javascript - AngularJS 计算 JSON 数组中 ID 等于的项目数

Question

我可以使用以下命令获取 JSON 数组中文章的总数:

首页.html

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

Controller .js

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

}]);

服务.js

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

但我还想按类别显示文章数量。下面是一个 JSON 返回示例:

[
{
"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. "
}, 
]

在本例中，总计数为 4，但对于类别 1，它应该为 2。我想在页面上显示它，如下所示:

类别 1 (2) 类别 2 (1) 类别 3 (1)

文章总数(4)

如何按类别统计文章数量？

Answer 1

您可以使用reduce创建一个以cat id为名称并以count为值的对象:

$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;
}, {});

您通过范围公开它并通过 ng-repat 显示它

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

工作中jsfiddle