递归$ http.get for循环

问题描述

我使用Angular 1.5。我有一个查询类别的功能，然后对每个类别，它查询产品。我想在所有产品被检索后显示一条消息，检索了多少条。它输出0.什么是解决方案？

  function getProducts（）{
 vm.categories = []; 
 var prodcount = 0; 
 $ b $ http.get（localhost / menu / 1 / categories）
 .then（function（response）{
 var categories = response.data; 
 angular.forEach（类别，功能（猫）{
 $ http.get（localhost / category /+ cat.id +/ products）
 .then（function（response）{
 cat.products = response.data; 
 vm.categories.push（cat）; 
 prodcount + = cat.products.length; 
}）; 
}）; 
 $ mdToast.show（$ mdToast.simple（）。textContent（retrieve+ vm.categories.length +categories and，+ prodcount +products !.））; 
}） ; 
 
  

解决方案

异步请求和承诺如何工作。
为了让你的代码运行，你可以这样做：
var promises = []; //创建一个数组来存储承诺

  angular.forEach（categories，function（cat）{
 
 //捕获承诺
 var requestPromise = $ http.get（...）
 .then（function（response）{
 ... 
}）; 
 Promises.push（requestPromise）; //将它添加到数组
}）; 
 
 //当数组中的所有承诺都被解决的时候，这个承诺将被解决。 
 $ q.all（promises）.then（function（）{
 $ mdToast.show（...）; 
}）
 
}）; 
  

但这种做法不太好。你应该尽量减少请求的数量，最好只做一个。

I use Angular 1.5. I have a function that queries Categories, then for each category, it queries Products. I want to show a message after all the products are retrieved, how many were retrieved. It outputs 0. What is the solution?

function getProducts() {
  vm.categories = [];
  var prodcount = 0;

  $http.get("localhost/menu/1/categories")
    .then(function(response) {
      var categories = response.data;
      angular.forEach(categories, function(cat) {
        $http.get("localhost/category/" + cat.id + "/products")
          .then(function(response) {
            cat.products = response.data;
            vm.categories.push(cat);
            prodcount += cat.products.length;
          });
      });
      $mdToast.show($mdToast.simple().textContent("retrieved " + vm.categories.length + " categories and, " + prodcount + " products!."));
    });
}

解决方案

You should take a look at how asynchronous requests and promises works.To make your code run you could do this: var promises = []; // Creates an array to store the promises

angular.forEach(categories, function(cat) {

    // Capture the promise
    var requestPromise = $http.get(...)
    .then(function(response) {
        ...
    });
    promises.push(requestPromise);  // Add it to the array
  });

  // This promise will be resolved when all promises in the array have been resolved as well.
  $q.all(promises).then(function(){
     $mdToast.show(...);
  })

});

But this approach is not quite good. You should try to minimize the amount of requests, doing only one preferably.

http://www.martin-brennan.com/using-q-all-to-resolve-multiple-promises/http://andyshora.com/promises-angularjs-explained-as-cartoon.html

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