为什么我得到“没有将String隐式转换为整数（TypeError）”？

时间：2013-10-23 18:03:09

标签： ruby json

我有一些代码，我在非常相似的情况下运行。这是第一个情况，我有一部imdb_id部电影，我想要了解详情：

url = "http://mymovieapi.com/?id=#{self.imdb_id}&type=json&plot=none&episode=0&lang=en-US&aka=simple&release=simple&business=0&tech=0"
doc = Hpricot(open(url)).to_s
json = JSON.parse(doc)

puts json
puts json["imdb_id"]

这会得到以下结果：

{"rating_count"=>493949,
"genres"=>["Drama", "Romance"],
"rated"=>"PG-13",
"language"=>["English", "French", "German", "Swedish", "Italian", "Russian"],
"rating"=>7.6,
"country"=>["USA"],
"release_date"=>19980403,
"title"=>"Titanic",
"year"=>1997,
"filming_locations"=>"Santa Clarita, California, USA",
"imdb_id"=>"tt0120338",
"directors"=>["James Cameron"],
"writers"=>["James Cameron"],
"actors"=>["Leonardo DiCaprio", "Kate Winslet", "Billy Zane", "Kathy Bates", "Frances Fisher", "Gloria Stuart", "Bill Paxton", "Bernard Hill", "David Warner", "Victor Garber", "Jonathan Hyde", "Suzy Amis", "Lewis Abernathy", "Nicholas Cascone", "Anatoly M. Sagalevitch"],
"also_known_as"=>["Tai tan ni ke hao"],
"poster"=>{"imdb"=>"http://ia.media-imdb.com/images/M/MV5BMjExNzM0NDM0N15BMl5BanBnXkFtZTcwMzkxOTUwNw@@._V1_SY317_CR0,0,214,317_.jpg", "cover"=>"http://imdb-poster.b0.upaiyun.com/000/120/338.jpg!cover?_upt=66ac07591382594194"},
"runtime"=>["194 min"],
"type"=>"M",
"imdb_url"=>"http://www.imdb.com/title/tt0120338/"}

tt0120338

这是预期的。在第二种情况下，我有同一部电影的title和year：

url = "http://mymovieapi.com/?title=#{self.title}&type=json&plot=simple&episode=0&limit=1&year=#{self.year}&yg=1&mt=none&lang=en-US&offset=&aka=simple&release=simple&business=0&tech=0"
doc = Hpricot(open(url)).to_s
json = JSON.parse(doc)

puts json
puts json["imdb_id"]

从这里，我得到完全相同的JSON输出：

{"rating_count"=>493949,
"genres"=>["Drama", "Romance"],
"rated"=>"PG-13", "language"=>["English", "French", "German", "Swedish", "Italian", "Russian"],
"rating"=>7.6,
"country"=>["USA"],
"release_date"=>19980403,
"title"=>"Titanic",
"year"=>1997,
"filming_locations"=>"Santa Clarita, California, USA",
"imdb_id"=>"tt0120338",
"directors"=>["James Cameron"],
"writers"=>["James Cameron"],
"actors"=>["Leonardo DiCaprio", "Kate Winslet", "Billy Zane", "Kathy Bates", "Frances Fisher", "Gloria Stuart", "Bill Paxton", "Bernard Hill", "David Warner", "Victor Garber", "Jonathan Hyde", "Suzy Amis", "Lewis Abernathy", "Nicholas Cascone", "Anatoly M. Sagalevitch"],
"also_known_as"=>["Tai tan ni ke hao"],
"poster"=>{"imdb"=>"http://ia.media-imdb.com/images/M/MV5BMjExNzM0NDM0N15BMl5BanBnXkFtZTcwMzkxOTUwNw@@._V1_SY317_CR0,0,214,317_.jpg",
"cover"=>"http://imdb-poster.b0.upaiyun.com/000/120/338.jpg!cover?_upt=ec8bdec31382594417"},
"runtime"=>["194 min"],
"type"=>"M",
"imdb_url"=>"http://www.imdb.com/title/tt0120338/"}

但是当我尝试拨打puts json["imdb_id"]时，我收到此错误：

no implicit conversion of String into Integer (TypeError)

使用title和year获取时总会发生这种情况，但由于JSON输出完全相同，因此似乎无法解释。

3 个答案:

答案 0 :(得分：40)

从异常看，似乎第二个响应中的json是一个只有一个元素的数组，因此puts json的输出是相同的（括号不会输出{{1 }}}，但puts失败，因为json["string"]期望[]用作索引。

检查Integer或p json，如果确实是数组，请尝试使用json.is_a?(Array)。

答案 1 :(得分：3)

这是错误的以及如何解决它：

  • 您没有收回HTML，因此 NOT 需要解析HTML。请查看以下示例中doc的内容。请注意，没有HTML解析，也没有任何需要，因为您专门请求JSON响应：type=json。
  • 第一个请求会返回单个响应，因为您要求的是特定的imdb_id。你只能得到一个回复​​，所以你只得到一个对象/哈希。
  • 第二个请求会返回一组响应，因为可以是具有相同title和year的多个项目，但似乎不太可能。因此，您必须在解析JSON后从返回的数组中获取特定项。我使用first，但你的里程可能会有所不同，因为你可能会得到多个项目;如果你得到的不止一个，你必须弄清楚哪个是合适的。

