Question

我试图从我的JSON请求中显示哈希的内部级别。

这是JSON请求的返回：

{
    "results": [
    {
    "utc_offset": -25200000,
    "venue": {
      "zip": "94305",
      "country": "us",
      "localized_country_name": "USA",
      "city": "Stanford",
      "address_1": "750 Escondido Road",
      "name": "Ray's - Graduate Community Center",
      "lon": -122.158386,
      "id": 5612552,
      "state": "CA",
      "lat": 37.423393,
      "repinned": false
    },
    "status": "upcoming"
    },
    {
    "utc_offset": -25200000,
    "venue": {
      "zip": "94306",
      "country": "us",
      "localized_country_name": "USA",
      "city": "Palo Alto",
      "address_1": "25 Churchill Ave",
      "name": "Palo Alto High School",
      "lon": -122.154121,
      "id": 1566333,
      "state": "CA",
      "lat": 37.433186,
      "repinned": false
    },
    "status": "upcoming"
    },
    {
    "utc_offset": -25200000,
    "venue": {
      "zip": "94306",
      "country": "us",
      "localized_country_name": "USA",
      "city": "Palo Alto",
      "address_1": "25 Churchill Ave",
      "name": "Palo Alto High School",
      "lon": -122.154121,
      "id": 1566333,
      "state": "CA",
      "lat": 37.433186,
      "repinned": false
    },
    "status": "upcoming"
    }
    ]
    }
}

我已提及：How to use JSON data returned by API call in Rails 4，How to get a second level field from json file using ruby，Why do I get "no implicit conversion of String into Integer (TypeError)"?，How to access JSON in Rails?

这帮助我达到了这一点，如果我使用返回@result = @api_response["results"][0]["venue"]["name"]的{{1}}指定数组索引，我可以显示哈希的内部级别。这就是我想要显示的内容，但我想显示列表中所有场所的名称，而不仅仅是索引[0]上的名称。但我不确定如何遍历索引。

我还可以使用"Ray's - Graduate Community Center"显示散列结果，并使用：

进行迭代

@result = @api_response["results"]

返回：

<% @result.each do |i| %>
  <%= i["venue"] %>
<% end %>

但是当我尝试使用它时：

{"zip"=>"94305", "country"=>"us", "localized_country_name"=>"USA", "city"=>"Stanford", "address_1"=>"750 Escondido Road", "name"=>"Ray's - Graduate Community Center", "lon"=>-122.158386, "id"=>5612552, "state"=>"CA", "lat"=>37.423393, "repinned"=>false} 
{"zip"=>"94305", "country"=>"us", "localized_country_name"=>"USA", "city"=>"Stanford", "address_1"=>"750 Escondido Road", "name"=>"Ray's - Graduate Community Center", "lon"=>-122.158386, "id"=>5612552, "state"=>"CA", "lat"=>37.423393, "repinned"=>false} 
{"zip"=>"94306", "country"=>"us", "localized_country_name"=>"USA", "city"=>"Palo Alto", "address_1"=>"25 Churchill Ave", "name"=>"Palo Alto High School", "lon"=>-122.154121, "id"=>1566333, "state"=>"CA", "lat"=>37.433186, "repinned"=>false} 
{"zip"=>"94306", "country"=>"us", "localized_country_name"=>"USA", "city"=>"Palo Alto", "address_1"=>"25 Churchill Ave", "name"=>"Palo Alto High School", "lon"=>-122.154121, "id"=>1566333, "state"=>"CA", "lat"=>37.433186, "repinned"=>false} 

{"zip"=>"94306", "country"=>"us", "localized_country_name"=>"USA", "city"=>"Palo Alto", "address_1"=>"25 Churchill Ave", "name"=>"Palo Alto High School", "lon"=>-122.154121, "id"=>1566333, "state"=>"CA", "lat"=>37.433186, "repinned"=>false} 
{"zip"=>"94306", "country"=>"us", "localized_country_name"=>"USA", "city"=>"Palo Alto", "address_1"=>"25 Churchill Ave", "name"=>"Palo Alto High School", "lon"=>-122.154121, "id"=>1566333, "state"=>"CA", "lat"=>37.433186, "repinned"=>false}

我得到<% @result.each do |i| %> <%= i["venue"]["name"] %> <br /> <% end %> []＆＃39;对于nil：NilClass`错误，它不允许我访问＆＃34; name＆＃34;在＆＃34;场地内＃34;这是我想要展示的。

我是否在正确的轨道上？有没有更好的方法来显示哈希的内部级别？任何反馈都会有帮助。谢谢！

Answer 1

您确定results数组中的每个对象都有一个venue字段吗？

在尝试访问venue字段之前，请确保查看对象是否确实存在。在您的控制器中，添加此

@result = @api_response["results"].reject {|obj| obj.nil?}

这将删除数组中nil的所有对象。

如果对象存在但字段venue没有？

，该怎么办？

<% @result.each do |i| %>
  <%= i.has_key? "venue" ? i["venue"]["name"] : 'Location unspecified' %> <br />
<% end %>

如果这看起来很乱，你也可以将它移到辅助方法，如

def venue_name(obj)
  obj.has_key? "venue" ? obj["venue"]["name"] : 'Location unspecified'
end

然后在视图中使用它。

 <% @result.each do |i| %>
  <%= venue_name(i) %> <br/>
 <% end %>

Answer 2

看起来你走在正确的轨道上;只是因为那里的结果是零或者没有其中的场所。

您如何处理问题取决于您希望如何处理这些情况。

您可以过滤结果，以排除没有场地的结果。在查询中执行此操作会更有效，但您可以这样做：

@result.select { |r| r.present? && r.has_key?('venue') }.each do |i|

或者你可以输出＆＃34;没有场地＆＃34;或者如果场地不见了。我倾向于在这种情况下使用fetch。您可以尝试从散列中获取值，但如果散列中的键不是，则返回默认值。所以，在你的情况下，你可以这样做：

<%= i.fetch('venue', {}).fetch('name', 'No venue') %>

这会在结果中查找场地哈希，但如果不在那里则返回空哈希。第二个fetch然后尝试从该哈希中检索名称，如果找不到，则再次返回'No venue'。

Rails如何从JSON请求显示哈希

2 个答案: