I have a json file: example.json

{
  "list": [
    {
      "entryA": {
        "item1": "foo",
        "item2": "bar"
      }
    },
    {
      "entryB": {
        "item1": "oof",
        "item2": "rab"
      }
    }
  ]
}

I would like the output to be the contents of entryB:

{
  "item1": "oof",
  "item2": "rab"
}

however, using the example from the manual for Optional Object Identifier-Index: .foo?, I get these results:

$ jq '.list[] | .entryB?' example.json
null
{
  "item1": "oof",
  "item2": "rab"
}

$ jq '.list[] | .["entryB"]?' example.json
null
{
  "item1": "oof",
  "item2": "rab"
}

How can I format the JQ Query to not include a null output for entryA?

CodePudding user response：

By using the alternative operator // you can defect to empty if the first alternative does not exist.

jq '.list[] | .entryB // empty' example.json

{
  "item1": "oof",
  "item2": "rab"
}

Demo

CodePudding user response：

One option would be using to_entries such as

jq '.list[] | to_entries[] | select(.key=="entryB") | .value' example.json