javascript - Angular q 所有动态结果

Question

我需要等待两个 promise 在做某事之前解决。问题是有时我只能根据客户想要的发送一个 promise ，我需要指望来自这个 $q 的结果。全部。如何动态定义变量？

  var makePurchaseToResolve = [];

    if( CartService.items.draws.length ) {
      var drawOrder = {};
      drawOrder.price = $scope.getTotal();
      drawOrder.paymentMethodId = $scope.payment.paymetMethodId;
      drawOrder.orderItems = CartService.items.draws;
      drawOrder.payFromBalance = false;
      makePurchaseToResolve.push(DrawService.makePurchase(drawOrder));
    }

    if( CartService.items.hunters.length ) {
      var hunterOrder = {};
      hunterOrder.paymentMethodId = $scope.payment.paymetMethodId;
      hunterOrder.orderItems = CartService.items.hunters;
      makePurchaseToResolve.push(HunterService.makePurchase(hunterOrder));      
    }


$q.all(makePurchaseToResolve).then(function( res ) {
     $q.all([HunterService.getPurchase(res[0].data.data),DrawService.getPurchase(res.data.data)]).then(function() {

            //here is the problem, because i dont know if i have the two promises to resolve or only one

            $scope.hunters = res[0].data.data[0];
            $scope.drawOrder = res[1].data.data;          
          })
}

Answer 1

一个鲜为人知的事实是 $q.all 也可以接受一个对象而不是一个数组，这在这种情况下可以简化您的生活:

var purchases = {}; // an object rather than an array for named properties

if( CartService.items.draws.length ) {
  //...
  purchases.drawOrder = DrawService.makePurchase(drawOrder); // named assign
}

if( CartService.items.hunters.length ) {
  //...
  purchases.hunters = HunterService.makePurchase(hunterOrder);      
}

// any more additions to the objects here..

$q.all(purchases).then(function(resolved){
    // resolve anything further you need
    $scope.purchases = resolved; // Add $scope.purchases.hunters etc 
});

promises 在一个对象中解析，所以它们被命名，而不是有一个数组，你得到一个带有属性的解析对象，所以不要做 arr[0] ，这可能是乱序的，你会做 resolved.hunters 或resolved.drawOrder。该解决方案只是嵌套到 $scope 一级并自动执行。