Modifying array of key value in JSON jq - json

Question

In case, I have an original json look like the following:
{
"taskDefinition": {
"containerDefinitions": [
{
"name": "web",
"image": "my-image",
"environment": [
{
"name": "DB_HOST",
"value": "localhost"
},
{
"name": "DB_USERNAME",
"value": "user"
}
]
}
]
}
}
And I would like to inplace modify the value for the matched key like so:
jq '.taskDefinition.containerDefinitions[0].environment[] | select(.name=="DB_USERNAME") | .value="new"' json
I got the output
{
"name": "DB_USERNAME",
"value": "new"
}
But I want more like in-place modify or the whole json from the original with new value modified, like this:
{
"taskDefinition": {
"containerDefinitions": [
{
"name": "web",
"image": "my-image",
"environment": [
{
"name": "DB_HOST",
"value": "localhost"
},
{
"name": "DB_USERNAME",
"value": "new"
}
]
}
]
}
}
Is it possible to do with jq or any known workaround?
Thank you.
Updated
For anyone looking for editing multi-values,
here is the approach I use
JQ=""
for e in DB_HOST=rds DB_USERNAME=xxx; do
k=${e%=*}
v=${e##*=}
JQ+="(.taskDefinition.containerDefinitions[0].environment[] | select(.name==\"$k\") | .value) |= \"$v\" | "
done
jq '${JQ%??}' json
I think there should be more concise way, but this seems working fine.

Answer 1

It is enough to assign to the path, if you are using |=, e.g.
jq '
(.taskDefinition.containerDefinitions[0].environment[] |
select(.name=="DB_USERNAME") | .value) |= "new"
' infile.json
Output:
{
"taskDefinition": {
"containerDefinitions": [
{
"name": "web",
"image": "my-image",
"environment": [
{
"name": "DB_HOST",
"value": "localhost"
},
{
"name": "DB_USERNAME",
"value": "new"
}
]
}
]
}
}

Answer 2

Here is a select-free solution using |=:
.taskDefinition.containerDefinitions[0].environment |=
map(if .name=="DB_USERNAME" then .value = "new"
else . end)
Avoiding select within the expression on the LHS of |= makes the solution more robust w.r.t. the version of jq being used.

Answer 3

You might like to consider this alternative to using |=:
walk( if type=="object" and .name=="DB_USERNAME"
then .value="new" else . end)