looping through json object using jq-CodePudding

I have a json file which i have obtained using curl command and it looks as below.

{
  "Storages": [
    {
      "Creation": "2020-04-21T14:01:54",
      "Modified": "2020-04-21T14:01:54",
      "Volume": "/dev/null",
      "id": 10000,
      "version": "20190925-230722"
    },
    {
      "Creation": "2020-04-22T14:01:54",
      "Modified": "2020-04-22T14:01:54",
      "Volume": "/opt/home",
      "id": 10001,
      "version": "22a-20190925-230722"
    },
    {
      "Creation": "2020-04-23T14:01:54",
      "Modified": "2020-04-23T14:01:54",
      "Volume": "/home/abcd",
      "id": 10003,
      "version": "21c-20190925-230722"
    }
  ]
}

Now I need to form another json by looping through above json array and get the keys (id and voulme) from each array if version starts with 21a.

CodePudding user response：

You can use startswith builtin function such as

jq -r '.Storages[] | select(.version | startswith("21a")) | {id: .id, Volume: .Volume}'

Demo

CodePudding user response：

For educational purposes, here's a jq command that does both the things you want, but in 2 separate steps:

jq -r 'del(.Storages[] | select(.version | startswith("21a") | not))
       .Storages[] | {id, version}'

The first part (del(.Storages[] | select(.version | startswith("21a") | not))) filters out the array elements that don't have a version starting with 21a. The second part (.Storages[] | {id, version}) drills and extracts the specific information you need.