Question

我正在构建一个包含四个函数的promise链。承诺的目的是进行一些API调用。每个API调用都会影响下一个，有些需要多个参数。

以下代码的基本流程如下：

geocodeLocation是第一个函数，它将$scope.location输入进行地理编码，该对象包含result，lat和{{1}的lng对象}}
formattedAddress是第二个需要前一个函数getSearchCount的函数。此函数使用Restangular查询API并返回result对象。
plucked_result函数需要saveLocation和result创建新位置，具体取决于plucked_result是否小于plucked_result.search_count。此函数返回1变量。
search_count需要getPhotos和result个参数。使用它们构建一个被激活的API请求URL。当响应返回时，search_count将保存到数据库。

错误发生在photos函数中。返回的错误是：

saveLocation

这是代码（对正在发生的事情做了一些评论）：

TypeError: Cannot read property 'search_count' of undefined

这里的问题是：如何在所有函数之间传递var geocodeLocation, getPhotos, getSearchCount, saveLocation; // geocode the $scope.location into a formatted address with latitude and longitude geocodeLocation = function(location) { return Geocoder.geocodeAddress(location).then(function(result) { $scope.geocodingResult = "(lat, lng) " + result.lat + ", " + result.lng + " (address: '" + result.formattedAddress + "')"; console.log(result); // pass the result object from the previous function into the next function return result; }); }; getSearchCount = function(result) { // fetch the locations from the API (using Restangular) return Global.locationsRoute().getList().then(function(data) { var plucked_result; // use underscore's _findWhere to pluck out the location we're looking for, and extract it's search_count plucked_result = _.findWhere(data, { name: result.formattedAddress }); // this is logging correctly console.log(plucked_result); return plucked_result; }); }; saveLocation = function(plucked_result, result) { var newLocation, search_count; // this is logging incorrectly, and is where the error occurs search_count = plucked_result.search_count; console.log(search_count); // if the search_count is more than 1, increment and update the search_count if (!(search_count < 1)) { plucked_result.search_count = search_count + 1; } else { // if the search_count is less than 1, create a new location newLocation = { name: result.formattedAddress, lat: result.lat, lng: result.lng, search_count: 1 }; Global.locationsRoute().post(newLocation); } return search_count; }; // this function requires both the result and search count to build the 500px API request string getPhotos = function(result, search_count) { var newUrl, url; url = Global.externalAPI() + "search?geo=" + result.lat + "," + result.lng + ",25km&rpp=5&image_size=4&tags=true&sort=votes_count&only=[Landscapes][City+%26+Architecture][Nature][Urban+Exploration][Underwater][Travel][Journalism][Black+and+White]&page=" + search_count + "&consumer_key=" + Global.consumerKey(); newUrl = Restangular.oneUrl('500px', url).get(); return newUrl.then(function(data) { var newPhoto, photo, _i, _len, _ref, _results; $scope.photos = data; _ref = data.photos; _results = []; for (_i = 0, _len = _ref.length; _i < _len; _i++) { photo = _ref[_i]; newPhoto = { name: photo.name, description: photo.description, image_url: photo.image_url, search_term: result.formattedAddress }; _results.push(Global.photosRoute().post(newPhoto)); } return _results; }); }; $scope.geocode = function() { var location; if ($scope.location) { location = $scope.location; return geocodeLocation(location).then(getSearchCount).then(saveLocation).then(getPhotos); } };，result和plucked_result变量？

Answer 1

解决。 Promise不能在它们之间传递多个参数，因此您需要将所有对象和变量捆绑到一个数组中，并在函数之间传递该数组。例如：

var getSearchCount, saveLocation;

getSearchCount = function(result) {
  return Global.locationsRoute().getList().then(function(data) {
    var passed_data, plucked_result;
    plucked_result = _.findWhere(data, {
      name: result.formattedAddress
    });
    passed_data = [result, plucked_result];
    return passed_data;
  });
};

saveLocation = function(passed_data) {
  var newLocation, plucked_result, result, search_count;
  result = passed_data[0];
  plucked_result = passed_data[1];
  search_count = plucked_result.search_count;
  if (!(search_count < 1)) {
    plucked_result.search_count = search_count + 1;
    plucked_result.put();
  } else {
    newLocation = {
      name: result.formattedAddress,
      lat: result.lat,
      lng: result.lng,
      search_count: 1
    };
    Global.locationsRoute().post(newLocation);
  }
  passed_data = [result, search_count];
  return passed_data;
};

其中passed_data是包含对象和变量的数组。

在AngularJS中的promises之间传递参数时出错

1 个答案: