JavaScript数组重组 [英] JavaScript array re structure

问题描述

我有一个包含学生和家长地址的数组.

I have an array with student and parent addresses.

例如，

  const users = [{
    id: 1,
    name: 'John',
    email: '[e-mail]',
    age: 25,
    parent_address: 'USA',
    relationship:'mother'
  },
  {
    id: 1,
    name: 'John',
    email: '[e-mail]',
    age: 25,
    parent_address: 'Spain',
    relationship:'father'
  },
  {
    id: 2,
    name: 'Mark',
    email: '[e-mail]',
    age: 28,
    parent_address: 'France',
    relationship:'father'
  }
];

我正在尝试将其重新格式化为以下结果.

I'm trying to reformat this to the following result.

const list = [
{
    id: 1,
    name: 'John',
    email: '[e-mail]',
    age: 25,
    parent: [
        {
            parent_address: 'USA',
            relationship:'mother'
        },{
            parent_address: 'Spain',
            relationship:'father'
        }
    ]
},
{
    id: 2,
    name: 'Mark',
    email: '[e-mail]',
    age: 28,
    parent:[
        {
            parent_address: 'France',
            relationship:'father'
        }
    ]
}
];

到目前为止，我尝试了以下方法.我不确定这是否正确.

So far I tried the following way. I'm not sure that is the right way or not.

const duplicateInfo = [];
for (var i = 0; i < user[0].length; i++) {
    var parent = [];
    if (duplicateInfo.indexOf(user[0][i].id) != -1) {
        // Do duplicate stuff
    } else {
        // Do other
    }
    duplicateInfo.push(user[0][i].id);
}

推荐答案

一种方法是使用

One approach would be to use .reduce() with an object as an accumulator. For each id, you can store an associated object with a parents array which you can append to in your .reduce() callback whenever you encounter a new object with the same id. Then to get an array of objects from your object, you can call Object.values() on it

请参见下面的示例:

const users = [{ id: 1, name: 'John', email: '[e-mail]', age: 25, parent_address: 'USA', relationship: 'mother' }, { id: 1, name: 'John', email: '[e-mail]', age: 25, parent_address: 'Spain', relationship: 'father' }, { id: 2, name: 'Mark', email: '[e-mail]', age: 28, parent_address: 'France', relationship: 'father' } ];
const res = Object.values(users.reduce((acc, {parent_address, relationship, ...r}) => { // use destructuring assignment to pull out necessary values
  acc[r.id] = acc[r.id] || {...r, parents: []}
  acc[r.id].parents.push({parent_address, relationship}); // short-hand property names allows us to use the variable names as keys
  return acc;
}, {}));

console.log(res);

由于您提到自己是JS的新手，所以以更强制的方式可能更易于理解(有关详细信息，请参见代码注释):

Since you mentioned you're new to JS, it may be easier to understand in a more imperative way (see code comments for details):

const users = [{ id: 1, name: 'John', email: '[e-mail]', age: 25, parent_address: 'USA', relationship: 'mother' }, { id: 1, name: 'John', email: '[e-mail]', age: 25, parent_address: 'Spain', relationship: 'father' }, { id: 2, name: 'Mark', email: '[e-mail]', age: 28, parent_address: 'France', relationship: 'father' } ];

const unique_map = {}; // create an object - store each id as a key, and an object with a parents array as its value
for(let i = 0; i < users.length; i++) { // loop your array object
  const user = users[i]; // get the current object
  const id = user.id; // get the current object/users's id
  
  if(!(id in unique_map)) // check if current user's id is in the the object
    unique_map[id] = { // add the id to the unique_map with an object as its associated value 
      id: id,
      name: user.name,
      email: user.email,
      age: user.age,
      parents: [] // add `parents` array to append to later
    }
    
  unique_map[id].parents.push({ // push the parent into the object's parents array
    parent_address: user.parent_address,
    relationship: user.relationship
  });
}

const result = Object.values(unique_map); // get all values in the unique_map
console.log(result);

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