Question

有三个哈希。每个哈希都会产生一个键/值对。

当合并并输出到json文件时，唯一可见的k / v对是带数据的那些。

例如：

employee_hours[ name ] =         {"Hours" => hours}
employee_revenue [ name ] =      {"Revenue" => revenue}
employee_activations [ name ] =  {"Activations" => activations}

如果任何k / v对不存在，我需要将它们包含在输出中，其值为0.00。

我试图简单地在每个哈希表中包含来自其他哈希值的空k / v对，但是当合并时，它们会覆盖现有值。

employee_hours[ name ] =         {"Hours" => hours, "Revenue" = "", Activations = ""}
employee_revenue [ name ] =      {"Hours" => "", "Revenue" => revenue, Activations = ""}
employee_activations [ name ] =  {"Hours" => "", "Revenue" => "", "Activations" => activations}

修改

我目前的代码列在此处：https://gist.github.com/hnanon/766a0d6b2b0f9d9d03fd

Answer 1

您需要为默认值定义哈希并合并到其中。假设employee_final是您合并所有员工信息的哈希，

employee_defaults = { "Hours" => 0.0, "Revenue" => 0.0 }
employee_final.each_key do |name|
  employee_final[name] = employee_defaults.merge(employee_final[name])
end

Answer 2

听起来好像你需要定义一个'REQUIRED_KEYS'数组，并在哈希中添加检查它们的存在。这是实现这一目标的一种方法：

REQUIRED_KEYS = [ "A", "B", "C" ]
DEFAULT_VALUE = 0.0    
REQUIRED_KEYS.each { |key| your_hash[key] = DEFAULT_VALUE if not your_hash.has_key?(key) }

Answer 3

使用哈希默认值

您可以使用Hash#new的参数来设置哈希的默认值。例如：

require 'json'

employee_hours       = Hash.new(0.0)
employee_revenue     = Hash.new(0.0)
employee_activations = Hash.new(0.0)

name = 'Bob'

{
  'Hours'       => employee_hours[name],
  'Revenue'     => employee_revenue[name],
  'Activations' => employee_activations[name],
}.to_json

# => "{\"Hours\":0.0,\"Revenue\":0.0,\"Activations\":0.0}"

合并哈希时包括空k / v对

3 个答案:

使用哈希默认值