CODEWITHSUNDEEP
jsonjq
Jan Chavel
Jan Chavel

Reputation: 71

jq: missing JSON object detection

My JSON data:

{
  "Tags": [
           {  "Key": "Team",     "Value": "AA" },
           {  "Key": "Division", "Value": "BB" },
           {  "Key": "Name",     "Value": "CC" }
        ]
}

I'd like to display value of Name ("CC" in example above). If this value is missing "N/A" should be displayed. What I'm looking for is pure jq replacement of this jq and bash mix:

a=$( cat json | jq -r '.Tags[] | select( .Key=="Name" ) | .Value' );
if [ -z $a ]; then a="N/A"; fi
echo $a

Upvotes: 1

Views: 611

Answers (2)

Jan Chavel
Jan Chavel

Reputation: 71

Here is the perfect solution from David Tolnay:

https://github.com/stedolan/jq/issues/976

Quoting it here:

Try this:

jq -r '.Tags | from_entries | .Name // "N/A"'

This converts the list of key/value pairs to a map using from_entries, then picks out the "Name" in the map. Then it uses the "alternative operator" // to produce "N/A" if Name was not in the map.

This requires jq 1.5 in order to understand capitalized "Key" and "Value" in from_entries. If you are stuck on jq 1.4 or older, you need to explicitly convert them to lowercase:

jq -r '.Tags | map({key:.Key, value:.Value}) | from_entries | .Name // "N/A"'

Upvotes: 2

user3899165
user3899165

Reputation:

Use the alternative operator, //.

jq -r '.Tags[] | select(.Key == "Name") | .Value // "N/A"'

Upvotes: 0

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