Hey all, I am getting a "doubled" promises in some of my code and I end up manually casting. Is ther...

# javascript

[bsimmons]

Hey all, I am getting a "doubled" promises in some of my code and I end up manually casting. Is there a way to avoid this anti-pattern?

/** Convert promise with HTTP 500 response to failed promise. */
fun Promise<Response>.handleErrorCodes(): Promise<Response> = then { response ->
    if(response.ok) response
    else response.text().then { body ->
        throw RuntimeException("${response.status}: $body")
    }
}.then { it as Response }

[thana]

JS would cast a a Promise<Promise<T>> automatically into Promise<T> . As Kotlin cannot do this, there is a extension function unwrapping it for you.
but still you'd have to write then {it}

[thana]

yet, under the hood it still makes a type cast, but at least you dont see it 😄

[turansky]

https://youtrack.jetbrains.com/issue/KT-19672

[bsimmons]

Fair enough, I guess I'll just have to keep casting.