使用Lodash将Javascript数组分组

Question

Transaction.ts

export class Transaction {
    id: string;
    category: Category = new Category();
    totalPrice: number;
}

Category .ts

export class Category {
    id: string;
    name: string;
}

I have an array of Transaction as shown below.

id:"1"
category: {id: "1", name: "Plumber"}
totalPrice: 500

id:"2"
category: {id: "1", name: "Plumber"}
totalPrice: 500

id:"3"
category: {id: "2", name: "Electrician"}
totalPrice: 1000

Now I need to group that data as shown below.

I have tried to group it using lodash . But unable to format the way which I need (as shown above). Can I have any support here?

This is what I tried. It just returned individual objects. After that?

let myArray = groupBy(this.data.transactions, (n) => {
      return n.category.name;
    });

Like this (data is different here.Just dummy data)

Update:

 let a = groupBy(this.data.transactions, (n) => {
      return n.category.name;
    }).map((objs, key) => ({
      'name': key,
      'totalPrice': sumBy(objs, 'totalPrice')
    })).value();

Above gives this error:

core.es5.js:1084 ERROR Error: Uncaught (in promise): TypeError: Object(...)(...).map is not a function TypeError: Object(...)(...).map is not a function

Update 2:

  const resultArray = [...reduce(this.data.transactions,(r, { totalPrice, category: { name } }) => {
      const item = r.get(name) || {
        name,
        totalPrice: 0
      };

      item.totalPrice += totalPrice;

      return r.set(name, item);
    }, new Map()).values()];

ERROR:

ERROR Error: Uncaught (in promise): TypeError: Object(...)(...).values(...).slice is not a function TypeError: Object(...)(...).values(...).slice is not a function

Answer 1

You need groupBy and sumBy ,

var grouped =  _(jsonarray)
    .groupBy('category.name')
    .map((objs, key) => ({
        'name': key,
        'totalPrice': _.sumBy(objs, 'totalPrice') }))
    .value();

DEMO

 var jsonarray = [{id:"1", category: {id: "1", name: "Plumber"}, totalPrice: 500 }, { id:"2", category: {id: "1", name: "Plumber"}, totalPrice: 500 }, { id:"3", category: {id: "2", name: "Electrician"}, totalPrice: 1000 }]; var grouped = _(jsonarray) .groupBy('category.name') .map((objs, key) => ({ 'name': key, 'totalPrice': _.sumBy(objs, 'totalPrice') })) .value(); console.log(grouped); 

 <script src='https://cdn.jsdelivr.net/lodash/4.17.2/lodash.min.js'></script>