jq recursively update values for certain elements

问题

The intent for the JSON data below is to update the value of the field dst with the value of src within all elements of type t, regardless of depth within the tree, while at the same time preserving the whole structure of the data.

Is this possible with jq? My several attempts have boiled down to the following command that is not working to achieve the intended purpose:

$ jq -r 'map_values(select(.. | .type? == "t" |= (.dst = .src)))'

{
    "a": "b",
    "c": [
        {
            "type": "t",
            "src": "xx",
            "dst": "zz"
        },
        {
            "type": "t",
            "src": "xx",
            "dst": "zz"
        }
    ],
    "d": [
        {
            "e": [
                {
                    "type": "t",
                    "src": "xx",
                    "dst": "zz"
                }
            ]
        },
        {
            "type": "t2",
            "src": "xx",
            "dst": "zz"
        }
     ]
}

回答1:

Is this possible with jq?

jq is Turing-complete :-)

Here's a simple solution:

walk( if type == "object" and .type == "t" then .dst = .src else . end)

If your jq does not have walk/1, then it might be a good time to upgrade (to jq 1.6); otherwise, you can snarf its def from the web, e.g. by googling: jq "def walk"

Alternatively ...

reduce paths as $x (.;
    if (getpath($x)|.type? // false) == "t"
    then setpath( $x + ["dst"]; getpath( $x + ["src"] ))
    else . end)

来源：https://stackoverflow.com/questions/53145680/jq-recursively-update-values-for-certain-elements