I want to group array of objects by its key,
The Original form;
data = [
{'id': 1, 'name': 'karthik'},
{'id': 1, 'age': 31},
{'id': 2, 'name': 'ramesh'},
{'id': 2, 'age': 22}
];
To transform in to,
groupedData = [
{'id': 1, 'name': 'karthik', 'age': 31},
{'id': 2, 'name': 'ramesh', 'age': 22}
];
What I tried,
this.data.map(item => item.id)
.filter((item, index, all) => all.indexOf(item) === index);
console.log(this.data);
Use reduce instead of map.
const groupedData = Object.values(this.data.reduce((a, { id, ...r }) => ({ ...a, [id]: { ...(a[id] || { id }), ...r }}), {}));
How this works:
Firstly, using reduce is far easier than any map solution because it allows us to have an accumulator value a.
Then, we extract the id, and the rest of the properties (because we don't know what they're called).
We return a, with the property keyed with the value of id being either the existing property or a new one with id, as well as the rest of the properties.
reduce to help you understand how the code works a little better.You can use reduce to create an object ( a table ) for each id.
const groupMap = data.reduce((group, currentData) => {
const id = currentData['id']
group[id] = { ...(group[id] || {}), ...currentData }
return group
} ,{})
what this returns is something like:
{
"1": {
"id": 1,
"name": "karthik",
"age": 31
},
"2": {
"id": 2,
"name": "ramesh",
"age": 22
}
}
group[id] = { ...(group[id] || {}), ...currentData } is basically "if you already saw this id, just merge the previous data with the current data"
then you can get the final result calling Object.values
const groupedData = Object.values(groupMap)
which just get the values of the object created above.
Try this
data = data.reduce((total, current, index) => {
for(let key in current) total[index][key] = current[key]
return total
}, [])
This function will help you)
function mergeobj(arrofobj) {
arrofobj.map((item, index) => {
for (let i = 0; i < arrofobj.length; i++) {
if(i==index)continue;
if (item['id'] == arrofobj[i]['id']) {
item = Object.assign(item, arrofobj[i]);
arrofobj.splice(i, 1);
--i;
}
}
return item;
})
return arrofobj; }