F＃处理CSV，按记录解析记录

Question

I'm new to F# basically i'm attempting to use the FileHelpers library to import the csv record by record. So i can then place each object in a queue.

let importOrders (filePath:string) = do
       let engine = new FileHelpers.FileHelperAsyncEngine(typeof<DataTypes.Order.OrderType>)
       engine.BeginReadFile(filePath)
       for o in engine do
         unProccessedData.Enqueue(o)

However its saying that engine is not a type who's value can be enumerated yet it implements IEnumerable. Anyone got any suggestions on a possible fix or a different approach.

I need to be able to process the csv record by record, converting each into the orderType and then storing the order onto the queue. Thanks for the help guys

Answer 1

The type of engine (which is called FileHelperAsyncEngine ) only implements the non-generic version of IEnumerable , but it does not implement generic IEnumerable<T> which is required by the F# compiler.

You'll need to cast the non-generic IEnumerable to generic IEnumerable<obj> (or to some other instantiation of the generic type, depending on what is the type of values in the collection). The following should do the trick:

let importOrders (filePath:string) = 
    let engine = new FileHelpers.FileHelperAsyncEngine(typeof<OrderType>) 
    engine.BeginReadFile(filePath) 
    for o in engine |> Seq.cast<obj> do // NOTE: Conversion using Seq.cast
        unProccessedData.Enqueue(o)