Blog.FSharpWebAPI\Handlers.fs

let labelUpdateHandler (id : int) = 
    fun (next : HttpFunc) (ctx : HttpContext) -> 
        task { 
            let context = ctx.RequestServices.GetService(typeof<LabelsContext>) :?> LabelsContext
            let! label = ctx.BindJsonAsync<CreateUpdateLabelRequest>()
            match label.HasErrors with
            | Some msg -> return! (setStatusCode 400 >=> json msg) next ctx
            | None -> 
                return! updateLabel context label.GetLabel id |> function 
                        | Some l -> ctx.WriteJsonAsync l
                        | None -> (setStatusCode 400 >=> json "Label not updated") next ctx
        }