Convert json data to comma separated string

Question

I have a json object that has an unknown number of variables, like this:

{ 
 "var1": 123, 
 "var2": 456, 
 "var3": 789 
}

How can I automatically convert it to form the following string?

'var1=123,var2=456,var3=789'

Note, I am looking for a solution that doesn't require installing jq.

• terdon: Will it always be this simple? Exactly one set of { }, then pairs of quoted string with no spaces, an :, one space, numbers and a comma?
• teeeeee: @terdon Yes it will.
• NickD: jq is a versatile tool - see e.g. stackoverflow.com/questions/32960857/… for some possibilities.
• steeldriver: Miller might be even easier, since the output you want appears to be in exactly the default DKVP format. So it could be as simple as mlr --ijson cat input.json .
• Kusalananda: Without installing jq: docker run -i --rm ghcr.io/jqlang/jq -r 'to_entries | map("\(.key)=\(.value)") | "'\''\(join(","))'\''"' <file

Answer 1

If you don't care about the order of the object members:

$ perl -CO -MJSON::PP -l -0777 -ne '
 $j = decode_json($_);
 print join ",", map("$_=$j->{$_}", keys %$j)' your-file
var3=789,var2=456,var1=123

perl comes pre-installed on most systems, and JSON::PP is one its built-in modules.

Or if your system has python3:

PYTHONIOENCODING=utf-8 python3 -c '
import json, sys;
_ = json.load(sys.stdin);
print(",".join(map(lambda i: "%s=%s" % i, _.items())))' < your-file

(the order should be preserved as python3's dictionaries contrary to perl's hashes do keep track of an order of keys).

With a less tamed input such as:

{
 "var-\"x\"": 1e-2,
 "var=v,v": "\n",
 "var\uD83E\uDDD9": null
}

They give

var=v,v=
,var-"x"=0.01,var🧙=

And

var-"x"=0.01,var=v,v=
,var🧙=None

Respectively, while mlr --ijson cat gives:

var-"x"=1e-2,var=v,v=
,var🧙=null

And jq -r 'to_entries|map("\(.key)=\(.value)")|join(",")' gives:

var-"x"=0.01,var=v,v=
,var🧙=null

(though neither jq nor mlr are generally installed by default).

• kos: Any reason why you're not just sorting the keys, as in print join ",", map"$_=$j->{$_}", sort keys %$j?
• Stéphane Chazelas: @kos, sounds like the var1, var2 in the sample are just placeholders for the actual values. While sorting the keys lexically here (which could also be done using the canonical JSON:PP option) would happen to restore the original order in the sample, it wouldn't in the general case.
• kos: Ok, I see the point, thanks (obviously you know and just got confused in the comment but for others: canonical only works while encoding, once the keys are stored into a hash the order is lost no matter what, so sorting would be needed in order to sort the values in the output)
• Stéphane Chazelas: @kos, ah yes, sorry, canonical wouldn't help indeed as we're not encoding. Thanks for the correction.

Answer 2

If it will always be this simple, something like this might work

tr : = | tr -d '{}"\n ' | sed -e "s/^/'/" -e "s/$/'/"

In parts:

• translate : to =
• remove all other extra characters including punctuation, spaces, newlines
• add single quote at start and end

• Vilinkameni: What if the variables are strings, which might contain {} etc?
• teeeeee: @Vilinkameni This is not the case in my application. There will be no special characters like that in the strings. The answer provided works perfectly for me.
• user10489: This is the simplest answer. It's not the best answer. OP said it would always be simple, so there are a lot of cases this won't work for. I like the other answers. I'm disappointment (but not surprised) there isn't a shorter answer.

Answer 3

One option to do this with awk will looks like:

awk '!/{/ && !/}/ {gsub("\"","");gsub(":","=");gsub(" ","");printf "%s",0ドル}' input_file

This command expect { and } to be the only symbols on the line and the rest of the format to be strict

If you want to have new line at the end you can use command:

awk '!/{/ && !/}/ {gsub("\"","");gsub(":","=");gsub(" ","");printf "%s",0ドル} END {printf "\n"}' input_file