Question 109162 in Json Question posted in
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Edit objects in json array based on strings in another array with jq

For some reason I just can’t wrap my head around jq. I’ve been going around in circles for hours trying to accomplish what I think is not too difficult a task.
With json consisting of two arrays as input, I want to search for objects in the second array whereby the name field value is an element of the first array, and then add a field, say "found": true, to those objects.

[
    [
        "test1",
        "test2",
        "test3"
    ],
    [
        {
            "name": "test5",
            "data": "five"
        },
        {
            "name": "test1",
            "data": "four"
        },
        {
            "name": "test2",
            "data": "three"
        },
        {
            "name": "test3",
            "data": "six"
        }
    ]
]

My best guess so far starts with…
.[0] as $tn | (.[1] | .[] | .name | in($tn[]))
but that is not getting me close to where i want to go.

Tags:

2

Answers


  1. 0

    Your attempt has only two issues: First, you need select to filter out certain items. Second, there are two (confusingly named) functions: The one called in tests for the existence of keys in objects, the other one called IN searches for occurrence in a stream or array. You need the latter.

    .[0] as $tn | .[1][] | select(.name | IN($tn[])) | .found = true

    {
  "name": "test1",
  "data": "four",
  "found": true
}
{
  "name": "test2",
  "data": "three",
  "found": true
}
{
  "name": "test3",
  "data": "six",
  "found": true
}

    Demo

    If, however, you wanted to retain the original structure, you need to retain the top-level context until the end of your filter, while manipulating parts of it using updates |= as in:

    .[0] as $tn | (.[1][] | select(.name | IN($tn[]))).found = true

    [
  [
    "test1",
    "test2",
    "test3"
  ],
  [
    {
      "name": "test5",
      "data": "five"
    },
    {
      "name": "test1",
      "data": "four",
      "found": true
    },
    {
      "name": "test2",
      "data": "three",
      "found": true
    },
    {
      "name": "test3",
      "data": "six",
      "found": true
    }
  ]
]

    Demo

    And to set the boolean flag on all items, just assign, don’t select:

    .[0] as $tn | .[1][] |= (.found = (.name | IN($tn[])))

    [
  [
    "test1",
    "test2",
    "test3"
  ],
  [
    {
      "name": "test5",
      "data": "five",
      "found": false
    },
    {
      "name": "test1",
      "data": "four",
      "found": true
    },
    {
      "name": "test2",
      "data": "three",
      "found": true
    },
    {
      "name": "test3",
      "data": "six",
      "found": true
    }
  ]
]

    Demo

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  2. 0

    Close enough. Use IN to check for items in a stream and then assign the new property:

    first as $names
| .[1][] | select(.name|IN($names[]))
| .found = true

    Output:

    {
  "name": "test1",
  "data": "four",
  "found": true
}
{
  "name": "test2",
  "data": "three",
  "found": true
}
{
  "name": "test3",
  "data": "six",
  "found": true
}

    If you want to keep the input structure and only add found to the matching elements in the nested array, use parentheses:

    first as $names
| (.[1][] | select(.name|IN($names[]))).found = true

    Output:

    [
  [
    "test1",
    "test2",
    "test3"
  ],
  [
    {
      "name": "test5",
      "data": "five"
    },
    {
      "name": "test1",
      "data": "four",
      "found": true
    },
    {
      "name": "test2",
      "data": "three",
      "found": true
    },
    {
      "name": "test3",
      "data": "six",
      "found": true
    }
  ]
]

    And finally to transform and extract only the second array (as array):

    first as $names
| (.[1] | map(select(.name|IN($names[])).found = true))

    Output:

    [
  {
    "name": "test5",
    "data": "five"
  },
  {
    "name": "test1",
    "data": "four",
    "found": true
  },
  {
    "name": "test2",
    "data": "three",
    "found": true
  },
  {
    "name": "test3",
    "data": "six",
    "found": true
  }
]

    To keep only the matching elements (note the | before assignment of .found):

    first as $names
| (.[1] | map(select(.name|IN($names[])) | .found = true))
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