When should ng-repeat be utilized: only when the object type is an array?

Question

When should ng-repeat be utilized: only when the object type is an array?

I have a detailed object structure below:

$scope.document = 
 {
  "GENERAL_FIELDS": {
    "Source_Type": "custom",
    "Annotations": [
      "216/content/Factiva_CM_001/Proteins",
      "216/content/Factiva_CM_001/Fact"
    ],
    "Content": [
      "   Baculovirus; Budded virus; Ultrastructure; Cryo-EM;"
    ],
    "Title": [
      "Budded baculovirus particle structure revisited"
    ]
  },
  "stn": {
    "Document_Type": [
      "Journal",
      "Article"
    ]
  }
}

My goal is to display all the fields within "GENERAL_FIELDS" and "stn". The values of these fields can be either strings or arrays of strings. If it's an array, I want to iterate over each item and show the content. Below is my HTML markup:

<div id="titsec" class="comdocdet"  ng-repeat="(category, group) in document">
   <div ng-repeat="(key, value) in group">
      <div class="pTitle">
         {{key}}
      </div>
      <div class="contdesc">
         <div ng-if="Array.isArray(value)">
            <div ng-repeat="v in value">
               {{v}}
            </div>
         </div>
         <div ng-if="!Array.isArray(value)">
            {{value}}
         </div>
      </div>
   </div>
</div>

However, the ng-if="Array.isArray(value)" statement never evaluates to true and the array fields are shown as objects like: ["Journal","Article"]. What am I overlooking?

javascript angularjs arrays

Answer 1

Answer №1

To implement this functionality in your controller, simply add the following code:

 $scope.isArray = angular.isArray;

Then, update your HTML like so:

<div ng-if="isArray(value)">
  <div ng-repeat="v in value">
    {{v}}
  </div>
</div>
<div ng-if="!isArray(value)">
            {{value}}
</div>

Answer 2

To implement this functionality in your controller, simply add the following code:

 $scope.isArray = angular.isArray;

Then, update your HTML like so:

<div ng-if="isArray(value)">
  <div ng-repeat="v in value">
    {{v}}
  </div>
</div>
<div ng-if="!isArray(value)">
            {{value}}
</div>

Answer 3

Answer №2

It is recommended to refrain from directly accessing a method on the Array object within the template. Instead, it is suggested to handle this in the controller. For instance:

<div ng-if="vm.isValueAnArray(value)">
  // Some html
</div>

Your controller can contain the following logic:

function isValueAnArray(val) {
  return Array.isArray(val);
}

While untested, the best practice is to keep the logic in the controller rather than the template.

Answer 4

It is recommended to refrain from directly accessing a method on the Array object within the template. Instead, it is suggested to handle this in the controller. For instance:

<div ng-if="vm.isValueAnArray(value)">
  // Some html
</div>

Your controller can contain the following logic:

function isValueAnArray(val) {
  return Array.isArray(val);
}

While untested, the best practice is to keep the logic in the controller rather than the template.

Answer 5

Answer №3

Dealing with Scoping in Templates

When it comes to scoping, the template's scope is relative to the controller's scope. This means that references to variables like $scope.Array will look for them within the controller's scope.

To address this issue, one approach is to utilize

ng-if="window.Array.isArray(value)"

. For a practical demonstration, refer to the example provided below.

Alternatively, you could set $scope.Array = Array.prototype in the controller. By doing so, you eliminate the need to explicitly reference window before calling functions like Array.isArray().

A different strategy involves creating an alias for Array.isArray() within the controller's scope:

$scope.isValueAnArray = Array.isArray;

This way, you can simply invoke the function to determine whether a given value is an array or not.

angular.module('ang', [])
  .controller('cont', function($scope) {
    //use this to avoid referencing window in the template
    //$scope.Array = Array.prototype;
    $scope.document = {
      "GENERAL_FIELDS": {
        "Source_Type": "custom",
        "Annotations": [
          "216/content/Factiva_CM_001/Proteins",
          "216/content/Factiva_CM_001/Fact"
        ],
        "Content": [
          "   Baculovirus; Budded virus; Ultrastructure; Cryo-EM;"
        ],
        "Title": [
          "Budded baculovirus particle structure revisited"
        ]
      },
      "stn": {
        "Document_Type": [
          "Journal",
          "Article"
        ]
      }
    }
  });

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app="ang" ng-controller="cont">
  <div id="titsec" class="comdocdet" ng-repeat="(category, group) in document">
    <div ng-repeat="(key, value) in group">
      <div class="pTitle">
        {{key}}
      </div>
      <div class="contdesc">
        <div ng-if="window.Array.isArray(value)">
          <div ng-repeat="v in value">
            {{v}}
          </div>
        </div>
        <div ng-if="!window.Array.isArray(value)">
          {{value}}
        </div>
      </div>
    </div>
  </div>
</div>

Answer 6

Dealing with Scoping in Templates

When it comes to scoping, the template's scope is relative to the controller's scope. This means that references to variables like $scope.Array will look for them within the controller's scope.

To address this issue, one approach is to utilize

ng-if="window.Array.isArray(value)"

. For a practical demonstration, refer to the example provided below.

Alternatively, you could set $scope.Array = Array.prototype in the controller. By doing so, you eliminate the need to explicitly reference window before calling functions like Array.isArray().

A different strategy involves creating an alias for Array.isArray() within the controller's scope:

$scope.isValueAnArray = Array.isArray;

This way, you can simply invoke the function to determine whether a given value is an array or not.

angular.module('ang', [])
  .controller('cont', function($scope) {
    //use this to avoid referencing window in the template
    //$scope.Array = Array.prototype;
    $scope.document = {
      "GENERAL_FIELDS": {
        "Source_Type": "custom",
        "Annotations": [
          "216/content/Factiva_CM_001/Proteins",
          "216/content/Factiva_CM_001/Fact"
        ],
        "Content": [
          "   Baculovirus; Budded virus; Ultrastructure; Cryo-EM;"
        ],
        "Title": [
          "Budded baculovirus particle structure revisited"
        ]
      },
      "stn": {
        "Document_Type": [
          "Journal",
          "Article"
        ]
      }
    }
  });

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app="ang" ng-controller="cont">
  <div id="titsec" class="comdocdet" ng-repeat="(category, group) in document">
    <div ng-repeat="(key, value) in group">
      <div class="pTitle">
        {{key}}
      </div>
      <div class="contdesc">
        <div ng-if="window.Array.isArray(value)">
          <div ng-repeat="v in value">
            {{v}}
          </div>
        </div>
        <div ng-if="!window.Array.isArray(value)">
          {{value}}
        </div>
      </div>
    </div>
  </div>
</div>

When should ng-repeat be utilized: only when the object type is an array?

Answer №1

Answer №2

Answer №3

Dealing with Scoping in Templates

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