Ruby on rails Ruby：如何迭代散列并根据项目的数量做一些不同的事情？

我正在处理一个如下所示的哈希：

h = {
    "side1"=>["green", "Green"], 
    "side2"=>["verde", "Verde"]
}

h = {
    "side1"=>["green", "Green"], 
    "side2"=>["verde", "Verde"]
}
h.map { |k,v| "#{k} from #{v[0]} to #{v[1]}" }.join(' and ')
# "side1 from green to Green and side2 from verde to Verde"

h = { 
    "side2"=>["verde", "Verde"]
}
h.map { |k,v| "#{k} from #{v[0]} to #{v[1]}" }.join(' and ')
# side2 from verde to Verde"

但是，其中可能只有一项：

h = { 
    "side2"=>["verde", "Verde"]
}

我想输出散列，使其看起来像这样：

h = {
    "side1"=>["green", "Green"], 
    "side2"=>["verde", "Verde"]
}

h = {
    "side1"=>["green", "Green"], 
    "side2"=>["verde", "Verde"]
}
h.map { |k,v| "#{k} from #{v[0]} to #{v[1]}" }.join(' and ')
# "side1 from green to Green and side2 from verde to Verde"

h = { 
    "side2"=>["verde", "Verde"]
}
h.map { |k,v| "#{k} from #{v[0]} to #{v[1]}" }.join(' and ')
# side2 from verde to Verde"

用户将side1从绿色更改为绿色，将side2从verde更改为绿色

当有两个项目时，将从“和”中分离。否则它将如下所示：

h = {
    "side1"=>["green", "Green"], 
    "side2"=>["verde", "Verde"]
}

h = {
    "side1"=>["green", "Green"], 
    "side2"=>["verde", "Verde"]
}
h.map { |k,v| "#{k} from #{v[0]} to #{v[1]}" }.join(' and ')
# "side1 from green to Green and side2 from verde to Verde"

h = { 
    "side2"=>["verde", "Verde"]
}
h.map { |k,v| "#{k} from #{v[0]} to #{v[1]}" }.join(' and ')
# side2 from verde to Verde"

用户将side2从verde更改为verde

---

这一切都发生在我的rails视图脚本中。我如何编写代码才能做到这一点？

您可以这样做：

h = {
    "side1"=>["green", "Green"], 
    "side2"=>["verde", "Verde"]
}

h = {
    "side1"=>["green", "Green"], 
    "side2"=>["verde", "Verde"]
}
h.map { |k,v| "#{k} from #{v[0]} to #{v[1]}" }.join(' and ')
# "side1 from green to Green and side2 from verde to Verde"

h = { 
    "side2"=>["verde", "Verde"]
}
h.map { |k,v| "#{k} from #{v[0]} to #{v[1]}" }.join(' and ')
# side2 from verde to Verde"

因此，雇员再培训局认为：

用户已更改。

如果您经常做这种事情，那么您可能需要为它构建一个助手

由于您在Rails中，因此也可以使用：

用户已更改。

to_句子

方法也可以更好地扩展到两个以上的元素。因此，如果您还有

“side3”=>[“pancakes”，“pancakes”]

，那么您将得到：

用户将side1从绿色更改为绿色，side2从verde更改为verde，side3从煎饼更改为煎饼。

这里有一个可能的解决方案：

hash = {
    "side1"=>["green", "Green"], 
    "side2"=>["verde", "Verde"]
}

result = hash.map do |key,value|
  "#{key} from #{value.first} to #{value.last}"
end

puts "User changed #{result.to_sentence}"

输出将是：

User changed side1 from green to Green and side2 from verde to Verde

而如果仅添加了一项：

User changed side1 from green to Green

---

+1对于to_句，我不知道这样的事情也存在。Rails提供了您所需的一切：）