Regex to match specific key in a JSON list

Question

I work with Json looks something like below

[
    {
      "accessType": "*",
      "principalType": "ROLE",
      "principalId": "$unauthenticated",
      "permission": "DENY"
    },
    {
      "accessType": "*",
      "principalType": "ROLE",
      "principalId": "everyone",
      "permission": "Allow"
    },
    {
      "accessType": "*",
      "principalType": "ROLE",
      "principalId": "$owner",
      "permission": "ALLOW"
    }
  ]

I would like to change the access type to "restricted" instead of "*" for the PrincipalID: "everyone"... I am using something like sed '\{[^}]*?everyone[^}]*\},s,"accessType": "*","accessType": "Restricted",' sdcard/etc/sample.json but it doesnt work. it has to look like below:

{
      "accessType": "Restricted",
      "principalType": "ROLE",
      "principalId": "everyone",
      "permission": "Allow"
    },

it is a continuation to the previous question: Regex to match specific, multiline object in JSON list

I cannot use any 3rd party applications to perform this action, only using sed and regex or any 1 liner unix command

You should generally not try to use regex to parse JSON. Use the right tool for the job (probably not Sed). Use a JSON parser. — Tim Biegeleisen
– Tim Biegeleisen, Commented Nov 2, 2020 at 15:55

choroba · Accepted Answer · 2020-11-02 16:12:45Z

1

sed is not the right tool for the job. Use jq, a JSON-aware tool that can parse JSON even if its formatting changes.

jq '.[] |= (if .principalId == "everyone"
            then (.accessType |= "restricted")
            else . end)' \
    file.json

answered Nov 2, 2020 at 16:12

choroba

245k27 gold badges221 silver badges304 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Casper Dijkstra · Accepted Answer · 2020-11-02 23:57:33Z

1

You can use a JSON parser for this, like jq.

I put your json in a file (called jsonfile below) and can obtain your desired result like

$ cat jsonfile | jq. '.[0]'.   // OR jq '.[0]' jsonfile
{
  "accessType": "*",
  "principalType": "ROLE",
  "principalId": "everyone",
  "permission": "Allow"
}
// also works for .[1] and .[2]

Now I adjust the right json field like this:

$ jq '.[].accessType = "Restricted"' jsonfile
[
  {
    "accessType": "Restricted",
    "principalType": "ROLE",
    "principalId": "$unauthenticated",
    "permission": "DENY"
  },
  {
    "accessType": "Restricted",
    "principalType": "ROLE",
    "principalId": "everyone",
    "permission": "Allow"
  },
  {
    "accessType": "Restricted",
    "principalType": "ROLE",
    "principalId": "$owner",
    "permission": "ALLOW"
  }
]

and I can grep the first JSON list with a pipe:

$ jq '.[].accessType = "Restricted"' jsonfile | jq '.[0]'
{
  "accessType": "Restricted",
  "principalType": "ROLE",
  "principalId": "$unauthenticated",
  "permission": "DENY"
}

edited Nov 2, 2020 at 23:57

answered Nov 2, 2020 at 16:11

Casper Dijkstra

1,9132 gold badges18 silver badges41 bronze badges

1 Comment

Casper Dijkstra Over a year ago

A small improvement would be to use one jq command (which I think should be possible), but jq '.[0] | fromjson | .[].accessType = "Restricted"' jsonfile' gives an error that only strings can be parsed... Working on it

MonkeyZeus · Accepted Answer · 2020-11-02 16:16:42Z

-1

Assuming you are sticking to this basic and known JSON structure and assuming SED supports a lot of PCRE syntax then this would work:

(\{[^}]+"accessType": ")(\*)(",[^}]+"principalId": "everyone",[^}]+\})

https://regex101.com/r/xt6DY9/1/

answered Nov 2, 2020 at 16:16

MonkeyZeus

20.8k4 gold badges41 silver badges83 bronze badges

1 Comment

Ryszard Czech Over a year ago

This pattern is POSIX ERE compliant, but that means OP must know how to enable it and how to properly quote the sed command.

Collectives™ on Stack Overflow

Regex to match specific key in a JSON list

3 Answers 3

Comments

1 Comment

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related