I’m trying to identify object elements which a key starting with @t. My goal is to delete them from the object all together.

Example Input

{
  "process_state": {
    "@user_id": "john smith",
    "@t39ee396f50": 1,
    "@t375b0311e8": 1,
    "@t12dd92bf45": 1
     }
}

Expected Output

{
  "process_state": {
    "@user_id": "john smith",
     }
}

I’ve tried using jq and jtc to accomplish this and both seem to struggle with the leading @ symbol. I’m assuming it’s a format issue with my code. Can I use wildcards? I’ve tried a couple methods with no luck.

JQ

jq ‘. |= map(select(. | contains("@t") | not))’

Error: and string ("@t") cannot have their containment checked

JTC

<file jtc -w'<process_state.@t*>l:’

No error but @t* fields still exist in json object.

Any help is much appreciated.

>Solution :

We’re going to use test("^@t") instead of contains("@t") since we want to check for a leading @t. But that’s not why you are getting that error. You have the wrong object on the left-hand side of |=, and map doesn’t do what you think for objects.

Two solutions:

• Using filtering (like you were attempting):

  .process_state |= with_entries(
     select( .key | test("^@t") | not )
  )
  

  Demo on jqplay

• Using deletion:

  .process_state |= del(
     .[
        keys_unsorted[] |
        select( test("^@t") )
     ]
  )
  

  Demo on jqplay