sh: How to write an array to a json file using jq

Question

How can I write the array to a json file?

#!/bin/sh
declare -A myarray 
myarray["testkey"]="testvalue"
myarray["testkey1"]="testvalue1"
myarray["testkey2"]="testvalue2"

jq -n --arg $myarray[@] > file.json

EDIT:

The json file should contain the following:

{
  "testkey": "testvalue",
  "testkey1": "testvalue1", 
  "testkey2": "testvalue2"
}

I wrote an answer and only then stumbled on this, which is a pretty close duplicate: stackoverflow.com/questions/44792241/… It has a little bit extra around parsing integers but otherwise it's the same. — Weeble
– Weeble, Commented Oct 30, 2020 at 13:44
Does this answer your question? Constructing a json hash from a bash associative array — Weeble
– Weeble, Commented Oct 30, 2020 at 13:45

Weeble · Accepted Answer · 2020-10-30 13:43:05Z

1

Here's a way that doesn't need an extra step before to serialise the associative array:

jq -n '
    $ARGS.positional|
    . as $a|
    (length/2) as $l|
    [range($l)|{key:$a[.],value:$a[.+$l]}]|
    from_entries' --args "${!myarray[@]}" "${myarray[@]}"

It should work even with newlines in the keys or values. The one caveat is that technically bash doesn't guarantee that ${!myarray[@]} will output the keys in the same order that ${myarray[@]} will output the values. It does do that in practice, and it's hard to imagine an implementation that wouldn't, but if you really want to be safe here's a variation on Inian's answer that should be safe to newlines. It also assembles a single object.

for key in "${!myarray[@]}"; do 
    printf "%s\0%s\0" "$key" "${myarray[$key]}"
done | 
jq -sR '
    split("\u0000")|
    . as $elements|
    [range(length/2)|{key:$elements[2*.],value:$elements[2*.+1]}]|
    from_entries'

answered Oct 30, 2020 at 13:43

Weeble

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1 Comment

Inian Over a year ago

Nice! but do add a note $ARGS.positional is a jq-1.6 thingy

vgersh99 · Accepted Answer · 2020-10-29 16:09:10Z

0

as an alternative to jq:

#!/bin/sh
declare -A myarray
myarray["testkey"]="testvalue"
myarray["testkey1"]="testvalue1"
myarray["testkey2"]="testvalue2"

cols=$(printf "%s," "${!myarray[@]}")
column -J --table-name 'myTable' --table-columns "${cols}"  <<<"${myarray[@]}"

answered Oct 29, 2020 at 16:09

vgersh99

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