How to Add a Key-Value Pair to a JSON File with JQ

jqjson

I have the following JSON file located at /tmp/target.json:

{
  "compileOnSave": false,
  "compilerOptions": {
    "baseUrl": "./",
    ...
  }
}

I want to add a new key value pair so it will be as follows:

{
  "compileOnSave": false,
  "compilerOptions": {
    "skipLibCheck": true,
    "baseUrl": "./",
    ...
  }
}

I use the following command but it doesn't work:

jq --argjson addobj '{"skipLibCheck": "true"}' '
  .compilerOptions{} |= $addobj
' /tmp/target.json

I gives me this error:

jq: error: syntax error, unexpected '{', expecting $end (Unix shell quoting issues?) at <top-level>, line 2:
  .compilerOptions{} |= $addobj                  
jq: 1 compile error

What have I done wrong? How can I get it to work as intended?

Best Answer

Like this:

$ jq '.compilerOptions.skipLibCheck=true' file.json
{
  "compileOnSave": false,
  "compilerOptions": {
    "baseUrl": "./",
    "skipLibCheck": true
  }
}

Related Solutions

JSON – How to Extract and Print Key-Value Pairs Matching a Pattern

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
)[]

json – Get Key and Value from JSON in Array with Check

You can use to_entries, then select the non-null keys and extract the values:

jq 'to_entries | map(select(.key != "null"))[] | (.key, .value.type)' < file2.json

Best Answer

Related Solutions

JSON – How to Extract and Print Key-Value Pairs Matching a Pattern

json – Get Key and Value from JSON in Array with Check

Related Question