我如何使用 nodejs/js 通过 id 找到一个 json 对象

Question

So I want to get the object by the id 1 in this object:

let users = {
  'users': {
    'user1': {
      'id': '1',
      'name': 'Brandon',
      'DOB': '05/04/2000'
    },
    'user2': {
      'id': '2',
      'name': 'Jefferson',
      'DOB': '05/19/2004'
    }
  }
}

and I want it to return the entire 'user1' array and log it, does anyone know how I could do this?

I looked all over stackoverflow, and docs, and couldn't find a way to do this. Could I get some help?

Answer 1

There are a few approaches, both of these should roughly achieve what you're looking for:

 let users = { 'users': { 'user1': { 'id': '1', 'name': 'Brandon', 'DOB': '05/04/2000' }, 'user2': { 'id': '2', 'name': 'Jefferson', 'DOB': '05/19/2004' } } } const findUserById = (id) => { const key = Object.keys(users.users).find(user => users.users[user].id === '1') return users.users[key] } console.log(findUserById('1'))

 let users = { 'users': { 'user1': { 'id': '1', 'name': 'Brandon', 'DOB': '05/04/2000' }, 'user2': { 'id': '2', 'name': 'Jefferson', 'DOB': '05/19/2004' } } } const findUserById = (id) => { const [key, user] = Object.entries(users.users).find(([key, user]) => user.id === '1'); return user; } console.log(findUserById('1'))

Answer 2

While the answer by skovy is right and this is what you should be doing in an actual production setting, I would advise against applying it immediately in your situation.

Why? Your question shows that you first need to learn some basic principles any JavaScript programmer should have, that is:

The simplest method used to iterate over an object's keys is the for .. in loop. When iterating over an object's keys using the for .. in loop, the code inside the curly brackets will be executed once for every key of the object we are iterating.

let users = {
   "user1": {
       "id": 1
   },
   "user2": {
       "id": 2
   }
}
for (let key in users) {
    console.log(key);
}

The above code will print:

user1
user2

Proceeding from that, it should be clear how to find the element we want:

let foundUser = null;
for (let key in users) {
    if (users[key].id === 1) {
        foundUser = users[key];
        break;
    }
}
// now found user is our user with id === 1 or null, if there was no such user

If you have a complex object which is a descendant of another object and don't want to iterate over inherited properties, you could instead get an array of current object's keys with Object.keys :

let users = {
   "user1": {
       "id": 1
   },
   "user2": {
       "id": 2
   }
}
const keys = Object.keys(users) // now this is an array containing just keys ['user1', 'user2'];
let foundUser = null;
// now you can iterate over the `keys` array using any method you like, e.g. normal for:
for (let i = 0; i < keys.length; i++) {
    if (users[keys[i]].id === 1) {
        foundUser = users[keys[i]];
        break;
    }
}
// or alternatively `for of`:
for (for key of keys) {
    if (users[key].id === 1) {
        foundUser = users[key];
        break;
    }
}

You could use Object.values to get an array containing all values of the object:

let users = {
   "user1": {
       "id": 1
   },
   "user2": {
       "id": 2
   }
}
const values = Object.values(users); // values: [{"id":1},{"id":2}]

You can now find the entry you want on your own:

let foundUser = null
for (let i = 0; i < values.length; i++) {
    if (values[i].id === 1) {
        foundUser = values[i];
        break;
    }
}

Or using the Array's find method :

let foundUser = values.find(user => user.id === 1);
// now foundUser contains the user with id === 1

Or, shorter and complete version:

let users = {
   "user1": {
       "id": 1
   },
   "user2": {
       "id": 2
   }
}
const foundUser = Object.values(users).find(user => user.id === 1);
// now foundUser is `{ id: 1 }`

Answer 3

A simple for loop would do it:

 let users = { 'users': { 'user1': { 'id': '1', 'name': 'Brandon', 'DOB': '05/04/2000' }, 'user2': { 'id': '2', 'name': 'Jefferson', 'DOB': '05/19/2004' } } } let desiredUser = {}; Object.keys(users.users).forEach((oneUser) => { if(users.users[oneUser].id === "1") desiredUser = users.users[oneUser]; }); console.log(desiredUser);

Answer 4

You can also use reduce for this... as well as if you wanted to return the "entire" object, you could do:

 let USER_LIST = { 'users': { 'user1': { 'id': '1', 'name': 'Brandon', 'DOB': '05/04/2000' }, 'user2': { 'id': '2', 'name': 'Jefferson', 'DOB': '05/19/2004' } } } function findUserById(id){ return Object.entries(USER_LIST.users).reduce((a, [user, userData]) => { userData.id == id ? a[user] = userData : ''; return a; }, {}); } console.log(findUserById(1));

Answer 5

I agree with the Answers. just a short and simple way is to use .find() method

 //--data returned-----//
 data = [{"Id":22,"Title":"Developer"},{"Id":45,"Title":"Admin"}]


      fs.readFile('db.json','utf8', function(err,data){
            var obj = JSON.parse(data);
            console.log(obj);
            var foundItem = obj.find(o=>o.Id==id);
            console.log(foundItem);
       });

Answer 6

Not a big fan of reinventing the wheel. We use object-scan for most of our data processing now. It's very handy when you can just use a tool for that kind of stuff. Just takes a moment to wrap your head around how to use it. Here is how it could answer your questions:

 // const objectScan = require('object-scan'); const find = (id, data) => objectScan(['**.id'], { abort: true, rtn: 'parent', filterFn: ({ value }) => value === id })(data); const users = { users: { user1: { id: '1', name: 'Brandon', DOB: '05/04/2000' }, user2: { id: '2', name: 'Jefferson', DOB: '05/19/2004' } } }; console.log(find('1', users)); // => { id: '1', name: 'Brandon', DOB: '05/04/2000' }

 .as-console-wrapper {max-height: 100% !important; top: 0}

 <script src="https://bundle.run/object-scan@13.8.0"></script>

Disclaimer : I'm the author of object-scan