Using JMESPath, filter array elements based on length of an array-valued property

Question

Given an input like this:

[
  {
    "a": "foo",
    "b": [ 1, 2, 3 ]
  },
  {
    "a": "bar",
    "b": [ ]
  },
  {
    "a": "baz",
    "b": [ 2 ]
  }
]

I want to filter out the elements that have a zero-length array for their b property to give:

[
  {
    "a": "foo",
    "b": [ 1, 2, 3 ]
  },
  {
    "a": "baz",
    "b": [ 2 ]
  }
]

How do I do this with JMESPath?

score 3 · Answer 1 · edited Jan 26 '22 at 09:45

3

You can use

[?length(b)>'0']

edited Jan 26 '22 at 09:45

answered Jan 12 '22 at 16:26

Dominik Brázdil

1

That certainly looks more intuitive! – James World Jan 12 '22 at 16:28
`[?length(b) > 0]`, even. No need to create possible side effects by comparing a number [`number length(string|array|object $subject) `](https://jmespath.org/specification.html#length) to a litteral. – β.εηοιτ.βε Jan 26 '22 at 09:48
Using number caused some errors for me when using JMESPath in JSON beautifier Chrome extension. But certainly if it works it is preffered. – Dominik Brázdil Jan 27 '22 at 10:08

score 1 · Answer 2 · answered Sep 19 '19 at 13:18

1

I figured this out, simple in the end although the function name is a little misleading. All you need is this:

[?not_null(b)]

answered Sep 19 '19 at 13:18

James World

score 0 · Answer 3 · answered Nov 09 '22 at 00:27

Extendind @Dominik Brázdil answer, was able to achieve following in aws cli command.

Note : Double quotes " did not work, use single quotes '

aws apigateway get-usage-plans --query 'items[?length(apiStages[])>`0`].id' --max-items 5 --profile TPaaSProd

If you want to query json items whose specific particular value is empty or length is zero (0).

aws apigateway get-usage-plans --query 'items[?length(apiStages[])==`0`].id' --max-items 5 --profile TPaaSProd

3 Answers3