elm-concurrent-task
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andrewMacmurray
Support decoding the whole bytes response without knowing its size
Currently in version 1.1.1, the expectBytes function has the following signature:
expectBytes : Decoder a -> Expect a
Since the Elm bytes library has no decoder to get the whole bytes as Bytes without providing a byte length, it is impossible to just retrieve the whole bytes response.
In the regular elm/http library, the expectBytes function has the same issue, but we can circumvent that issue by using instead the expectBytesResponse function.
expectBytesResponse :
(Result x a -> msg)
-> (Response Bytes -> Result x a)
-> Expect msg
It seems to me that elm-concurrent-task doesn’t have such alternative, which is a blocker for me. What’s your view on adding something that enables us to get the whole bytes response instead and deal with it on our own.
Hi @mpizenberg - I'm afraid I don't really have the capacity to tackle this at the moment, but if you'd like to experiment it's possible to write your own http module + adapter (have a look at the docs here https://package.elm-lang.org/packages/andrewMacmurray/elm-concurrent-task/latest/ConcurrentTask-Http)
@mpizenberg did you ever get a chance to look at this? Re-looking at it now would something like this help?
expectMetadata : (Metadata -> Expect a) -> Expect a
So you could do something like:
expectBytesWithLength : Expect Bytes
expectBytesWithLength =
expectMetadata
(\meta ->
meta.headers
|> Dict.get "content-length"
|> Maybe.andThen String.toInt
|> Maybe.withDefault 0
|> Bytes.Decode.bytes
|> expectBytes
)
I was somewhat lucky that I didn’t really have a need for ConcurrentTask for my requests needing to read the full bytes response, so I just used the regular http requests for these, and used concurrent tasks for my other requests.
I’m not super familiar with http headers, but what you are showing makes sense.
In your case how would you determine the size of the bytes response in regular elm/http?
expectBytesResponse :
(Result x a -> msg)
-> (Response Bytes -> Result x a)
-> Expect msg
The Metadata type is the same as the type in elm/http https://package.elm-lang.org/packages/elm/http/latest/Http#Metadata
In your case how would you determine the size of the bytes response in regular elm/http?
Well I don’t need to determine the size of the bytes response because I need the whole bytes. But if I needed, I’d call the Bytes.width : Bytes -> Int function: https://elm.dmy.fr/packages/elm/bytes/latest/Bytes?q=wid#width
I see, so you're just taking the raw value from Response Bytes. In that case using Metadata wouldn't really work.
Yes indeed I need the raw bytes for something I cannot deal with directly in Elm (cannot decode it, and don’t know the size in advance)
What about this? https://github.com/andrewMacmurray/elm-concurrent-task/commit/8b1e13c0ec35a67482423570694ed5302c3453d0