How to get the length of a JSON array using JSONPath?

Question

If I have JSON document like this

[
    {
        "number" : "650-462-9154",
        "type" : "main"
    },
    {
        "number" : "650-462-1252",
        "type" : "fax"
    }
]

What JSONPath can I use to get the array length (which is 2), without hardcoding any property values?

Using the tool I have, here is some examples they gave, which doesn't help me figure out what value I need.

[
  { 
    "type": "add",
    "id":   "tt0484562",
    "version": 1,
    "lang": "en",
    "fields": {
      "title": "The Seeker: The Dark Is Rising",
      "director": "Cunningham, David L.",
      "genre": ["Adventure","Drama","Fantasy","Thriller"],
      "actor": ["McShane, Ian","Eccleston, Christopher","Conroy, Frances",
                "Crewson, Wendy","Ludwig, Alexander","Cosmo, James",
                "Warner, Amelia","Hickey, John Benjamin","Piddock, Jim",
                "Lockhart, Emma"]
    }
  },
  { 
    "type": "delete",
    "id":   "tt0484575",
    "link_ref": null,
    "version": 2
  }
]

$.[0].genre ---> 0
$.[0].fields.genre ---> 1
$.[0].fields.genre[*] ---> 4
$.[*].type ---> 2
$.[1].link_ref ---> 1

What is the definition of GetJSONValueCount?

Heretic Monkey
– Heretic Monkey

2018-08-20 15:49:00 +00:00
Commented Aug 20, 2018 at 15:49 — Heretic Monkey
– Heretic Monkey, Commented Aug 20, 2018 at 15:49
Added too much info, made it cleaner now.

omega
– omega

2018-08-20 15:51:49 +00:00
Commented Aug 20, 2018 at 15:51 — omega
– omega, Commented Aug 20, 2018 at 15:51
The program I use, accepts it in that format.

omega
– omega

2018-08-20 15:52:03 +00:00
Commented Aug 20, 2018 at 15:52 — omega
– omega, Commented Aug 20, 2018 at 15:52

Viktor · Accepted Answer · 2020-05-17 09:32:18Z

3

You can get the length of the array from the first example by using the .length() function like this :

$.length

That should return something like this:

[
    2
]

As for the second example, you can access any array keys using regular dot notation ($.node1.node2.node3) and call the length() function on the node key you wish to get the length of. For example, if you wanted to get the number of values in the actor array you could do something like:

$..actor.length

Which will return something like this:

[
    10
]

Tested on https://codebeautify.org/jsonpath-tester and http://jsonpath.com/ .

You can find more functions in the jsonpath github repo.

edited May 17, 2020 at 9:32

answered Sep 7, 2018 at 10:42

Viktor

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2 Comments

Evren Yurtesen Over a year ago

where are the valid jsonpath functions are documented?

Benas Apr 11 at 12:52

"$.length()" solved the issue

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