Use jq to parse a JSON String

Question

I'm trying to get jq to parse a JSON structure like:

{
  "a" : 1,
  "b" : 2,
  "c" : "{\"id\":\"9ee ...\",\"parent\":\"abc...\"}\n"
}

That is, an element in the JSON is a string with escaped json.

So, I have something along the lines of $ jq [.c] myFile.json | jq [.id]

But that crashes with jq: error: Cannot index string with string

This is because the output of .c is a string, not more JSON. How do I get jq to parse this string?

My initial solution is to use sed to replace all the escape chars (\":\", \",\" and \") but that's messy, I assume there's a way built into jq to do this?

Thanks!

edit: Also, the jq version available here is:

$ jq --version
jq version 1.3

I guess I could update it if required.

Answer 1

jq has the fromjson builtin for this:

jq '.c | fromjson | .id' myFile.json

fromjson was added in version 1.4.

Answer 2

You can use the raw output (-r) that will unescape characters:

jq -r .c myfile.json | jq .id

ADDENDUM: This has the advantage that it works in jq 1.3 and up; indeed, it should work in every version of jq that has the -r option.