How to Add New Key to JSON File with jq

To apply an expression to all elements of an array, and get an altered array out, use map(expression).

Extracting all entries that have off status:

$ jq 'map(select(.status == "off"))' file
[
  {
    "name": "user1",
    "status": "off"
  },
  {
    "name": "user2",
    "status": "off"
  }
]

Mapping select(.status == "off") will alter the array by extracting (selecting) only the elements for which .status == "off" is true.

Extracting only the decoded names from the above:

$ jq -r 'map(select(.status == "off"))[].name' file
user1
user2

Tucking on [].name at the end of the previous expression will first expand the array into a set of individual entries (that's what [] does) and then extract the .name value from each of those.

You could also have used

jq -r 'map(select(.status == "off").name)[]' file

... which creates an array of names from which you then extract all elements.

Setting the status to on for all entries that have an off status:

$ jq 'map(select(.status == "off").status = "on")' file
[
  {
    "name": "user1",
    "status": "on"
  },
  {
    "name": "user2",
    "status": "on"
  },
  {
    "name": "user3",
    "status": "on"
  }
]

By mapping select(.status == "off").status = "on", we modify our array by setting the status to on for any element whose status is off.

Setting the status to on for entries based on explicit names:

$ jq 'map(select(.name == "user1" or .name == "user2").status = "on")' file
[
  {
    "name": "user1",
    "status": "on"
  },
  {
    "name": "user2",
    "status": "on"
  },
  {
    "name": "user3",
    "status": "on"
  }
]

The same thing, but don't hard-code the names inside the expression. Rather, give them as a list at the end of the command line (note that --args and the list of names must be the last thing on the command line):

$ jq 'map(select(IN(.name; $ARGS.positional[])).status = "on")' file --args user1 user2
[
  {
    "name": "user1",
    "status": "on"
  },
  {
    "name": "user2",
    "status": "on"
  },
  {
    "name": "user3",
    "status": "on"
  }
]

The list of names given to --args is found in the array called $ARGS.positional.

The IN(a; b) thing returns true if a appears in the set b. We're using $ARGS.positional[] as the set to search, which is the set of the names given on the command line. This means our select() here will extract only the elements whose names occur in the list on the command line, and these will have their status set to on.

Note that IN(a; b) differs from the similarly named in(a), which returns true if a given value occurs as a key or index in the object or array a.

Setting all entries' status to on:

$ jq 'map(.status = "on")' file
[
  {
    "name": "user1",
    "status": "on"
  },
  {
    "name": "user2",
    "status": "on"
  },
  {
    "name": "user3",
    "status": "on"
  }
]

Follow-up question in comments:

And If I want to match like NOT IN(a, b), then? Clearly, I am asking if I pass value like user1 and it turns off all other than user1. How can I do so?

The following uses an explicit if statement to change the status to on for the given names and to off for all others:

jq '
    map(
        if IN(.name; $ARGS.positional[]) then
            .status = "on"
        else
            .status = "off"
        end
    )' file --args user1

Or, in a one-line layout:

jq 'map(if IN(.name; $ARGS.positional[]) then .status = "on" else .status = "off" end)' file --args user1

If I instead interpret the follow-up as not wanting to change the status of the given names, no matter what their statuses are, but to change all other statuses to off. In that case, we can negate the condition used in a previous variation:

jq 'map(select(IN(.name; $ARGS.positional[]) | not).status = "off")' file --args user1

Note the added | not after IN(...; ...).

Of course, you could have used an if statement in most of the above variations too, but I like using select() when I'm able to.

Assuming the initial " in the JSON document is a typo, that you want the .ReportName key's value from the first entry in the c array, and that you want the output as CSV:

$ jq -r '.c[0].Reportname as $n | map_values(select(type == "string" and startswith("http"))) | to_entries[] | [$n, .key, .value] | @csv' file
"XXX","a","https://is2-ssl.com/"
"XXX","b","https://a5.-ssl.com/"

The jq expression:

.c[0].Reportname as $n |
map_values(select(type == "string" and startswith("http"))) |
to_entries[] | [$n, .key, .value] | @csv

This first picks out the .Reportname value and assigns it to the internal jq variable $n. It then rewrites the original object by discarding any key not associated with a string starting with the substring http.

The example document is, after map_values() reduced to

{
  "a": "https://is2-ssl.com/",
  "b": "https://a5.-ssl.com/"
}

This is then converted with to_entries into the equivalent of

[
   { "key": "a", "value": "https://is2-ssl.com/" },
   { "key": "b", "value": "https://a5.-ssl.com/" }
]

... to get access to the keys themselves.

This array is expanded into a set of objects with [] and the saved value in $n together with the .key and .value part of each object in the set is used to create an array that is converted by @csv to quoted CSV output.

Another jq expression with the same output, but that does to_entries a bit earlier and then does map() on the created array rather than on the values of an object as we do with map_values() above.

.c[0].Reportname as $n | 
to_entries | 
map(
   select(.value | type == "string" and startswith("http")) |
   [$n, .key, .value] | @csv
)[]