javascript - 无法通过嵌套 promise 获得 $q.all - 等待所有

Question

我完全理解以前有人问过类似的问题，但我没有让它运行。我需要一个 promise 链，我需要等到所有 promise 都得到解决。

我的问题是我需要根据另一个 promise 的结果调用不同的 promise :-(

因此，根据 promise2 的结果，我的 promise4 是EITHER $translate.use OR 它是 $translate.refresh。

这是我目前所拥有的(已简化):

      
      var promise1 = someService.get({}).$promise.then(function (result) {
         // do stuff
      });

      var promise2 = anotherService.getPromise().then(function (result) {
        var properties = result[0];
        // do stuff
        return properties;
      });

      var promise3 = promise2.then(function(properties){

        // using $translate (angular-translate) here which is async as well

        var userLanguage = properties.language;
        if (userLanguage !== $translate.preferredLanguage()) {
          // either this is the 4th promise
          $translate.use(userLanguage).then(function (myVar) {
            // ...
          });
        } else {
          // or this is the 4th promise
          $translate.refresh().then(function (myVar) {
            // ...
          });
        }
      });

      var loadPromises = {
        promise1: promise1
        promise2: promise2
        promise3: promise3
        promise4: ???
      };

      $q.all(loadPromises).then(function (result) {
        // anything done
      });

Answer 1

你真的不需要监控promise3和promise4，你需要的只是promise1和promise2 . promise3 成为 promise2 的下一步。只需注意如何从 promise2 然后部分返回新的 promise (return $translate.use 或 return $translate.refresh):

var promise1 = someService.get({}).$promise.then(function(result) {
  // do stuff
});

var promise2 = anotherService.getPromise().then(function(result) {
  var properties = result[0];
  // do stuff
  return properties;
})
.then(function(properties) {

  // using $translate (angular-translate) here which is async as well

  var userLanguage = properties.language;
  if (userLanguage !== $translate.preferredLanguage()) {
    // either this is the 4th promise
    return $translate.use(userLanguage).then(function(myVar) {
      // ...
    });
  } else {
    // or this is the 4th promise
    return $translate.refresh().then(function(myVar) {
      // ...
    });
  }
});

var loadPromises = {
  promise1: promise1,
  promise2: promise2
};

$q.all(loadPromises).then(function(result) {
  // anything done
});