Question

I need to find a certain hash element where one of the keys is equal to a certain value. I’ve tried many ways and can’t seem to figure it out with jsonpath gem.

Need to get tire tag where grip == 'bad'

require "jsonpath"

hash = {
    :id => 1,
    :cars => [
        {:id => 1, :tire => {:grip => "good", :color => "black"}},
        {:id => 2, :tire => {:grip => "bad", :color => "red"}},
        {:id => 3, :tire => {:grip => "good", :color => "green"}}
    ]
}

puts JsonPath.on(hash, "$..tire[?(@['grip'] == 'bad')]").inspect

No results.

Answer 1

The [?()] filter only works for arrays (or at least for either arrays or hashes, not both at the same time). In order for it to work, I had to enclose the :tire hash in an array.

Original:

:tire => {:grip => "good", :color => "black"}

New:

:tire => [{:grip => "good", :color => "black"}]

That’s a “fix” that works for me. It would be better if someone fixed the jsonpath gem to make it work for both arrays and hashes (of the same type and at the same time).