在AngularJS中的承诺之间传递论据时出错

Question

我正在构建一个包含四个功能的承诺链。 许诺的目的是进行一些API调用。 每个API调用都会影响以下调用，某些调用需要多个参数。

下面的代码的基本流程是这样的：

1. geocodeLocation是第一个函数，并接受$scope.location输入，该输入将被地理编码到包含lat ， lng和formattedAddress的result对象中
2. getSearchCount是第二个函数，需要上一个函数的result 。 该函数使用Restangular查询API，并返回一个plucked_result对象。
3. saveLocation函数根据plucked_result.search_count是否小于1 ，需要result和plucked_result来创建一个新位置。 此函数返回search_count变量。
4. getPhotos需要使用result和search_count参数。 使用这些工具，可以构建一个可以触发的API请求URL。 当响应返回时， photos将保存到数据库。

该错误发生在saveLocation函数中。 返回的错误是：

TypeError: Cannot read property 'search_count' of undefined

这是代码（对正在发生的事情有一些评论）：

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);
  }
};

这里的问题是：如何在所有函数之间传递result ， plucked_result和search_count变量？

Answer 1

解决了。 承诺之间不能传递多个参数，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。