Bash JSON processing - How to test if all objects in array have satisfied condition

Question

I'm trying to write a bash function that would parse a json response and assert if an array of objects all satisfy some condition, but I'm getting nowhere with testing that state.

Exemplary JSON after initial transformations:

[
  {
    "key": "Org1",
    "value": true
  },
  {
    "key": "Org2",
    "value": false
  }
]

The condition is to have all elements (no matter the length of the array) to have value == true.

I'm doing the JSON transformations using jq, but I have no idea how to either store the result in a bash var so I could loop throw the elements or reduce the array to a single value that I could parse directly in an if statement.

Could anyone help?

echo "$json" | jq 'all(.value)' tests the value property of each object in the array are true. — glenn jackman
– glenn jackman, Commented Oct 28, 2020 at 17:10

chepner · Accepted Answer · 2020-10-29 12:20:15Z

2

You can use the all function to reduce an array of Booleans* to true if all the Booleans are true. jq will output that value, which you can capture using command substitution.

result=$(jq 'map(.value) | all' tmp.json)

You may not need the actual output, though. It may be sufficient to use the --exit-status option (short form -e) to test if jq would return true or not.

if jq -e 'map(.value) | all' tmp.json > /dev/null; then
   echo "All were true"
else
   echo "At least one was false"
fi

* Among other things; see @peak's comment below

edited Oct 29, 2020 at 12:20

answered Oct 28, 2020 at 17:11

chepner

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2 Comments

peak Over a year ago

Technically, and the documentation notwithstanding, the all family of filters uses truthiness rather than true as the criterion. Consider e.g. all(1;.) #=> true ; all(nan;.) #=> true ; all(empty;.) #=> true ; all(null;.) #=> false ;

Sniady Over a year ago

Holy cow, I did not see this all function. Thank you very much for that one!

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