CODEWITHSUNDEEP
jsonbashjq
Adi
Adi

Reputation: 51

Optional key in JQ

Input content (somejson.json) is

{ "m1": "1 some m1", "m2": null , "m3" : "unwanted"}
{ "m1": "2 some m1", "m3" : "unwanted"}
{ "m1": "3 some m1", "m2": "3 some m2" , "m3" : "unwanted"}
{ "m1": "4 some m1", "m3" : "unwanted"}

Is there an option to extract, say m1. Also extract m2 if exists ?

Example. For m1 I use the the below command

cat somejson.json |jq '.m1'

Output

"1 some m1"
"2 some m1"
"3 some m1"
"4 some m1"

For m2 I use the the below command

cat somejson.json |jq '.m2'

Output

null
null
"3 some m2"
null

But I want a merged results including both m1 and m2 like below

"1 some m1"
"2 some m1"
"3 some m1"
"3 some m2"
"4 some m1"

Upvotes: 4

Views: 3075

Answers (2)

mickp
mickp

Reputation: 1809

To always extract m1:

jq '.m1, if (.m2 != null) then .m2 else empty end' somejson.json

Upvotes: 2

Amadan
Amadan

Reputation: 198324

Get both values; they will be null if they don't exist. Then just filter the nulls from the result.

<somejson.json jq '.m1, .m2 | select(. != null)'

Upvotes: 5

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