CODEWITHSUNDEEP
javascriptnode.jsjson
n212
n212

Reputation: 607

How to remove an object from a json file

I need to be able to remove a specific object from my json file so I can renew the time.

At the moment I've tried to use a for loop to find the right one but this doesn't work and it just adds a new object without removing the old one.

How would you be able to remove the old object from the json file?

nodejs

function updateTime(id,name) {

  var newServer = {
    "id": id,
    "name": name,
    "time": new Date()
  }

  var id = id;

  fs.readFile('servers.json', function (err, data) {
    var json = JSON.parse(data);
    json.push(newServer);


      // for loop to check if the server has already been added in the json file.
      for(var i = 0; i < json.length; i++) {
        var id = json[i].id;
          delete json[i][id];
          console.log("removed " + json[i][id]);
          // return;
      }



    fs.writeFile("servers.json", JSON.stringify(json, null, 4), function (err) {
        if (err) throw err;
        console.log('Saved new server!');
      });
   });
}

json file

[
    {
        "id": "728374892403228752",
        "name": "test2",
        "time": "2020-07-02T23:06:59.889Z"
    },
    {
        "id": "725475771321155605",
        "name": "test server",
        "time": "2020-07-02T23:06:59.889Z"
    }
]

Upvotes: 0

Views: 2724

Answers (3)

javascwipt
javascwipt

Reputation: 1178

You are overwriting the id in the global scope, so you want to make sure they the array of objects has all unique ids

function updateTime(id,name) {

  var newServer = {
    "id": id,
    "name": name,
    "time": new Date()
  }

  fs.readFile('servers.json', function (err, data) {
    var json = JSON.parse(data);
    json.push(newServer);


      // for loop to check if the server has already been added in the json file.
      var duplicates = 0
      var newJson = []
       // count the duplicates to make sure there is only one of that object with the id
      for(var i = 0; i < json.length; i++) {
         if(json[i].id === id) {
           duplicates++
         }
          if(duplicates <=1) {
            newJson.push(json[i])
          }
      }



    fs.writeFile("servers.json", JSON.stringify(newJson, null, 4), function (err) {
        if (err) throw err;
        console.log('Saved new server!');
      });
   });
}

Upvotes: 0

Marlo D
Marlo D

Reputation: 56

Appears that the for-loop would remove the id property from each object.

If you'd like to remove the object containing a specific id, you could use the filter method on Array.

json.filter(entry => entry.id !== specificId);

Upvotes: 1

halilcakar
halilcakar

Reputation: 1648

If you need to remove spesific objects in an array you can filter them out. Consider following.

fs.readFile('servers.json', function (err, data) {
    var json = JSON.parse(data);
    json.push(newServer);
    // So you need to have an id of an object to remove
    // so lets say that it's 728374892403228752 this number.
    var idToRemove = 728374892403228752;
    // So this will filter out that object with an id of `idToRemove`
    json = json.filter(child => parseInt(child.id) !== idToRemove);
    // after this you can do your fileWrite again :)
    //...
}

Upvotes: 1

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