Python jmespath: How to return value inside nested dict if outer dict key matches criteria

Question

The data is

data_case_c = {
    "qualities": {
        "id": "0123456789",
        "key_criteria": "Target",
        "desired_value": {"id": "987654321", "label": "CORRECT"},
    }
}

I want check that key_criteria is Target. And if it is, return qualities.desired_value.label, which is CORRECT in this case.

Here is the query I thought might work

query = "qualities.key_criteria == 'Target' | qualities.desired_value.label"

It returns None.

The first half of the expression returns True.

query = "qualities.key_criteria == 'Target'"

How can I return the actual value of qualities.desired_value.label when a key on the same level as desired_value matches a specific criteria?

score 1 · Accepted Answer · answered Aug 28 '23 at 22:35

In order to filter, in JMESPath, you do need a JSON array, which you can achieve on an object with the to_array function

to_array(qualities)

Then you have to throw your filter projection in:

to_array(qualities)[?key_criteria == `Target`]

Select the attribute you want to query:

to_array(qualities)[?key_criteria == `Target`].desired_value.label

And finally, get rid of the array you created to be able to filter, with a pipe expression:

to_array(qualities)[?key_criteria == `Target`].desired_value.label | [0]

And with all this, on your example JSON, you end up with:

"CORRECT"

Ah, it needs to be an array. Thanks! That works – sam Aug 28 '23 at 23:09 — sam, Aug 28 '23 at 23:09

Python jmespath: How to return value inside nested dict if outer dict key matches criteria

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