AngularJS/Angular 2: Restructure the json after getting 'http' response - angularjs

Question

Current:
[{
"name": "a1",
"category": "C1",
"amount": 10
},
{
"name": "a3",
"category": "C1",
"amount": 30
},
{
"name": "a2",
"category": "C1",
"amount": 20
},
{
"name": "a1",
"category": "C2",
"amount": 100
},
{
"name": "a6",
"category": "C2",
"amount": 600
},
{
"name": "a2",
"category": "C2",
"amount": 200
},
{
"name": "a5",
"category": "C2",
"amount": 500
},
{
"name": "a1",
"category": "C3",
"amount": 1000
},
{
"name": "a3",
"category": "C3",
"amount": 3000
},
{
"name": "a5",
"category": "C3",
"amount": 5000
}
]
convert to:
[
{
"name": "a1",
"C1": 10,
"C2": 100,
"C3": 1000
},
{
"name": "a2",
"C1": 20,
"C2": 200,
"C3": -
},
{
"name": "a3",
"C1": 30,
"C2": -,
"C3": 3000
},
{
"name": "a5",
"C1": -,
"C2": 500,
"C3": 5000
},
{
"name": "a6",
"C1": -,
"C2": 600,
"C3": -
}
]

Answer 1

If you want only the properties that have been passed in (e.g. if there is no C2 for a1, then the mapped a1 will not have a C2 property):
var response = {} //set this equal to your original response, rather than an empty object
var list = {}
var mappedResponse = [];
let mapResponse = () => {
response.forEach(item => {
current = list[item.name] || {};
current.name = item.name;
current[item.category] = item.amount;
list[item.name] = current;
});
Object.keys(list).forEach(key => {
mappedResponse.push(list[key]);
});
return mappedResponse;
}
mapResponse();
If you wanted to explicitly declare something like null for those empty fields, rather than having them be undefined, you could change the forEach to look like this:
response.forEach(item => {
current = list[item.name] || {};
current.name = item.name;
current['C1'] = item.category === 'C1' ? item.amount : current['C1'] || null;
current['C2'] = item.category === 'C2' ? item.amount : current['C2'] || null;
current['C3'] = item.category === 'C3' ? item.amount : current['C3'] || null;
list[item.name] = current;
});

Answer 2

Here is my version!
Please not the output JSON you wanted contains the below line.
"C3": -
I checked whether the JSON is valid or not on JSONLint.com and I got the below error.
Error: Parse error on line 14: ... "C2": 200, "C3": - }, { "name":
----------------------^ Expecting 'STRING', 'NUMBER', 'NULL', 'TRUE', 'FALSE', '{', '[', got 'undefined'
This will make the JSON invalid. So what is suggest is to leave out this property! Please let me know if that is fine?
//starting JSON
var json = [{
"name": "a1",
"category": "C1",
"amount": 10
},
{
"name": "a3",
"category": "C1",
"amount": 30
},
{
"name": "a2",
"category": "C1",
"amount": 20
},
{
"name": "a1",
"category": "C2",
"amount": 100
},
{
"name": "a6",
"category": "C2",
"amount": 600
},
{
"name": "a2",
"category": "C2",
"amount": 200
},
{
"name": "a5",
"category": "C2",
"amount": 500
},
{
"name": "a1",
"category": "C3",
"amount": 1000
},
{
"name": "a3",
"category": "C3",
"amount": 3000
},
{
"name": "a5",
"category": "C3",
"amount": 5000
}
]
var out=[];
var final = [];
//code used to filter out the unique names ["a1", "a2", etc]
for (let a of json){
if(out.indexOf(a.name) === -1){
out.push(a.name);
}
}
//loop through the unique names!
for (let a of out){
var obj = {};
//filter the object for a particular name
for(let j of json.filter(function(x){return x.name===a})){
//merge the objects `category` and `amount` as a object
Object.assign(obj, {[j.category]: j.amount});
}
//finally push it to the final list that is `final`
var temp = {name: a};
Object.assign(temp, obj);
final.push(temp);
}
//console.log the output
console.log(final);