Non destructive assignation with jq - json

Question

I got the following data:
{
"things": [
{
"name": "lkj",
"something": [
"hike"
],
"more_data": "important",
"other_stuff": "very important"
},
{
"name": "iou",
"different_more_data": "very important too",
"more_different_data": [
"even more"
]
}
]
}
Each of things has an id called "name", with jq I can edit it like:
jq '(.things[]) |= {name,something:["changed"]}'
{
"things": [
{
"name": "lkj",
"something": [
"changed"
]
},
...
Unfortunately I lose everything not declared in the right hand of the assignation operation.
Is there a way to make assignations without losing data? So that the result is like this:
{
"things": [
{
"name": "lkj",
"something": [
"changed"
],
"more_data": "important",
"other_stuff": "very important"
},
{
"name": "iou",
"something": [
"changed"
],
"different_more_data": "very important too",
"more_different_data": [
"even more"
]
}
]
}

Answer 1

You can simply modify your query so that it looks like:
.things[] |= (.something = ["changed"])
You can also use |= (or one of its siblings, such as +=) instead of = in the RHS expression, e.g.
.things[] |= (.something += ["changed"])
If you want to update some, but not all, items, you can still use the above forms. A straightforward approach is to use if ... then ... else ... end, for example:
.things[] |= (if .name == "lkj" then .something = ["changed"] else . end)
Using select on the LHS of |=
jq (or at least jq since version 1.4) does support the use of select on the LHS of |=, e.g.
(.things[] | select(.name=="lkj")) |= (.something += ["changed"])

Answer 2

With jq's map function:
jq '.things |= map(.something = ["changed"])' jsonfile
map(x) - apply specified filter x for each item of the input array
.something = ["changed"] - set key something to an object with array ["changed"] as a value
The output:
{
"things": [
{
"name": "lkj",
"something": [
"changed"
],
"more_data": "important",
"other_stuff": "very important"
},
{
"name": "iou",
"different_more_data": "very important too",
"more_different_data": [
"even more"
],
"something": [
"changed"
]
}
]
}