I have the following array of objects:
[
{
message: 'This is a test',
from_user_id: 123,
to_user_id: 567
},
{
message: 'Another test.',
from_user_id: 123,
to_user_id: 567
},
{
message: 'A third test.',
from_user_id: '456',
to_user_id: 567
}
]
How do I construct a new array of objects where the outermost object key is based on a mon key found in the original array?
This is what I'm after:
[
{
123: [
{
message: 'This is a test',
from_user_id: 123,
to_user_id: 567
},
{
message: 'Another test.',
from_user_id: 123,
to_user_id: 567
}
]
},
{
456: [
{
message: 'A third test.',
from_user_id: '456',
to_user_id: 567
}
]
}
]
Notice how in the first array, the user ID of 123 shows up in two objects. That would be the object key for the first element in the new array.
I have the following array of objects:
[
{
message: 'This is a test',
from_user_id: 123,
to_user_id: 567
},
{
message: 'Another test.',
from_user_id: 123,
to_user_id: 567
},
{
message: 'A third test.',
from_user_id: '456',
to_user_id: 567
}
]
How do I construct a new array of objects where the outermost object key is based on a mon key found in the original array?
This is what I'm after:
[
{
123: [
{
message: 'This is a test',
from_user_id: 123,
to_user_id: 567
},
{
message: 'Another test.',
from_user_id: 123,
to_user_id: 567
}
]
},
{
456: [
{
message: 'A third test.',
from_user_id: '456',
to_user_id: 567
}
]
}
]
Notice how in the first array, the user ID of 123 shows up in two objects. That would be the object key for the first element in the new array.
4 Answers
Reset to default 5You could use an object and take the from_user_id property as key for the object. Then push the actual object to the group. For getting the final result, iterate the keys of groups and build a new object for any group.
var data = [{ message: 'This is a test', from_user_id: 123, to_user_id: 567 }, { message: 'Another test.', from_user_id: 123, to_user_id: 567 }, { message: 'A third test.', from_user_id: '456', to_user_id: 567 }],
groups = Object.create(null),
result;
data.forEach(function (a) {
groups[a.from_user_id] = groups[a.from_user_id] || [];
groups[a.from_user_id].push(a);
});
result = Object.keys(groups).map(function (k) {
var temp = {};
temp[k] = groups[k];
return temp;
});
console.log(result);.as-console-wrapper { max-height: 100% !important; top: 0; }Together with a single loop approach
var data = [{ message: 'This is a test', from_user_id: 123, to_user_id: 567 }, { message: 'Another test.', from_user_id: 123, to_user_id: 567 }, { message: 'A third test.', from_user_id: '456', to_user_id: 567 }],
result = data.reduce(function (groups) {
return function (r, a) {
var temp = {};
if (!groups[a.from_user_id]) {
groups[a.from_user_id] = [];
temp[a.from_user_id] = groups[a.from_user_id];
r.push(temp);
}
groups[a.from_user_id].push(a);
return r;
};
}(Object.create(null)), []);
console.log(result);.as-console-wrapper { max-height: 100% !important; top: 0; }You could go full functional get all the key filter it out and map it back as a json object
var b = a.map(key => key['from_user_id'])
var c = {}
b.map(elt => c[elt] = a.filter(k => k.from_user_id == elt))
console.log(c)
You just need to initialize a results array, loop over your data array and check if the iterated from_user_id exists in the results array, push the iterated object on it, otherwise create a new object with the new from_user_id key.
This is how should be your code:
var results = [];
arr.forEach(function(obj){
let id = obj["from_user_id"];
if(!results.some(function(r){
return r[id];
})){
let el = {};
el[id] = [];
el[id].push(obj);
results.push(el);
}else{
results.forEach(function(res){
if(res[id]){
res[id].push(obj);
}
});
}
});
Demo:
var arr = [{
message: 'This is a test',
from_user_id: 123,
to_user_id: 567
}, {
message: 'Another test.',
from_user_id: 123,
to_user_id: 567
}, {
message: 'A third test.',
from_user_id: 456,
to_user_id: 567
}];
var results = [];
arr.forEach(function(obj){
let id = obj["from_user_id"];
if(!results.some(function(r){
return r[id];
})){
let el = {};
el[id] = [];
el[id].push(obj);
results.push(el);
}else{
results.forEach(function(res){
if(res[id]){
res[id].push(obj);
}
});
}
});
console.log(results);
var users = [
{
message: 'This is a test',
from_user_id: 123,
to_user_id: 567
},
{
message: 'Another test.',
from_user_id: 123,
to_user_id: 567
},
{
message: 'A third test.',
from_user_id: '456',
to_user_id: 567
}
];
console.log(_.groupBy(users,'from_user_id'))<script src="https://cdnjs.cloudflare./ajax/libs/lodash.js/4.17.4/lodash.min.js"></script>Using Lodash will make it super easy for you. Assuming you have :
var users = [
{
message: 'This is a test',
from_user_id: 123,
to_user_id: 567
},
{
message: 'Another test.',
from_user_id: 123,
to_user_id: 567
},
{
message: 'A third test.',
from_user_id: '456',
to_user_id: 567
}
];
just in one line with Lodash and you'll get want you want exactly:
users = _.groupBy(users,'from_user_id')