Subqueries

[michaelko]

Suggest you have this code (from selectjson)

{
    "name": {
        "first": "Lloyd",
        "last": "Hilaiel"
    },
    "favoriteColor": "yellow",
    "languagesSpoken": [
        {
            "lang": "Bulgarian",
            "level": "advanced"
        },
        {
            "lang": "English",
            "level": "native",
            "preferred": true
        },
        {
            "lang": "Spanish",
            "level": "beginner"
        }
    ],
    "seatingPreference": [
        "window",
        "aisle"
    ],
    "drinkPreference": [
        "whiskey",
        "beer",
        "wine"
    ],
    "weight": 172
}

And you want to select all languag names you can do that with
.languagesSpoken[].lang

If you want to select only the preferred ones you can do something like
[.languagesSpoken[] | if .preferred then .lang else 0 end] but that is imo not satisfying since the list now contains a placeholder. I suggest <> a subquery syntax.

exp1<exp2> would be equivalent to [exp1[] | if exp2 then . else **Nothing** end]

languagesSpoken<.preferred>.lang would be "English"

Since it can only be applied to a array i suggest it should be languagesSpoken<.preferred> rather than ``languagesSpoken[]<.preferred>`

[stedolan]

**Nothing** is in fact implemented, and it's called empty. You can write:

[.languagesSpoken[] | if .preferred then .lang else empty end]

You can use the builtin "select" function to write it as:

[.languagesSpoken[] | select(.preferred) | .lang]

[michaelko]

Yes, please. Man, this is awesome.

[michaelko]

And a way more elegant.