Async response validation #106
Description
If we need to read a content on validation like this
let validateResponse (content:HttpContent) = task {
let! result = content.ReadAsStringAsync()
let! stream = content.ReadAsStreamAsync()
stream.Seek(0L, SeekOrigin.Begin) |>ignore
return not <| result.StartsWith("<!DOCTYPE html>")
}then validator must be asynchronous like this
let validateAsync<'TContext, 'TSource>
(predicate: 'TSource -> Task<bool>)
(source: Pipeline<'TContext, 'TSource>)
: Pipeline<'TContext, 'TSource> =
fun next ->
{ new IAsyncNext<'TContext, 'TSource> with
member _.OnSuccessAsync(ctx, value) =
task{
let! isValid = predicate value
if isValid then return! next.OnSuccessAsync(ctx, value)
else return! next.OnErrorAsync(ctx, SkipException "Validation failed")
}
member _.OnErrorAsync(ctx, exn) = next.OnErrorAsync(ctx, exn)
member _.OnCancelAsync(ctx) = next.OnCancelAsync(ctx) }
|> source