Javascript: merge cartesian array of objects

Question

I have below array of objects

{
 "roleid":[{"rolename":[1639]}],
 "modnameid":[{"mname":[1516,1515,1514]}],
 "accesstype":[{"accesstype":["VO","AA"]}]
}

and I want to convert it format below

[
{"modnameid":1516,"accesstype":"VO","roleid":1639},
{"modnameid":1516,"accesstype":"AA","roleid":1639},
{"modnameid":1515,"accesstype":"VO","roleid":1639},
{"modnameid":1515,"accesstype":"AA","roleid":1639},
{"modnameid":1514,"accesstype":"VO","roleid":1639},
{"modnameid":1514,"accesstype":"AA","roleid":1639}
]

How do we go about it, basic assumption what multi-tier map based operation, food for thoughts Assistance is appreciated!

Sorry, you need to try it yourself first. Please show your attempt and explain exactly where you're stuck and where the code you wrote isn't behaving as intended. Try some `.forEach()`, some `.map()`, then we'll see where you're stuck. — Jeremy Thille, Feb 02 '21 at 12:55
https://stackoverflow.com/questions/12303989/cartesian-product-of-multiple-arrays-in-javascript seems like a good start. Some other options at https://stackoverflow.com/search?q=%5Bjavascript%5D+cartesian . Good luck! — malarres, Feb 02 '21 at 12:58
@malarres yeah gone through those link they seems to applicable on arrays not object array thanks again for links tho ! cheers ! — Rizwan Patel, Feb 02 '21 at 13:05

score 1 · Answer 1 · answered Feb 02 '21 at 13:10

can user

let data = {
    "roleid": [{ "rolename": [1639] }],
    "modnameid": [{ "mname": [1516, 1515, 1514] }],
    "accesstype": [{ "accesstype": ["VO", "AA"] }]
}
let roles = []
data.roleid.forEach(element => {
    roles = [...roles, ...element.rolename]
});

let names = []
data.modnameid.forEach(element => {
    names = [...names, ...element.mname]
});

let types = []
data.accesstype.forEach(element => {
    types = [...types, ...element.accesstype]
});

let informations = []
roles.forEach(role => {
    names.forEach(name => {
        types.forEach(type => {
            informations.push({ "modnameid": role, "accesstype": type, "roleid": name })
        });
    });
});

console.log(informations);

score 1 · Accepted Answer · answered Feb 02 '21 at 13:24

Beside the hardcoded answer, you could take a dynamic approach and get first an object with flat arrays of data and build an array of the cartesian product.

function getCartesian(object) {
    return Object.entries(object).reduce((r, [k, v]) => {
        var temp = [];
        r.forEach(s =>
            (Array.isArray(v) ? v : [v]).forEach(w =>
                (w && typeof w === 'object' ? getCartesian(w) : [w]).forEach(x =>
                    temp.push(Object.assign({}, s, { [k]: x }))
                )
            )
        );
        return temp;
    }, [{}]);
}

const
    data = { roleid: [{ rolename: [1639] }], modnameid: [{ mname: [1516, 1515, 1514] }], accesstype: [{ accesstype: ["VO", "AA"] }] },
    flat = v => v && typeof v === 'object'
        ? Object.values(v).flatMap(flat)
        : v;
    temp = Object.fromEntries(Object.entries(data).map(([k, v]) => [k, flat(v)]));

console.log(temp);
console.log(getCartesian(temp));

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Javascript: merge cartesian array of objects

2 Answers2