Merge Arrays of JSON

Solution 1:

You can merge your files with add (jq 1.3+):

jq -s '.[0].list=[.[].list|add]|.[0]' *.json

or flatten (jq 1.5+):

jq -s '.[0].list=([.[].list]|flatten)|.[0]' *.json

[.[].list] - creates an array of all "list" arrays

 [
  [
    {
      "name": "Ajay"
    }
  ],
  [
    {
      "name": "Al"
    }
  ]
]

[.[].list]|flatten - flatten it (or .[].list|add - add all the arrays together)

[
  {
    "name": "Ajay"
  },
  {
    "name": "Al"
  }
]

.[0].list=([.[].list]|flatten)|.[0] - replace the first "list" with the merged one, output it.

{
  "title": "NamesBook",
  "list": [
    {
      "name": "Ajay"
    },
    {
      "name": "Al"
    }
  ]
}

Solution 2:

Let me also provide just what the title asks for, because I'm sure a lot of people that stepped on this question look for something simpler.

Any of the following (added math2001 and pmf answers):

echo -e '["a","b"]\n["c","d"]' | jq -s 'add'

echo -e '["a","b"]\n["c","d"]' | jq -s 'flatten(1)'

echo -e '["a","b"]\n["c","d"]' | jq -s 'map(.[])'

echo -e '["a","b"]\n["c","d"]' | jq -s '[.[][]]'

echo -e '["a","b"]\n["c","d"]' | jq '.[]' | jq -s

results in:

[
"a",
"b",
"c",
"d"
]

Note: Also any of the above can apply to arrays of objects.