CODEWITHSUNDEEP
jsonbashkeyjq
jado
jado

Reputation: 104

jq pass argument as a key to new field

I'm trying to add new field in a json file using jq:

jq -r --arg k "foo" --arg v "bar"  '.newField += {$k:$v}' myfile

But it results in:

jq: error: syntax error, unexpected ':', expecting '}' (Unix shell quoting issues?) at <top-level>, line 1:
.newField += {$k:$v}                
jq: error: May need parentheses around object key expression at <top-level>, line 1:
.newField += {$k:$v}              
jq: 2 compile errors

When I remove key variable like below it works fine:

jq -r --arg k "foo" --arg v "bar"  '.newField += {"static_key":$v}' myfile

Any idea how to use key name from jq arg?

Upvotes: 3

Views: 2633

Answers (2)

michael
michael

Reputation: 9749

If this helps, using the following uses the arg var itself as json key, and the arg value as the json value:

$ jq -r --arg foo "bar"  '.newField += {$foo}' myfile
....
"newField": {
    "foo": "bar"
}

Upvotes: 2

David Z
David Z

Reputation: 131550

As the error message suggests, put parentheses around the key:

jq -r --arg k "foo" --arg v "bar"  '.newField += {($k):$v}' myfile

jq requires keys given by expressions (i.e. not literal strings) to be parenthesized (noted in the manual).

Upvotes: 7

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