CODEWITHSUNDEEP
jsonjq
JSB
JSB

Reputation: 360

Parse JSON field with jq and output repeatedly for every child

I have the following JSON:

    {
        "field1":"foo",
        "array":[
            {
                child_field1:"c1_1",
                child_field2:"c1_2"
            },
            {
                child_field1:"c2_1",
                child_field2:"c2_2"
            }
         ]...
    }

and using jq, I would like to return the following output, where the value of field1 is repeated for every child element.:

    foo,c1_1,c1_2
    foo,c2_1,c2_2
    ...

I can access each field separately, am having trouble returning the desired result above.

Can this be done with jq?

Upvotes: 1

Views: 205

Answers (3)

RomanPerekhrest
RomanPerekhrest

Reputation: 92854

jq solution:

jq -r '.field1 as $f1 | .array[] 
       | [$f1, .[]] 
       | join(",")' input.json

The output:

foo,c1_1,c1_2
foo,c2_1,c2_2

Upvotes: 0

peak
peak

Reputation: 116640

In cases like this, there's no need for reduce or `to_entries', or to list the fields explicitly -- one can simply exploit jq's backtracking behavior:

.field1 as $f
| .array[]
| [$f, .[]]
| @csv

As pointed out by @MatthewLDaniel, there are many alternatives to using @csv here.

Upvotes: 0

mdaniel
mdaniel

Reputation: 33158

jq -r '.array[] as $a | [.field1, $a.child_field1, $a.child_field2] | @csv'

Does the right thing for the sample data you provided, but I freely admit there are lots of ways to do that kind of thing in jq, and that was only the first one which sprang to mind.

I fed it through @csv because it seemed like that was what you wanted, but if you prefer the actual output, exactly as you have written, then:

jq -r '.array[] as $a | "\(.field1),\($a.child_field1),\($a.child_field2)"'

will produce it

Upvotes: 3

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