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Kode
Kode

Reputation: 3225

AngularJS count number of items in JSON array where ID equals

I can get the overall count of a number of articles in a JSON array using the following:

Home.html

<div ng-controller="pfcArticleCountCtrl">Number of Articles {{articlecount.length}} items</div>

Controllers.js

// Count number of total articles
pfcControllers.controller('pfcArticleCountCtrl', ['$scope', 'pfcArticles', function ($scope, pfcArticles) {
$scope.articlecount = pfcArticles.query();

}]);

Services.js

// Articles by ID
pfcServices.factory('pfcArticles', ['$resource', function ($resource) {
    return $resource('https://myrestcall.net/tables/articles/:articleID', { articleID: '@id' },
    {
        'update': { method:'PATCH'}
    }
    );
}]);

But I would also like to display the number of articles by category. Here is an example JSON return:

[
{
"id": "66D5069C-DC67-46FC-8A51-1F15A94216D4",
"articletitle": "artilce1",
"articlecategoryid": 1,
"articlesummary": "article 1 summary. "
 },
{
"id": "66D5069C-DC67-46FC-8A51-1F15A94216D5",
"articletitle": "artilce2",
"articlecategoryid": 2,
"articlesummary": "article 2 summary. "
}, 
{
"id": "66D5069C-DC67-46FC-8A51-1F15A94216D6",
"articletitle": "artilce3",
"articlecategoryid": 3,
"articlesummary": "article 3 summary. "
},   
{
"id": "66D5069C-DC67-46FC-8A51-1F15A94216D7",
"articletitle": "artilce4",
"articlecategoryid": 1,
"articlesummary": "article 3 summary. "
}, 
]

In this instance the overall count is 4, but for Category 1, it should be 2. I want to display this on a page as follows:

Category 1 (2) Category 2 (1) Category 3 (1)

Total Articles (4)

How do I count the number of articles by category?

Upvotes: 0

Views: 2548

Answers (2)

Julien Roy
Julien Roy

Reputation: 309

You could use reduce to create an object with cat id as name and count as value : 

$scope.articleByCat = articles.reduce(function (prev, item) {

    if ( !! prev[item.articlecategoryid]) {
        //category already exist -> increment
        prev[item.articlecategoryid]++;
    } else {
        //category does not exist -> init
        prev[item.articlecategoryid] = 1;
    }
    return prev;
}, {});

You expose it by your scope and display it via ng-repat

<div ng-app='article' ng-controller='ArticleController'>
 <ul>
     <li ng-repeat='(key, value) in articleByCat'>Category {{key}} : {{value}}</li>
    </ul>
 </div>

A working jsfiddle

Upvotes: 2

vamsikrishnamannem
vamsikrishnamannem

Reputation: 4847

First sort the array var data = [ ];(your data)

data.sort(sort);

function sort(a,b) {
  if (a.articlecategoryid < b.articlecategoryid)
     return -1;
  if (a.articlecategoryid > b.articlecategoryid)
    return 1;
  return 0;
  }

Then count the duplicate values

var current = null;
    var cnt = 0;
    for (var i = 0; i < data.length; i++) {
        if (data[i].articlecategoryid != current) {
            if (cnt > 0) {
                document.write('Category'+current+'-->'+cnt+ ' times<br>');
            }
            current = data[i].articlecategoryid;
            cnt = 1;
        } else {
            cnt++;
        }
    }
    if (cnt > 0) {
        document.write('Category'+current+'-->'+cnt+ ' times');
    }

see the example in here

Upvotes: 0

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