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From: Alex R <[email protected]>
To: pgsql-novice <[email protected]>
Subject: Re: JSONpath query that returns paths to the matches
Date: Mon, 20 Dec 2021 01:19:43 +0100
Message-ID: <CANK1NR2=WvSBRAL=HKsZUHyoK_uTZKajwoE-bC=Q2GNHzSkv0g@mail.gmail.com> (raw)
In-Reply-To: <CAKFQuwYVhCVwa0qfTfpvkziLnj_ogdpGruJhFqJ=Zig=n2+LuA@mail.gmail.com>
References: <CANK1NR1E1CyHcqF+xQvBYBY0+G4GGL_HKDDSad2am74zz_N3mg@mail.gmail.com>
	<CAKFQuwYVhCVwa0qfTfpvkziLnj_ogdpGruJhFqJ=Zig=n2+LuA@mail.gmail.com>

Hi David,

Thank you for the swift reply. After ruling out the option of doing that by
leveraging JSONPath, I took a different approach and wrote a function
in pl/pgsql
that does not need these paths at all. I could deviate a bit, because I had
some wiggle room in the context of the bigger problem I was working on.


For others who might be confronted with a similar problem in the future,
here is a minimal example that uses Python and a library called jsonpath_ng,
which tells you what the match is and where it occurs:

```
# pip install jsonpath_ng

import json
from jsonpath_ng import jsonpath, parse

raw = '''{
  "this": "that",
  "that": [{"x": "aaa"},{"y": "missed"}],
  "nested": {
        "deep": {
        "x": "bbb"
      }
  }
}'''

data = json.loads(raw)
query = parse('$..x')

results = query.find(data)
for entry in results:
    print(f'{entry.full_path} -> {entry.value}')

# that.[0].x -> aaa
# nested.deep.x -> bbb
```

Porting this to pl/python is left as an exercise for the reader :-)

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