How to check for null or empty in jq and substitute for empty string in jq transformation

问题

How to check for null or empty in jq and substitute for empty string in jq transformation.

Example in below JSON, this is the JQ

JQ:

   .amazon.items[] | select(.name | contains ("shoes")) as $item |
   {
        activeItem: .amazon.activeitem,
        item : {
         id : $item.id,
         state : $item.state,
         status : if [[ $item.status = "" or $item.status = null ]]; 
        then 'IN PROCESS' ; else $item.status end
         }  
   }

JSON:

  {
    "amazon": {
      "activeitem": 2,
      "items": [
        {
          "id": 1,
          "name": "harry potter",
          "state": "sold"
        },
        {
          "id": 2,
          "name": "adidas shoes",
          "state": "in inventory"
        },
        {
          "id": 3,
          "name": "watch",
          "state": "returned"
        },{
          "id": 4,
          "name": "Nike shoes",
          "state": "in inventory"
        }
      ]
    }
  } 

I want to add a default string "In Process" if the status is empty or Null.

Based on Item condition, using the query below and take the first object from the filtered results.

code .amazon.items[] | select(.name | contains ("shoes")) code

Expected Output:

{
    "activeitem": 2,
    "item": {
      "id": 2,
      "name": "adidas shoes",
      "state": "in inventory",
      "status": "IN PROCESS"
    }
  }

回答1:

The key here is to use |=:

.amazon.item.status |=
  if . == null or . == ""
  then "IN PROCESS"
  else .
  end

来源：https://stackoverflow.com/questions/54332521/how-to-check-for-null-or-empty-in-jq-and-substitute-for-empty-string-in-jq-trans