How to merge 2 JSON objects from 2 files using jq?

I'm using the jq tools (jq-json-processor) in shell script to parse json.

I've got 2 json files and want to merge them into one unique file

Here the content of files:

file1

{
    "value1": 200,
    "timestamp": 1382461861,
    "value": {
        "aaa": {
            "value1": "v1",
            "value2": "v2"
        },
        "bbb": {
            "value1": "v1",
            "value2": "v2"
        },
        "ccc": {
            "value1": "v1",
            "value2": "v2"
        }
    }
}

file2

{
    "status": 200,
    "timestamp": 1382461861,
    "value": {
        "aaa": {
            "value3": "v3",
            "value4": 4
        },
        "bbb": {
            "value3": "v3"
        },      
        "ddd": {
            "value3": "v3",
            "value4": 4
        }
    }
}

expected result

{
    "value": {
        "aaa": {
            "value1": "v1",
            "value2": "v2",
            "value3": "v3",
            "value4": 4
        },
        "bbb": {
            "value1": "v1",
            "value2": "v2",
            "value3": "v3"
        },
        "ccc": {
            "value1": "v1",
            "value2": "v2"
        },
        "ddd": {
            "value3": "v3",
            "value4": 4
        }
    }
}

I try a lot of combinations but the only result i get is the following, which is not the expected result:

{
  "ccc": {
    "value2": "v2",
    "value1": "v1"
  },
  "bbb": {
    "value2": "v2",
    "value1": "v1"
  },
  "aaa": {
    "value2": "v2",
    "value1": "v1"
  }
}
{
  "ddd": {
    "value4": 4,
    "value3": "v3"
  },
  "bbb": {
    "value3": "v3"
  },
  "aaa": {
    "value4": 4,
    "value3": "v3"
  }
}

Using this command:

jq -s '.[].value' file1 file2

Solution 1:

Since 1.4 this is now possible with the * operator. When given two objects, it will merge them recursively. For example,

jq -s '.[0] * .[1]' file1 file2

Important: Note the -s (--slurp) flag, which puts files in the same array.

Would get you:

{
  "value1": 200,
  "timestamp": 1382461861,
  "value": {
    "aaa": {
      "value1": "v1",
      "value2": "v2",
      "value3": "v3",
      "value4": 4
    },
    "bbb": {
      "value1": "v1",
      "value2": "v2",
      "value3": "v3"
    },
    "ccc": {
      "value1": "v1",
      "value2": "v2"
    },
    "ddd": {
      "value3": "v3",
      "value4": 4
    }
  },
  "status": 200
}

If you also want to get rid of the other keys (like your expected result), one way to do it is this:

jq -s '.[0] * .[1] | {value: .value}' file1 file2

Or the presumably somewhat more efficient (because it doesn't merge any other values):

jq -s '.[0].value * .[1].value | {value: .}' file1 file2

Solution 2:

Use jq -s add:

$ echo '{"a":"foo","b":"bar"} {"c":"baz","a":0}' | jq -s add
{
  "a": 0,
  "b": "bar",
  "c": "baz"
}

This reads all JSON texts from stdin into an array (jq -s does that) then it "reduces" them.

(add is defined as def add: reduce .[] as $x (null; . + $x);, which iterates over the input array's/object's values and adds them. Object addition == merge.)

Solution 3:

Who knows if you still need it, but here is the solution.

Once you get to the --slurp option, it's easy!

--slurp/-s:
    Instead of running the filter for each JSON object in the input,
    read the entire input stream into a large array and run the filter just once.

Then the + operator will do what you want:

jq -s '.[0] + .[1]' config.json config-user.json

(Note: if you want to merge inner objects instead of just overwriting the left file ones with the right file ones, you will need to do it manually)

Solution 4:

Here's a version that works recursively (using *) on an arbitrary number of objects:

echo '{"A": {"a": 1}}' '{"A": {"b": 2}}' '{"B": 3}' |\
  jq --slurp 'reduce .[] as $item ({}; . * $item)'

{
  "A": {
    "a": 1,
    "b": 2
  },
  "B": 3
}