Question 257838 in Json Question posted in
Our archive of expertly curated questions and answers provides insights and solutions to common problems related to this popular data interchange format. From parsing and manipulating JSON data to integrating it with various programming languages and web services, our archive has got you covered. Start exploring today and take your JSON skills to the next level

Json – Process multiple files in jq

Imagine I have two files as below:

file1:

[   
  "id1",
  "id2"
]

file2:

[
  {
    "id": "id1",
    "name": "name1"
  },
  {
    "id": "id1",
    "name": "name2"
  },
  {
    "id": "id3",
    "name": "name3"
  },
  {
    "id": "id5",
    "name": "name5"
  },
  {
    "id": "id2",
    "name": "name6"
  }
]

I want to find those entries in file2 that their id exist in file1, in the example above the expected output should be like:

[
  {
    "id": "id1",
    "name": "name1"
  },
  {
    "id": "id1",
    "name": "name2"
  },
  {
    "id": "id2",
    "name": "name6"
  }
]

How can I achieve it with jq.

Tags:

2

Answers


  1. 0

    You’ll get better/more succinct answers, but this seems to work. Slurp both files into an array, use file1.json contents as a filter to reduce file2.json.

    jq --slurp '.[0] as $filt | reduce .[1][] as $ref ([]; if IN($ref.id; $filt[]) then . + [$ref] else . end)' file1.json file2.json

    Try it on jqplay.org.

    If the file sizes are large, this might be better since it doesn’t slurp.

    jq --null-input 'input as $filt | reduce inputs[] as $ref ([]; if IN($ref.id; $filt[]) then . + [$ref] else . end)' file1.json file2.json

    Try this on jqplay.org.

    Both output:

    [
  {
    "id": "id1",
    "name": "name1"
  },
  {
    "id": "id1",
    "name": "name2"
  },
  {
    "id": "id2",
    "name": "name6"
  }
]
    Login or Signup to reply.
  2. 0

    With both inputs already being arrays, there’s no need to --slurp. Also, as there are exactly two inputs, there’s also no need to call on --null-input, just use input for the second one. For example, using the inputs in reversed order:

    jq 'input as $ids | map(select(IN(.id; $ids[])))' file2.json file1.json

    [
  {
    "id": "id1",
    "name": "name1"
  },
  {
    "id": "id1",
    "name": "name2"
  },
  {
    "id": "id2",
    "name": "name6"
  }
]

    Demo

    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search