Array of structures vs structure of arrays in JSON - json

Question

Let I have an array of structures in JSON like this:
[{
"name": "Amrit",
"second_name": "Valentine"
},
{
"name": "Beatriz",
"second_name": "Carty"
}// And so on...
]
It is human readable, but the issue with it is that "name" and "second_name" are repeated for all entities in this array. And if the array is big, it creates about 40% size overhead.
On the other hand, I could translate this data structure:
{
"names": ["Amrit", "Beatriz" /* ... */],
"second_names": ["Valentine", "Carty" /* ... */]
}
But it is not human readable any longer, but the size is optimal. It is also error prone, since it is not guaranteed that sizes of "names" and "second_names" are the same.
Is there any trade-off in JSON, so I can use array of structures without repeating filed names and the size is still optimal?

Answer 1

Not as part of JSON itself, no. What I've done on projects is a generic system where the JSON would look like this:
{
"__keys__": ["name", "second_name"],
"values": [
["Amrit", "Valentine"],
["Beatriz", "Carty"]
]
}
...where once I've parsed the JSON, I throw a utility function at it to consume that and turn it into an array of objects. Along these lines:
const json = `{
"__keys__": ["name", "second_name"],
"values": [
["Amrit", "Valentine"],
["Beatriz", "Carty"]
]
}`;
const parsed = JSON.parse(json);
const expanded = expand(parsed);
console.log(expanded);
function expand(data) {
const keys = data.__keys__;
return data.values.map(entry => {
const obj = {};
keys.forEach((key, index) => {
obj[key] = entry[index];
});
return obj;
});
}
Or, of course, you just leave off __keys__ and assume your endpoint knows what the keys should be, but it impairs readability/debugging even more than the above does. :-)
(You can shoehorn that forEach into a reduce, because you can shoehorn just about any array operation into a reduce, but it doesn't buy you anything.)