Creating label from detected field whose name contains a dot

So, I’m trying to execute this expression:

{app="my_app"} | json some_value="some.value"

but it doesn’t seem to work. I tried using Go templates, like:

{app="my_app"} | label_format some_value= "{{.}}"

but it seems you can only access map of labels, and not map of detected fields.

Is there any way to work with fields which names contains dots?

For anyone interested I managed to do this:

{label="label_value"} | json field_with_dot="[\"\"]" | field_with_dot="some_value"