JSON parsing [`jq`]: Get value of grandparent’s sibling

Question

Example

{
  "gp_sibling": "desired_value",
  "grand-parent": {
    "parent": [
      {
        "key": "known_value",
        "sibling": "asdf"
      }
    ]
  }
}

Problem definition

I have a large JSON. I know that key has a unique value. I need to get it’s grand-parent’s sibling key value (the value of gp_sibling key).

Now, I could grep the JSON, but I’d like to use jq. But I don’t know to achieve this (I use jq for simple queries only).

Notes

Although I know that jq can be used on Windows too, I use it on Linux only.

Post updates

Removed commas from the example. Some formatting fixes.

dan1st · Accepted Answer · 2020-01-19T19:19:15.007

0

If you just want to get the element gb_sibling, you could use the following:

jq .gp_sibling <file>

If you want to get it only if there is the key element with it's value, you could try this:

jq 'select(."grand-parent"?.parent?[]?.key=="known_value")|.gp_sibling' <file>

This, it filters the elements where the content of the attribute key inside parent inside grand-parent equals known_value.

From that result, gp_sibling is selected.

[NOTE]

grand-parent is quoted because the dash would cause problems otherwise.

edited Jan 19 '20 at 19:19

answered Jan 19 '20 at 18:50

dan1st

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1

I think he would like to extract the value of gp_sibling. | jq '.gp_sibling' | should be enough (tested here https://jqplay.org/#) – Marco Massetti Jan 19 '20 at 18:59
1

@MarcoMassetti You're right. I've edited the answer. – dan1st Jan 19 '20 at 19:05
Perfect! @dan1st, your solution works with the provided example, but I cannot make it work with the original key names ([example #2](https://jqplay.org/s/2VOZHwNn10)). There is an error: `jq: error: syntax error, unexpected INVALID_CHARACTER, expecting $end (Unix shell quoting issues?) at , line 1:`. Can you help me out here please? – tukusejssirs Jan 19 '20 at 19:33
1

@tukusejssirs this is because of the web UI. You should only put the thing inside the `'...'` in `filter`, not the whole command. – dan1st Jan 19 '20 at 19:36
Okay. I had blank output with the non-disclosed data until I added `.[]` (I missed that that whole data was square-bracketed). So in in the end, I used `[some_command] | jq -r '.[] | select(."grand-parent"?.parent?[]?.key=="known_value") | .gp_sibling'` – tukusejssirs Jan 19 '20 at 19:45
Yes, everything works now as expected. Thank you very much. :) – tukusejssirs Jan 19 '20 at 19:48
Great @dan1st :) – Marco Massetti Jan 20 '20 at 08:30

score 0 · Answer 2 · answered Jan 19 '20 at 19:43

My reading of the question is that none of the key names except "key" is to be used in the query, and that if there were more than one "grand-parent sibling" that was a string, we'd want them all.

paths(.key? == "known_value") as $p
| getpath($p[0:-4])
| .[]
| select(type=="string")

JSON parsing [`jq`]: Get value of grandparent’s sibling

Example

Problem definition

Notes

Post updates

2 Answers2