CODEWITHSUNDEEP
javascriptjsonshelljq
krckumar
krckumar

Reputation: 544

How to perform JSON object updates using jq commandline utility

I have a JSON object as follows

{"Sample" : [{ "key": "KeyName", "values": [ [1025409600000, 10], [1028088000000, -6.3382185140371] ] }]}

Using javascript I can modify any values as follows

data.Sample[0].values.push([1028088000000,0]);

How to perform the similar operation using jq commandline json processor? So the JSON object becomes

{"Sample" : [{ "key": "KeyName", "values": [ [1025409600000, 10], [1028088000000, 0] ] }]}

Thank you.

Upvotes: 0

Views: 115

Answers (1)

peak
peak

Reputation: 116750

As it stands there is a bug in the question, as Javascript's Array.push appends to an array.

The jq equivalent of the given expression:

data.Sample[0].values.push([1028088000000,0]);

would be:

.Sample[0].values += [[1028088000000,0]]

or if you want to use the Javascript syntax, you could define def push(x): .[length] = x;

If you want to replace the last value in the values array by another value, say $x, you could (using jq 1.5 or later) write:

.Sample[0].values[-1] = $x

A more robust (with respect to different jq releases) approach would be:

.Sample[0].values |= (.[length-1] = $x)

With jq 1.5 or later, if you wanted only to change the negative number to 0, you would write:

    .Sample[0].values[-1][-1] = 0

Etc.

Upvotes: 2

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