相关疑难解决方法(0)

我Cannot iterate over null (null)从下面的查询得到,因为.property_history在result对象中不存在.

.property_history在继续操作之前,如何检查密钥的存在map(...)？

我试过用类似的东西 sold_year= `echo "$content" | jq 'if has("property_history") then map(select(.event_name == "Sold"))[0].date' else null end

原始查询:

sold_year=`echo "$content" | jq '.result.property_history | map(select(.event_name == "Sold"))[0].date'`

JSON:

{  
   "result":{  
      "property_history":[  
         {  
            "date":"01/27/2016",
            "price_changed":0,
            "price":899750,
            "event_name":"Listed",
            "sqft":0
         },
         {  
            "date":"12/15/2015",
            "price_changed":0,
            "price":899750,
            "event_name":"Listed",
            "sqft":2357
         },
         {  
            "date":"08/30/2004",
            "price_changed":0,
            "price":739000,
            "event_name":"Sold",
            "sqft":2357
         }
      ]
   }
}