CODEWITHSUNDEEP
jsonbashjq
MaryCoding
MaryCoding

Reputation: 664

Jq handling empty strings and replacing them with a default value

I currently have a json file I am manipulating with jq. I am able to display it how I want for the most part. However, I am running into a problem when displaying values for a field that's empty. I am using the // alternative operator but it is not returning the desired output. What is the right way to handle empty strings with jq?

Current Output:

RELEASE    INSTALLED  LATEST  DEPRECATED
test-app   1.0.0      2.0.0   false
test-app2  3.0.0      true

Desired Output:

RELEASE    INSTALLED  LATEST  DEPRECATED
test-app   1.0.0      2.0.0   false
test-app2  3.0.0      -        true

Jq:

cat test1.json | jq -r 'map({release, installed: .Installed.version, latest: (.Latest.version // "-"), deprecated}) | ( .[0] | keys_unsorted | map(ascii_upcase)), (.[] | [.[]]) | @tsv' | column -t

Json:

[
  {
    "release": "test-app",
    "Installed": {
      "version": "1.0.0",
      "appVersion": ""
    },
    "Latest": {
      "version": "2.0.0",
      "appVersion": ""
    },
    "outdated": true,
    "deprecated": false
  },
  {
    "release": "test-app2",
    "Installed": {
      "version": "3.0.0",
      "appVersion": ""
    },
    "Latest": {
      "version": "",
      "appVersion": ""
    },
    "outdated": false,
    "deprecated": true
  }
]

Upvotes: 4

Views: 9499

Answers (2)

Jeff Mercado
Jeff Mercado

Reputation: 134871

If empty string "" is the only case you want to treat as null, you could just use the alternative operator to force to it then replace as needed.

.Latest.version // "" | select(. != "") // "-"

# or using if-then-else
.Latest.version // "" | if . == "" then "-" else . end

# or if you're using the latest dev version, else is optional
.Latest.version // "" | if . == "" then "-" end

Upvotes: 9

644
644

Reputation: 639

"" is not classed as null as Philippe pointed out, but if you're unable to change the json to make the "" become null, what you can do is

jq -r 'map({release, installed: .Installed.version, latest: (if .Latest.version == "" then "-" else .Latest.version end), deprecated}) | ( .[0] | keys_unsorted | map(ascii_upcase)), (.[] | [.[]]) | @tsv' data.json | column -t

Upvotes: 2

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