使用node.js连接和聚合json对象数据

Question

I generate the following json in my Node application:

    [ { id: 1,
        name: 'user1',
        sport: 'athletics',
        medal_count: '1' 
      },
      { id: 1,
        name: 'user1',
        sport: 'tennis',
        medal_count: '2' 
      },
      { id: 2,
        name: 'user2',
        sport: ['football'],
        medal_count: '2' 
      }
    ]

I'd now like to concatenate users so that they appear as a single object with the sport listed in an array and the medal_count aggegrated for the user. The above json would look like this:

    [ { id: 1,
        name: 'user1',
        sport: [
          'athletics',
          'tennis'
        ],
        medal_count: '3' 
      },
      { id: 2,
        name: 'user2',
        sport: 'football',
        medal_count: '2' 
      }
    ]

How is this done? Am I correct in thinking this should be done with a map reduce function?

Answer 1

Edited

 let input = [{ id: 1, name: 'user1', sport: 'athletics', medal_count: '1' }, { id: 1, name: 'user1', sport: 'tennis', medal_count: '2' }, { id: 2, name: 'user2', sport: 'football', medal_count: '2' } ]; let grouped = {}; input.forEach(({id, name, sport, medal_count}) => { grouped[id] = grouped[id] || {id, name, sport: [], medal_count:0}; if (!grouped[id].sport.includes(sport)) grouped[id].sport.push(sport); grouped[id].medal_count = `${(+grouped[id].medal_count)+ (+medal_count)}`; }); grouped = Object.values(grouped); console.log(grouped); 

Answer 2

Yes, you are right:

 'use strict'; const data = [{ id: 1, name: 'user1', sport: 'athletics', medal_count: '1', }, { id: 1, name: 'user1', sport: 'tennis', medal_count: '2', }, { id: 2, name: 'user2', sport: 'football', medal_count: '2', }]; const out = data.reduce((accumulator, item) => { if (accumulator[item.id]) { const group = accumulator[item.id]; if (Array.isArray(group.sport)) { group.sport.push(item.sport); } else { group.sport = [group.sport, item.sport]; } group.medal_count = `${(+group.medal_count) + (+item.medal_count)}`; } else { accumulator[item.id] = item; } return accumulator; }, {}); console.log(JSON.stringify(out, null, 2)); 

Note that you are using numbers as strings for medal_count