I'm delete all entries that do not have any dependencies, but I as I don't know jq very well, I am also having problem finding an answer.

I have:

{
  "dev": {
    "Alpha": {
      "dependencies": [
        "Gamma",
        "Delta"
      ],
      "other_value_1": [
        "aaa"
      ],
      "other_value_n": [
        "unknown number of other values"
      ]
    },
    "Beta": {
      "package_name": "some name",
      "scm": {
        "type": "git",
        "url": "git url"
      }
    },
    "Gamma": {
      "dependencies": [
        "Delta"
      ]
    },
    "Delta": {
      "dependencies": []
    }
  }
}

Out of which I want to get only the names (Alpha, Gamma) and only with dependencies inside:

{
  "dev": {
    "Alpha": {
      "dependencies": [
        "Gamma",
        "Delta"
      ]
    },
    "Gamma": {
      "dependencies": [
        "Delta"
      ]
    }
  }
}

Let's assume that there may be many unforeseen values besides dependencies

CodePudding user response：

Slightly more verbose way, without specifying the keys:

.dev |= with_entries(select(.value.dependencies | length > 0) | .value = { dependencies: .value.dependencies})

Using with_entires() to select() those where .value.dependencies has length > 0, then set (|=) value to an object only containing the dependencies

---

Will output:

{
  "dev": {
    "Alpha": {
      "dependencies": [
        "Gamma",
        "Delta"
      ]
    },
    "Gamma": {
      "dependencies": [
        "Delta"
      ]
    }
  }
}

Online demo

CodePudding user response：

Here's one way using the Object construction shortcut {name}:

jq '.dev |= ({Alpha, Gamma} | .[] |= {dependencies})'

Demo

If the keys filtered should be dynamic, selecting on has(0) can test for the existence of a first array item, i.e. for a non-empty list:

jq '.dev[] |= ({dependencies} | select(.[] | has(0)))'

Demo

Output:

{
  "dev": {
    "Alpha": {
      "dependencies": [
        "Gamma",
        "Delta"
      ]
    },
    "Gamma": {
      "dependencies": [
        "Delta"
      ]
    }
  }
}

---

CodePudding user response：

Assuming dependencies is either an array or nonexistent:

.dev |= map_values(
  select(
    .dependencies
    | IN(null, [])
    | not
  )
  | {dependencies}
)

^{Online demo}