以下是一些代码：

require 'json'
require 'open-uri'

imdb_id = 'tt0120338'
url = "http://mymovieapi.com/?id=#{ imdb_id }&type=json&plot=none&episode=0&lang=en-US&aka=simple&release=simple&business=0&tech=0"
doc = open(url).read
doc[0..5] # => "{\"rati"
json = JSON.parse(doc) # => {"rating_count"=>493949, "genres"=>["Drama", "Romance"], "rated"=>"PG-13", "language"=>["English", "French", "German", "Swedish", "Italian", "Russian"], "rating"=>7.6, "country"=>["USA"], "release_date"=>19980403, "title"=>"Titanic", "year"=>1997, "filming_locations"=>"Santa Clarita, California, USA", "imdb_id"=>"tt0120338", "directors"=>["James Cameron"], "writers"=>["James Cameron"], "actors"=>["Leonardo DiCaprio", "Kate Winslet", "Billy Zane", "Kathy Bates", "Frances Fisher", "Gloria Stuart", "Bill Paxton", "Bernard Hill", "David Warner", "Victor Garber", "Jonathan Hyde", "Suzy Amis", "Lewis Abernathy", "Nicholas Cascone", "Anatoly M. Sagalevitch"], "also_known_as"=>["Tai tan ni ke hao"], "poster"=>{"imdb"=>"http://ia.media-imdb.com/images/M/MV5BMjExNzM0NDM0N15BMl5BanBnXkFtZTcwMzkxOTUwNw@@._V1_SY317_CR0,0,214,317_.jpg", "cover"=>"http://imdb-poster.b0.upaiyun.com/000/120/338.jpg!cover?_upt=7dedce781382606097"}, "runtime"=>["194 min"], "type"=>"M", "imdb_url"=>"http://www.imdb.com/title/tt0120338/"}
json["imdb_id"] # => "tt0120338"

这会将单个项目作为JSON响应返回。您可以通过查看doc变量并查看它是JSON， NOT HTML来查看。使用JSON解析器解析它返回了一个哈希值。

url = "http://mymovieapi.com/?title=#{ json['title'] }&type=json&plot=simple&episode=0&limit=1&year=#{ json['year'] }&yg=1&mt=none&lang=en-US&offset=&aka=simple&release=simple&business=0&tech=0"
doc = open(url).read
doc[0..5] # => "[{\"rat"
json = JSON.parse(doc).first # => {"rating_count"=>493949, "genres"=>["Drama", "Romance"], "rated"=>"PG-13", "language"=>["English", "French", "German", "Swedish", "Italian", "Russian"], "rating"=>7.6, "country"=>["USA"], "release_date"=>19980403, "title"=>"Titanic", "year"=>1997, "filming_locations"=>"Santa Clarita, California, USA", "imdb_id"=>"tt0120338", "directors"=>["James Cameron"], "writers"=>["James Cameron"], "actors"=>["Leonardo DiCaprio", "Kate Winslet", "Billy Zane", "Kathy Bates", "Frances Fisher", "Gloria Stuart", "Bill Paxton", "Bernard Hill", "David Warner", "Victor Garber", "Jonathan Hyde", "Suzy Amis", "Lewis Abernathy", "Nicholas Cascone", "Anatoly M. Sagalevitch"], "plot_simple"=>"A seventeen-year-old aristocrat, expecting to be married to a rich claimant by her mother, falls in love with a kind but poor artist aboard the luxurious, ill-fated R.M.S. Titanic.", "poster"=>{"imdb"=>"http://ia.media-imdb.com/images/M/MV5BMjExNzM0NDM0N15BMl5BanBnXkFtZTcwMzkxOTUwNw@@._V1_SY317_CR0,0,214,317_.jpg", "cover"=>"http://imdb-poster.b0.upaiyun.com/000/120/338.jpg!cover?_upt=7dedce781382606097"}, "runtime"=>["194 min"], "type"=>"M", "imdb_url"=>"http://www.imdb.com/title/tt0120338/", "also_known_as"=>["Tai tan ni ke hao"]}
json["imdb_id"] # => "tt0120338"

此请求返回了一个哈希数组，这是合理的。 JSON字符串是一个数组，在doc变量中可见。解析它，然后只抓取第一个元素，就可以读取imdb_id的值。

再次注意，没有涉及HTML解析器，也不需要。你必须查看你要回来的数据，不要只是假设。

答案 2 :(得分：0)

错误必须在我的代码中的其他地方。

我将你给出的JSON设置为IRB中的变量a :(第二个例子中的JSON）

1.9.3p194 :043 > a
 => {"rating_count"=>493949, "genres"=>["Drama", "Romance"], "rated"=>"PG-13", "language"=>["English", "French", "German", "Swedish", "Italian", "Russian"], "rating"=>7.6, "country"=>["USA"], "release_date"=>19980403, "title"=>"Titanic", "year"=>1997, "filming_locations"=>"Santa Clarita, California, USA", "imdb_id"=>"tt0120338", "directors"=>["James Cameron"], "writers"=>["James Cameron"], "actors"=>["Leonardo DiCaprio", "Kate Winslet", "Billy Zane", "Kathy Bates", "Frances Fisher", "Gloria Stuart", "Bill Paxton", "Bernard Hill", "David Warner", "Victor Garber", "Jonathan Hyde", "Suzy Amis", "Lewis Abernathy", "Nicholas Cascone", "Anatoly M. Sagalevitch"], "also_known_as"=>["Tai tan ni ke hao"], "poster"=>{"imdb"=>"http://ia.media-imdb.com/images/M/MV5BMjExNzM0NDM0N15BMl5BanBnXkFtZTcwMzkxOTUwNw@@._V1_SY317_CR0,0,214,317_.jpg", "cover"=>"http://imdb-poster.b0.upaiyun.com/000/120/338.jpg!cover?_upt=ec8bdec31382594417"}, "runtime"=>["194 min"], "type"=>"M", "imdb_url"=>"http://www.imdb.com/title/tt0120338/"}

然后我打电话给：

1.9.3p194 :046 > puts a["imdb_id"]
tt0120338
 => nil

这给了我正确的输出。

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