Prevent duplicate entries in a JavaScript key-value data structure

Question

Prevent duplicate entries in a JavaScript key-value data structure

Seeking advice from a novice.

I am working on a project where I need to create a list with a Key/Value structure. I have assigned the Id as the Key and the rest of the information as the value, so as I add more records, they get appended to my list $scope.itemList[]

var data = [
              {
                id: 1,
                name : "Peter",
                lastname : "Smith",
                age : 36
              }, {
                id: 2,
                name : "Peter",
                lastname : "Smith",
                age : 36
              }
            ];

            $scope.itemList = [];
            angular.forEach(data, function(item){
                var obj = {};
                var valObj = {};

                valObj.name = item.name;
                valObj.lastname = item.lastname;
                valObj.age = item.age;

                obj[item.id] = valObj;
                $scope.itemList.push(obj);
            });

The challenge I am facing is handling duplicate records in the JSON file. The current code does not check for duplicate ids while pushing items to the list. I have tried various methods to compare the object with the item's id but none seem to be working.

I would greatly appreciate any assistance or guidance on how to address this issue.

javascript angularjs

Answer 1

Answer №1

To achieve the desired outcome, consider converting the itemList from a list to a dictionary. You can modify the structure like this:

var data = [
              {
                id: 1,
                name : "Peter",
                lastname : "Smith",
                age : 36
              }, {
                id: 2,
                name : "Peter",
                lastname : "Smith",
                age : 36
              }
            ];

            $scope.itemDictionary = {};
            angular.forEach(data, function(item){
                var obj = {};
                var valObj = {};

                valObj.name = item.name;
                valObj.lastname = item.lastname;
                valObj.age = item.age;

                obj[item.id] = valObj;
                if(!$scope.itemDictionary[item.id]){
                     $scope.itemDictionary[item.id] = obj;
                }
            });

Answer 2

To achieve the desired outcome, consider converting the itemList from a list to a dictionary. You can modify the structure like this:

var data = [
              {
                id: 1,
                name : "Peter",
                lastname : "Smith",
                age : 36
              }, {
                id: 2,
                name : "Peter",
                lastname : "Smith",
                age : 36
              }
            ];

            $scope.itemDictionary = {};
            angular.forEach(data, function(item){
                var obj = {};
                var valObj = {};

                valObj.name = item.name;
                valObj.lastname = item.lastname;
                valObj.age = item.age;

                obj[item.id] = valObj;
                if(!$scope.itemDictionary[item.id]){
                     $scope.itemDictionary[item.id] = obj;
                }
            });

Answer 3

Answer №2

Solution

var dataset = [
  {
    id: 1,
    name : "John1",
    lastname : "Doe",
    age : 30
  }, {
    id: 2,
    name : "John2",
    lastname : "Doe",
    age : 32
  }, {
    id: 3,
    name : "John3",
    lastname : "Doe",
    age : 35
  }
];

$scope.itemList = [];
angular.forEach(dataset, function(entry){
  var newObj = {};
  var valueObj = {};

  valueObj.name = entry.name;
  valueObj.lastname = entry.lastname;
  valueObj.age = entry.age;

  if ( !newObj[entry.id]) {
    newObj[entry.id] = valueObj;
    $scope.itemList.push(newObj);
  }

});

However, if there is no compelling reason for newObj[entry.id], you may consider using findIndex from lodash or a similar method.

I cannot see why you would need two separate objects in this case.

update

var dataset = [
  {
    id: 1,
    name : "John1",
    lastname : "Doe",
    age : 30
  }, {
    id: 2,
    name : "John2",
    lastname : "Doe",
    age : 32
  }, {
    id: 3,
    name : "John3",
    lastname : "Doe",
    age : 35
  }
];

$scope.itemsList = [];
angular.forEach(dataset, function(item){
  if(_.findIndex($scope.itemsList, function(listItem){ return item.id === listItem.id }) === -1){
    $scope.itemsList.push(item);
  }
});

Answer 4

Solution

var dataset = [
  {
    id: 1,
    name : "John1",
    lastname : "Doe",
    age : 30
  }, {
    id: 2,
    name : "John2",
    lastname : "Doe",
    age : 32
  }, {
    id: 3,
    name : "John3",
    lastname : "Doe",
    age : 35
  }
];

$scope.itemList = [];
angular.forEach(dataset, function(entry){
  var newObj = {};
  var valueObj = {};

  valueObj.name = entry.name;
  valueObj.lastname = entry.lastname;
  valueObj.age = entry.age;

  if ( !newObj[entry.id]) {
    newObj[entry.id] = valueObj;
    $scope.itemList.push(newObj);
  }

});

However, if there is no compelling reason for newObj[entry.id], you may consider using findIndex from lodash or a similar method.

I cannot see why you would need two separate objects in this case.

update

var dataset = [
  {
    id: 1,
    name : "John1",
    lastname : "Doe",
    age : 30
  }, {
    id: 2,
    name : "John2",
    lastname : "Doe",
    age : 32
  }, {
    id: 3,
    name : "John3",
    lastname : "Doe",
    age : 35
  }
];

$scope.itemsList = [];
angular.forEach(dataset, function(item){
  if(_.findIndex($scope.itemsList, function(listItem){ return item.id === listItem.id }) === -1){
    $scope.itemsList.push(item);
  }
});

Prevent duplicate entries in a JavaScript key-value data structure

Answer №1

Answer №2

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