如何循环OpenStruct键/值对

Question

我有以下OpenStruct数据结构，我正在尝试获取键/值对

> #<OpenStruct conditions=[#<OpenStruct field="Out_of_country", operator="us", values=["true"]>, #<OpenStruct field="Status__c",
> operator="jp", values=["'Approved'"]>, #<OpenStruct field="Status__c",
> operator="gb", values=["'Rejected'"]>], conjunction="and">

Ruby代码：

dataResult = nil
dataResult = data['condition'].include?('out_of_country']

这就是从OpenStruct中提取键/值对的方式吗？

更新：

您说得对，我使用的是to_s，我删除了它，下面是我试图访问的键/值

myresult = data['mainCondtion']
p myresult --> I got this result:

  > #<OpenStruct conditions=[#<OpenStruct field="Out_of_country", operator="us", values=["true"]>, #<OpenStruct field="Status__c",
    > operator="jp", values=["'Approved'"]>, #<OpenStruct field="Status__c",
    > operator="gb", values=["'Rejected'"]>], conjunction="and">

然后我尝试访问field和values

myresult.each_pair{ |key, value| puts "#{key}: #{value}" }

我得到了这个错误：

未定义#的方法"each_pair“

Answer 1

您正在尝试循环遍历一个哈希数组。

请参阅SO - How do I iterate over an array of hashes and return the values in a single string?上的此示例答案

@max不喜欢我没有发表长篇的解释，所以我将在上面的答案上进行扩展。

irb(main):029:0> o = OpenStruct.new(foo: "bar", bar: "foo")
=> #<OpenStruct foo="bar", bar="foo">
irb(main):032:0> h = Hash.new
=> {}
irb(main):033:0> h[:foo] = "bar"
=> "bar"
irb(main):034:0> h[:bar] = "foo"
=> "foo"
irb(main):035:0> o
=> #<OpenStruct foo="bar", bar="foo">
irb(main):036:0> h
=> {:foo=>"bar", :bar=>"foo"}
irb(main):037:0> o.respond_to?(:each_pair)
=> true
irb(main):038:0> h.respond_to?(:each_pair)
=> true

OpenStructs和哈希都响应@max推荐的方法-在您描述的情况下，使它们在功能上没有什么不同。

irb(main):040:0> one = OpenStruct.new(field: "Out_of_country", operator: "us", values: ["true"])
=> #<OpenStruct field="Out_of_country", operator="us", values=["true"]>
irb(main):041:0> two = OpenStruct.new(field: "Out_of_country", operator: "jp", values: ["true"])
=> #<OpenStruct field="Out_of_country", operator="jp", values=["true"]>
irb(main):042:0> OpenStruct.new(conditions: [one, two])
=> #<OpenStruct conditions=[#<OpenStruct field="Out_of_country", operator="us", values=["true"]>, #<OpenStruct field="Out_of_country", operator="jp", values=["true"]>]>
irb(main):043:0> c = _
=> #<OpenStruct conditions=[#<OpenStruct field="Out_of_country", operator="us", values=["true"]>, #<OpenStruct field="Out_of_country", operator="jp", values=["true"]>]>
irb(main):044:0> hash_one = {field: "Out_of_country", operator: "us", values: ["true"]}
=> {:field=>"Out_of_country", :operator=>"us", :values=>["true"]}
irb(main):045:0> hash_two = {field: "Out_of_country", operator: "jp", values: ["true"]}
=> {:field=>"Out_of_country", :operator=>"jp", :values=>["true"]}
irb(main):046:0> hash_conditions = [hash_one, hash_two]
=> [{:field=>"Out_of_country", :operator=>"us", :values=>["true"]}, {:field=>"Out_of_country", :operator=>"jp", :values=>["true"]}]

irb(main):052:0> hash_conditions.each { |e| puts e[:operator] }
us
jp
=> [{:field=>"Out_of_country", :operator=>"us", :values=>["true"]}, {:field=>"Out_of_country", :operator=>"jp", :values=>["true"]}]
irb(main):053:0> c.conditions.each { |e| puts e[:operator] }
us
jp
=> [#<OpenStruct field="Out_of_country", operator="us", values=["true"]>, #<OpenStruct field="Out_of_country", operator="jp", values=["true"]>]

没有功能上的区别。

Answer 2

如果您只是希望获取OpenStruct的单个属性，则只需在其上调用getter方法：

country = OpenStruct(name: 'Japan', alpha_2: "jp", alpha_3: "jpn")
puts country.name # japan
puts country.alpha_3 # jpn

这就是OpenStruct的全部意义所在。你得到了一个对象，它的行为就像一个类的实例，而实际上没有一个类，也不需要像普通的Struct那样提前定义属性。

您可以使用OpenStruct#each_pair遍历其属性，就像使用散列一样：

os = OpenStruct.new a: 1, b: 2, c: 3
os.each_pair{ |key, value| puts "#{key}: #{value}" }
# Outputs:
# a: 1
# b: 2
# c: 3