Mapping an array to another array using AngularJS

Question

Mapping an array to another array using AngularJS

I am working with two arrays - Users and Employments. Here is how they are structured:

Users       = [{id:1, name: "ryan"}, {id:2, name:"Julie"}]
Employments = [{user_id: 1, title: "manager"}, {user_id: 2, title: "Professor"}]

My goal is to display the Employments array using ng-repeat in the following way:

<li ng-repeat="employment in Employments">
  {{employment.user.name}}
</li>

Can someone help me understand how I can map the Users array to the Employments array?

javascript arrays angularjs

Answer 1

Answer №1

To display the employee name based on id, you can simply pass the id to a function and return the corresponding name. Here's how:

See Working Demo

html

<div ng-app='myApp' ng-controller="ArrayController">
    <li ng-repeat="employment in Employments">{{getEmployeeName(employment.user_id)}}
    </li>
</div>

script

var app = angular.module('myApp', []);
app.controller('ArrayController', function ($scope) {
    $scope.Users = [{
        id: 1,
        name: "ryan"
    }, {
        id: 2,
        name: "Julie"
    }];

    $scope.Employments = [{
        user_id: 1,
        title: "manager"
    }, {
        user_id: 2,
        title: "Professor"
    }];

    $scope.getEmployeeName = function (empId) {
        for (var i = 0; i < $scope.Users.length; i++) {
            if ($scope.Users[i].id === empId) {
                return $scope.Users[i].name;
            }
        };
    };
});

UPDATE 2

If you want to include User properties in the Employments array, follow this approach:

$scope.Users = [{id: 1, name: "ryan"}, {id: 2, name: "Julie"}];

$scope.Employments = [{user_id: 1, title: "manager"}, 
                      {user_id: 2, title: "Professor"}
                     ];

Code for combining User properties with Employments array

angular.forEach($scope.Users, function (user, userIndex) {
    angular.forEach($scope.Employments, function (employee, employeeIndex) {
        if (employee.user_id === user.id) {
            employee.name = user.name;
        }
    });
});

Output

$scope.Employments = [ { user_id: 1, title: "manager", name: "ryan" }, 
                       { user_id: 2, title: "Professor", name: "Julie" } 
                     ]

See Working Demo

UPDATE 3

Convert $scope.Users and $scope.Employments into a nested employee structure as shown below

$scope.employees = [];
angular.forEach($scope.Employments, function (employee, employeeIndex) {
    var employeeObject = {};
    employeeObject.title = employee.title;
    angular.forEach($scope.Users, function (user, userIndex) {
        if (employee.user_id === user.id) {
            employeeObject.user = user;
        }
    });
    $scope.employees.push(employeeObject);
});

Output

[ { title: "manager", user: { "id": 1, "name": "ryan" } }, 
  { title: "Professor", user: { "id": 2, "name": "Julie" } } 
]

See Working Demo

Answer 2

To display the employee name based on id, you can simply pass the id to a function and return the corresponding name. Here's how:

See Working Demo

html

<div ng-app='myApp' ng-controller="ArrayController">
    <li ng-repeat="employment in Employments">{{getEmployeeName(employment.user_id)}}
    </li>
</div>

script

var app = angular.module('myApp', []);
app.controller('ArrayController', function ($scope) {
    $scope.Users = [{
        id: 1,
        name: "ryan"
    }, {
        id: 2,
        name: "Julie"
    }];

    $scope.Employments = [{
        user_id: 1,
        title: "manager"
    }, {
        user_id: 2,
        title: "Professor"
    }];

    $scope.getEmployeeName = function (empId) {
        for (var i = 0; i < $scope.Users.length; i++) {
            if ($scope.Users[i].id === empId) {
                return $scope.Users[i].name;
            }
        };
    };
});

UPDATE 2

If you want to include User properties in the Employments array, follow this approach:

$scope.Users = [{id: 1, name: "ryan"}, {id: 2, name: "Julie"}];

$scope.Employments = [{user_id: 1, title: "manager"}, 
                      {user_id: 2, title: "Professor"}
                     ];

Code for combining User properties with Employments array

angular.forEach($scope.Users, function (user, userIndex) {
    angular.forEach($scope.Employments, function (employee, employeeIndex) {
        if (employee.user_id === user.id) {
            employee.name = user.name;
        }
    });
});

Output

$scope.Employments = [ { user_id: 1, title: "manager", name: "ryan" }, 
                       { user_id: 2, title: "Professor", name: "Julie" } 
                     ]

See Working Demo

UPDATE 3

Convert $scope.Users and $scope.Employments into a nested employee structure as shown below

$scope.employees = [];
angular.forEach($scope.Employments, function (employee, employeeIndex) {
    var employeeObject = {};
    employeeObject.title = employee.title;
    angular.forEach($scope.Users, function (user, userIndex) {
        if (employee.user_id === user.id) {
            employeeObject.user = user;
        }
    });
    $scope.employees.push(employeeObject);
});

Output

[ { title: "manager", user: { "id": 1, "name": "ryan" } }, 
  { title: "Professor", user: { "id": 2, "name": "Julie" } } 
]

See Working Demo

Answer 3

Answer №2

If you were looking to align the contents of two arrays using a template, you could utilize the following arrays

Users       = [{id:1, name: "ryan"}, {id:2, name:"Julie"}]
Employments = [{user_id: 1, title: "manager"}, {user_id: 2, title: "Professor"}]

Then implement a nested loop like this:

    <li ng-repeat="employment in Employments">
      <div ng-repeat="user in Users" ng-if="user.id === employment.user_id" >
        {{user.name}}:{{employment.title}}
      </div>
    </li>

Another helpful technique to prevent delays and unwanted symbols from displaying on your page is to use ng-bind and prefix attributes with data according to HTML specifications

        <li data-ng-repeat="employment in Employments">
          <div data-ng-repeat="user in Users" data-ng-if="user.id === employment.user_id" >
            <span data-ng-bind="user.name"></span>:<span data-ng-bind="employment.title"></span>
          </div>
        </li>

Even though you may only require the names, demonstrating how to incorporate the outer loop within the inner loop can still be beneficial. This concept also applies when using ng-init to reference the $index of the outer ng-repeat within the inner loop, but that may exceed the scope of what you're seeking.

Answer 4

If you were looking to align the contents of two arrays using a template, you could utilize the following arrays

Users       = [{id:1, name: "ryan"}, {id:2, name:"Julie"}]
Employments = [{user_id: 1, title: "manager"}, {user_id: 2, title: "Professor"}]

Then implement a nested loop like this:

    <li ng-repeat="employment in Employments">
      <div ng-repeat="user in Users" ng-if="user.id === employment.user_id" >
        {{user.name}}:{{employment.title}}
      </div>
    </li>

Another helpful technique to prevent delays and unwanted symbols from displaying on your page is to use ng-bind and prefix attributes with data according to HTML specifications

        <li data-ng-repeat="employment in Employments">
          <div data-ng-repeat="user in Users" data-ng-if="user.id === employment.user_id" >
            <span data-ng-bind="user.name"></span>:<span data-ng-bind="employment.title"></span>
          </div>
        </li>

Even though you may only require the names, demonstrating how to incorporate the outer loop within the inner loop can still be beneficial. This concept also applies when using ng-init to reference the $index of the outer ng-repeat within the inner loop, but that may exceed the scope of what you're seeking.

Answer 5

Answer №3

Plunker

This function organizes the names of users into the employments array:

var organizeUsers = function() {
  var index = 0;
  for (index; index < $scope.users.length; index++) {
    console.log($scope.users[index].id)
    for(var j = 0; j < $scope.employments.length; j++) {
      if($scope.employments[j].user_id === $scope.users[index].id) {
        $scope.employments[j].name = $scope.users[index].name;    
      }
    } 
  }
}

HTML:

<ul>
      <li ng-repeat="employment in employments">
  {{employment.name}}
      </li>
</ul>

Answer 6

Plunker

This function organizes the names of users into the employments array:

var organizeUsers = function() {
  var index = 0;
  for (index; index < $scope.users.length; index++) {
    console.log($scope.users[index].id)
    for(var j = 0; j < $scope.employments.length; j++) {
      if($scope.employments[j].user_id === $scope.users[index].id) {
        $scope.employments[j].name = $scope.users[index].name;    
      }
    } 
  }
}

HTML:

<ul>
      <li ng-repeat="employment in employments">
  {{employment.name}}
      </li>
</ul>

Answer 7

Answer №4

Yesterday, I encountered a similar issue. If you choose to utilize JavaScript, you will need to iterate through the loop twice. I suggest the most efficient approach would be to select all necessary data in a single query by joining tables if the data is coming from the same database.

You can retrieve User information with one query and Employment details with another query in the database. Then, iterate twice to organize them accordingly. Below is my proposed solution:

select users.*, employments.title from `users` inner join `employments` where users.id = employments.user_id;

I hope this solution proves to be useful.

Answer 8

Yesterday, I encountered a similar issue. If you choose to utilize JavaScript, you will need to iterate through the loop twice. I suggest the most efficient approach would be to select all necessary data in a single query by joining tables if the data is coming from the same database.

You can retrieve User information with one query and Employment details with another query in the database. Then, iterate twice to organize them accordingly. Below is my proposed solution:

select users.*, employments.title from `users` inner join `employments` where users.id = employments.user_id;

I hope this solution proves to be useful.

Mapping an array to another array using AngularJS

Answer №1

Answer №2

Answer №3

Answer №4

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