create an object from an existing json file using 'jq' - json

Question

I have a messages.json file
[
{
"id": "title",
"description": "This is the Title",
"defaultMessage": "title",
"filepath": "src/title.js"
},
{
"id": "title1",
"description": "This is the Title1",
"defaultMessage": "title1",
"filepath": "src/title1.js"
},
{
"id": "title2",
"description": "This is the Title2",
"defaultMessage": "title2",
"filepath": "src/title2.js"
},
{
"id": "title2",
"description": "This is the Title2",
"defaultMessage": "title2",
"filepath": "src/title2.js"
},
]
I want to create an object
{
"title": "Dummy1",
"title1": "Dummy2",
"title2": "Dummy3",
"title3": "Dummy4"
}
from the top one.
So far I have
jq '.[] | .id' src/messages.json;
And it does give me the IDs
How do I add some random text and make the new object as above?
Can we also create a new JSON file and write the newly created object onto it using jq?

Answer 1

Your output included "title3" so I'll assume that you intended that the second occurrence of "title2" in the input was supposed to refer to "title3".
With this assumption, the following jq program seems to do what you want:
map( .id )
| . as $in
| reduce range(0;length) as $i ({};
. + {($in[$i]): "dummy\(1+$i)"})
In words, extract the values of .id, and then turn each into an object of the form: {(.id) : "dummy\(1+$i)"}
This uses string interpolation, and produces:
{
"title": "dummy1",
"title1": "dummy2",
"title2": "dummy3",
"title3": "dummy4"
}
reduce-free solution
map(.id )
| [., [range(0;length)]]
| transpose
| map( {(.[0]): "dummy\(.[1]+1)"})
| add
Output
Can we also create a new json file and write the newly created object onto it using jq?
Yes, just use output redirection:
jq -f program.jq messages.json > output.json
Addendum
I want a parent object "de" to the already created json file objects
You could just pipe either of the above solutions to: {de: .}