combine array of objects from two files with jq under specific key 1.4

Question

I have two files with the following JSON that I need to combine using the relative array position of each object:

PS: - I am restricted to version 1.4 as am on Solaris so don't have the [inputs] feature

File 1

{ "input": [ { "email": "[email protected]", "firstName": "Fred" }, { "email": "[email protected]", "firstName": "James" } ] }

File 2:

{ "result": [ { "id": 50, "status": "created" }, { "id": 51, "status": "rejected" } ] }

the expected result is the elements of input[1] combined with elements of result[1] and so on as follows:

{ "combined": [ { "email": "[email protected]", "firstName": "Fred", "id": 50, "status": "created" }, { "email": "[email protected]", "firstName": "James", "id": 51, "status": "rejected" } ] }

Hello, Paolog, do you remember that it is good to mark an answer as accepted if it helped you? — Michał Politowski
– Michał Politowski, Commented Mar 2, 2019 at 8:15

Michał Politowski · Accepted Answer · 2019-03-01 11:55:19Z

4

You can use the --slurp option to read both files into one array, and from there it's relatively simple to loop over the keys of one of the arrays and add the corresponding elements of both arrays together.

jq --slurp ' { combined: [ .[0].input as $is| .[1].result as $rs| range(0; $is|length) as $n| $is[$n]+$rs[$n] ] } ' file1.json file2.json

edited Mar 1, 2019 at 11:55

answered Feb 28, 2019 at 14:54

Michał Politowski

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4 Comments

peak Over a year ago

This approach nicely avoids reduce but using keys introduces an unnecessary inefficiency. It would be far better to use range(0; $is|length) to effect the iteration.

Michał Politowski Over a year ago

@peak That seems to be right (for values of "far better" equal to about 5% performance gain and about 1% memory saved on 1M entries). Changing the code.

peak Over a year ago

@MichałPolitowski - By "far better" I had in mind the role that SO plays in illustrating best practices.

Michał Politowski Over a year ago

@peak, well, best practices include measuring the impact of a change, don't they? :)

Jeff Mercado · Accepted Answer · 2019-02-28 20:19:10Z

If more recent versions of jq were available to you, you could take advantage of the transpose function to combine them rather easily:

$ jq -n '{ combined: ([inputs[]] | transpose | map(add)) }' input1.json input2.json

However, since you are limited to 1.4, your options are bit limited. When working with multiple files, it's useful to have all the inputs read into memory. --slurp allows you to do this reading all inputs in as an array. You will have to zip the inputs together differently however.

$ jq --slurp 'add | reduce range(0; .input | length) as $i (.; .combined += [.input[$i] + .result[$i]] ) | {combined}' input1.json input2.json

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