How to conditionally add key to json if it doesn't exist? - json

Question

I have a json file with the following data:
{
"Index" : {
"example_user" : {
"important_key" : "leave_me_alone",
"blah" : {
"more_stuff" : {
"ignore_this" : "and_this_too"
}
}
},
"another_user" : {
"blah" : {
"more_stuff" : {
"ignore_this" : "and_this_too"
}
}
},
"extra_person" : {
"blah" : {
"more_stuff" : {
"ignore_this" : "and_this_too"
}
}
}
}
}
As you can see, important_key is missing from another_user and extra_person.
My goal is to conditionally add "imporant_key" : "" where it is missing but not replace any existing important_key values. The program i use is JQ (1.6) from https://stedolan.github.io/jq/.
After many failed attempts on jqplay.org and having intensively (re)searched the internet on how to get the job done , i've only managed to realize the following:
Filter:.Index[]+={"important_key":"data"}
Result
{
"Index": {
"example_user": {
"important_key": "data",
"blah": {
"more_stuff": {
"ignore_this": "and_this_too"
}
}
},
"another_user": {
"blah": {
"more_stuff": {
"ignore_this": "and_this_too"
}
},
"important_key": "data"
},
"extra_person": {
"blah": {
"more_stuff": {
"ignore_this": "and_this_too"
}
},
"important_key": "data"
}
}
}
I'm aware += (over)writes any existing key value (note example_user). I've been experimenting with multiple piped filters/operators, including |= and { }, but in the end, the above result was the closest i could get.
(unfortunately i can't seem to find the jqplay code snippet where i went "crazy" with everything)

Answer 1

The moment you have to conditionally do something, you have to do some sort of filtering, either using if or select or other means.
For every object you wish to inspect, check if the object has your important_key and add it when necessary. If it has the key, do nothing, otherwise set it.
.Index[] |= if has("important_key") then . else .important_key = $myImportantKey end