How can I extract specific lines from a json document?

Question

I have a json file with thousands of lines and 90 json objects. Each object come with the following structure:

{
        "country_codes": [
            "GB"
        ],
        "institution_id": "ins_118309",
        "name": "Barclaycard (UK) - Online Banking: Personal", // I want to extract this line only
        "oauth": true,
        "products": [
            "assets",
            "auth",
            "balance",
            "transactions",
            "identity",
            "standing_orders"
        ],
        "routing_numbers": []
    },

For the ninety objects, I would like to delete all the lines and keep only the one with the name of the institution.

I guess that I will have to use a regex here? I'm happy to use with vim, sublime, vscode or any other code editor that will alow me to do so

How can I extract these lines so I will stay with the following 90 lines?

 "name": "Barclaycard (UK) - Online Banking: Personal",
 "name": "Metro Bank - Commercial and Business Online Plus",
 ...
 ...

 "name": "HSBC (UK) - Business",

Assuming you aren't particular about the formatting, you should use something like `jq` to write the filtered objects to a new file, then replace the old with the new. — chepner, Sep 12 '22 at 18:42
If you want to copy those lines, just do `:sort`, search for a known word `/Baclay`, yank `Vjjjjjy` and finally `u` to undo — balki, Sep 29 '22 at 19:30

mattb · Accepted Answer · 2022-09-15T07:25:31.817

If you must use a code editor, then in Vim you can delete all lines not matching a pattern with: :v/^\s*"name":/d

The above pattern says:

^ line begins with
\s* zero or more white spaces
"name:" (pretty explanatory)

Although it's better to use a dedicated tool for parsing json files rather than regex as json is not a 'regular language'.

Bonus

If you do end up doing it in Vim, you can finish up by left align all the lines, do :%left or even just :%le.

romainl · Answer 2 · 2022-09-13T06:59:55.243

That doesn't sound like the job for a text editor or even for regular expressions. How about using the right tool for the job™?

# print only the desired fields to stdout
$ jq '.[] | .name' < in.json

# write only the desired fields to file
$ jq '.[] | .name' < in.json > out.json

See https://stedolan.github.io/jq/.

If you really want to do it from a text editor, the simplest is still to filter the current buffer through a specialized external tool. In Vim, it would look like this:

:%!jq '.[] | .name'

See :help filter.

FWIW, here it is with another right tool for the job™:

:%!jj \\#.name -l

See https://github.com/tidwall/jj.

score 1 · Answer 3 · edited Sep 12 '22 at 16:21

1

you can use grep eventually :

grep '^\s*"name":' your_file.json

edited Sep 12 '22 at 16:21

mattb

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answered Sep 12 '22 at 16:16

Julien

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rioV8 · Answer 4 · 2022-09-12T17:28:01.977

0

In VSC

select institution_id
execute Selection > Select All Occurenses
Arrow Left
Ctrl+X
Esc
Ctrl+V

edited Sep 12 '22 at 17:28

answered Sep 12 '22 at 16:24

rioV8

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It's not clear which editor/software these instructions are for. – mattb Sep 12 '22 at 16:37

score 0 · Answer 5 · answered Sep 12 '22 at 18:27

In vscode (although I would think it is the same for any regex-handling editor), use this Find:

^(?!\s*"name":.*).*\n?|^\s*

and replace with nothing. See regex101 demo.

^(?!\s*"name":.*).*\n? : get all lines that are not followed by "name":... including the newline so that line is completely discarded.

^\s* gets the whitespace before "name":...... - also discarded since we are replacing all matches with nothing.

score 0 · Answer 6 · answered Sep 12 '22 at 19:22

Parsing JSON in Vim natively:

call getline(1, '$')
    \ ->join("\n")
    \ ->json_decode()
    \ ->map({_, v -> printf('"name": "%s",', v.name)})
    \ ->append('$')

NB. Line continuation is only available when sourcing script from file. If run interactively then type command on a single line.

How can I extract specific lines from a json document?

6 Answers6

Bonus