CODEWITHSUNDEEP
jsonvariablespathjq
DPS
DPS

Reputation: 13

JQ: Using variable for dot notation path

Is it possible to use a variable to hold a dot notation path? (I'm probably not using the correct term.)

For example, given the following json:

{
  "people": [
    {
      "names": {
        "given": "Alice",
        "family": "Smith"
      },
      "id": 47
    },
    {
      "id": 42
    }
  ]
}

Is it possible to construct something like:

.names.given as $ng | .people[] | select(.id==47) | ($ng)

and output "Alice"?

The idea is to allow easier modification of a complex expression. I've tried various parens and quotes with increasing literal results ('.names.given' and '$ng')

Upvotes: 1

Views: 1163

Answers (2)

peak
peak

Reputation: 116780

The answer is no and yes: as you've seen, once you write an expression such as .names.given as $ng, $ng holds the JSON values, not the path.

But jq does support path expressions in the form of arrays of strings and/or non-negative integers. These can be used to access values in conjunction with the built-in getpath/1.

So you could, for example, write something along the lines of:

["names", "given"] as $ng
| .people[]
| select(.id==47)
| getpath($ng)

Converting jq paths to JSON arrays

It's possible to convert a "dot notation" path into an "array path" using path/1; e.g. the assignment to $ng above could be written as:

(null | path(.names.given)) as $ng

Upvotes: 2

devang
devang

Reputation: 5516

Your question and the example you provided seems very confusing to me. The jist that I got is that you want to assign a name to a value obtained from dot notation and then use it at a later point in time.

See if this is of any help -

.people | map(select(.id = 47))[0].names.given as $ng | $ng

Upvotes: -1

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