json_map()

json_map()

json_map([<object>/]<attribute>, <json>[, <osep>[, <arg>[, ..., <argN>]]])

This function iterates over a JSON string, calling the specified <attribute> for each element of the JSON. If <json> represents a basic JSON type (null, boolean, string or number), the attribute will be called once. For arrays and objects, it will be called once for each element of the array/object.

When the attribute is called, %0 will be the type of the json object and %1 will be the value. When <json> is an array, %2 will be the array position of the current element. For objects, %2 will be the label of the current element. You can pass user-specified arguments to the attribute; the first <arg> will be available as %3, the second as %4, and so on.

<osep> defaults to a space.

::: seealso

• json()
• json_query() :::

Mapping primitive values

A very basic example:

&json me=We got [art(%0)] %0: %1

> think json_map(me/json, "foo")
We got a string: foo

> think json_map(me/json, \["foo"\, 5\], %r)
We got a string: foo
We got a number: 5

> think json_map(me/json, \["foo"\, \["bar"\, 10\]\], %r)
We got a string: foo
We got an array: ["bar",10]

Nested pretty printer

A JSON pretty-printer, using nested calls to json_map() to handle nested
JSON objects/arrays:

> &pretty_json me=u(me/pretty_json_sub,,%0,,0,strmatch(%0,\\{*))
> &pretty_json_sub me=repeat(%t,%3)[if(%4,json(string,%2):%b)][switch(%1,\{*,\{%r[json_map(%=,%1,\,%r,inc(%3),1)]%r[repeat(%t,%3)]\},\[*,\[%r[json_map(%=,%1,\,%r,inc(%3),0)]%r[repeat(%t,%3)]\],json(%0,%1))]

> &json me=[5, null, ["nested!", 999, {"foo":5, "bar":"\"Whee\""}], 7]
> th u(me/pretty_json, v(json)
[
  5,
  #-1,
  [
      "nested!",
      999,
      {
          "foo": 5,
          "bar": "\"Whee\""
      }
  ],
  7
]