Already the second time (now in unit tests) that i...

# arrow

[dave08]

Already the second time (now in unit tests) that it would be nice to have something in the Kotlinx serialization optics library a way to get a lens to a List<String> on the `name`s here:

[{ "id":1, "name": "this"}, {"id":2, "name": "that"}]

[Sam]

If only this was Groovy, you could just write list.name 🧌

[simon.vergauwen]

JsonPath.every.select("name") works for this, no?

[simon.vergauwen]

JsonPath.every.select("name").getOrNull(jsonElement)

[dave08]

Nope, that gives a List<JsonElement>

[simon.vergauwen]

JsonPath.every.select("name").string.getOrNull(jsonElement)

[Alejandro Serrano Mena]

you always need something like string to ensure that you’re targeting the right type of element

[dave08]

👍🏼 It seems like that does it, but there's no getOrNull there, just getAll...?

[dave08]

This is all a bit confusing about Optics... I'm still not sure what returns what and when...

[Alejandro Serrano Mena]

I think it should be getAll in this case, since you want to return a list of elements

[dave08]

image.png

[Alejandro Serrano Mena]

• `getAll`returns List<T>, available for Every, Optional, Prism, Lens
• getOrNone returns Option<T>, available for Optional, Prism, Lens
• `get`` returns T, available for Lens

[Alejandro Serrano Mena]

PEvery<JsonElement, JsonElement, String, String is equivalent to Every<JsonElement, String>

[dave08]

So I'm using Every here? Why do PTraversal and PSetter appear there and when would I use them?

[dave08]

For setting that list "in place"?

[Alejandro Serrano Mena]

sorry, my bad, I meant to mention Every in the list above

[Alejandro Serrano Mena]

the reason why you get the others is because optics form a hierarchy

[Alejandro Serrano Mena]

a Every is a Traversal, which is both a Fold (which is the base interface containing getAll) and a Setter (which is the base interface containing modify)