Angular 2 (Typescript) - RxJS observable - groupBy

Question

json data,

{
 "name": "Sam",
 "age":25,
 "schools":
 [
     {
       "country":"USA",
       "state":"IN",
       "city":"Fishers",
       "name":"school 1"
     },
     {
       "country":"USA",
       "state":"IN",
       "city":"Indianapolis",
       "name":"school 2"
     },
     {
       "country":"USA",
       "state":"CO",
       "city":"Denver",
       "name":"school 3"
     },
     {
        "country":"Canada",
       "state":"Ontario",
       "city":"Toronto",
       "name":"school 4"
     }
   ]
}

I need to group by on schools array on "country" then group by "state" then "city".

My typescript interface,

interface Person{
name:string;
age:number;
schools: School[];
}

interface School{
country:string;
states: State[];
}

interface State{
state:string;
pairs: Pair[];
}

interface Pair{
city:string;
name:string;
}

I need to write a service method to transform a json data to my model so that schools grouped by country and countries grouped by state and states grouped by city and name.

Is my model structure correct? If so, how can i do group by according to my need.

My service method should look like something like this,

getPerson():Observable<Person>
{
      return this.http.get(url to get json data).groupBy(XYZ..).....
}

Possible duplicate of How do I groupBy on a HTTP response?

mxr7350
– mxr7350

2017-09-06 14:54:13 +00:00
Commented Sep 6, 2017 at 14:54 — mxr7350
– mxr7350, Commented Sep 6, 2017 at 14:54

user4676340 · Accepted Answer · 2017-09-06 14:57:51Z

1

This isn't help, but a request ... Anyways here it is :

groupBy(array: any[], property: string) {
    return array.reduce((prev, next) => {
        // If the group doesn't exist, create it
        if(!prev[property]) { prev[property] = [next]; }
        // Else, we push it in
        else { prev[property].push(next); }
        // Mandatory return
        return prev;
    }, {});
}

Now you have a grouped object. You can either use it, or transform it into an array.

answered Sep 6, 2017 at 14:57

user4676340

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