(actual));
}
Work through the boundary
How does optional count=0 differ from an omitted count?
Show the worked answer
Zero produces a typed integer answer. Omission puts count in unanswered with no count answer record. A missing required name returns ANSWER_REQUIRED instead of an empty default.