您可以使用dig方法。如果任何中间步骤是nil，它将返回nil。

appointment_id = data.dig('eventData','appointmentId')
#=> 48761

site_id = data.dig('eventData','siteId')
#=> 232

然后

if site_id && appointment_id
  # do_something
end

您可以显式检查您希望存在的属性，然后一次性设置var和过程：

data = params['eventData']

if data && data['siteId'] && data['appointmentId']
  siteID = data['siteId']
  appointmentID = data['appointmentId']
  # process this
end

另一种选择是将if语句结果保存到它自己的var中，然后将其用作处理的条件：

data = params['eventData']

process = if data.present?
  siteID = data['siteId']
  appointmentID = data['appointmentId']
end

if process
  # process this
end

或者另一个选择是将vars设置为内联：

data = params['eventData']

if data && siteID = data['siteId'] && appointmentID = data['appointmentId']
  # process here
end

我们可以编写以下方法：

def extract(schedule)
  siteId,appointmentId = 
    schedule["eventData"]&.values_at("siteId","appointmentId")
end

如果schedule没有键"eventData"，则sideId和appointentId都被赋值为nil。如果schedule确实有密钥"eventData"，则我假设schedule["eventData"]是一个散列，并且：

siteId = schedule["eventData"]["siteId"]
appointmentId = schedule["eventData"]["appointmentId"]

&是safe navigation operator，它在Ruby v2.3中首次亮相。另请参见Hash#values_at。

此方法的用法如下。

def doit(schedule)
  siteId,appointmentId = extract(schedule)
  if siteId && appointmentId
    # do something
  else
    # do something else
  end
end

以下是extract返回的值的一些示例：

schedule = { "eventData"=>{ "siteId"=>232,"appointmentId"=>48761 } }
siteId,appointmentId = extract(schedule)
  #=> [232,48761] 
siteId
  #=> 232 
appointmentId
  #=> 48761 

schedule = { "eventData" => { "siteId" => 232 } }
siteId,nil] 

schedule = { "eventData" => {} }    
siteId,appointmentId = extract(schedule)
  #=> [nil,nil]