it-swarm.com.de

Web-API: Wie greife ich bei Verwendung von MultipartMemoryStreamProvider auf mehrteilige Formularwerte zu?

Früher habe ich MultipartFormDataStreamProvider verwendet, um mehrteilige Anforderungen zu verarbeiten.

Da ich möchte, dass die hochgeladene Datei anstelle einer Festplattendatei im Arbeitsspeicher gespeichert wird, habe ich meinen Code so geändert, dass MultipartMemoryStreamProvider verwendet wird. Das Laden der Datei scheint in Ordnung zu sein, aber ich kann nicht mehr auf andere Formularwerte zugreifen, die über provider.FormData Unter MultipartFormDataStreamProvider verfügbar waren. Könnte mir jemand zeigen, wie das geht?

Die rohe Anfrage von Fiddler erfasst:

POST http://myserver.com/QCCSvcHost/MIME/RealtimeTrans/ HTTP/1.1
Content-Type: multipart/form-data; boundary="XbCY"
Host: na-w-lxu3
Content-Length: 1470
Expect: 100-continue
Connection: Keep-Alive

--XbCY
Content-Type: text/plain; charset=utf-8
Content-Disposition: form-data; name=PayloadType

X12_270_Request_005010X279A1
--XbCY
Content-Type: text/plain; charset=utf-8
Content-Disposition: form-data; name=ProcessingMode

RealTime
--XbCY
Content-Type: text/plain; charset=utf-8
Content-Disposition: form-data; name=PayloadID

e51d4fae-7dec-11d0-a765-00a0c91e6fa6
--XbCY
Content-Type: text/plain; charset=utf-8
Content-Disposition: form-data; name=TimeStamp

2007-08-30T10:20:34Z
--XbCY
Content-Type: text/plain; charset=utf-8
Content-Disposition: form-data; name=SenderID

HospitalA
--XbCY
Content-Type: text/plain; charset=utf-8
Content-Disposition: form-data; name=ReceiverID

PayerB
--XbCY
Content-Type: text/plain; charset=utf-8
Content-Disposition: form-data; name=CORERuleVersion

2.2.0
--XbCY
Content-Disposition: form-data; name=Payload; filename=276_5010.edi

ISA*00*~SE*16*0001~GE*1*1~IEA*1*191543498~
--XbCY--

Mein Controller-Code:

string payload = null;
NameValueCollection nvc = null;
string fname = null;
StringBuilder sb = new StringBuilder();
sb.AppendLine();
foreach (StreamContent item in provider.Contents)
{
    fname = item.Headers.ContentDisposition.FileName;
    if (!String.IsNullOrWhiteSpace(fname))
    {
        payload = item.ReadAsStringAsync().Result;
    }
    else
    {
        nvc = item.ReadAsFormDataAsync().Result;
    }
}
46
user2434400

Aktualisiert am 28.04.2015

Sie können einen benutzerdefinierten Anbieter basierend auf MultipartFormDataRemoteStreamProvider erstellen.
Beispiel:

public class CustomMultipartFormDataProvider : MultipartFormDataRemoteStreamProvider
{
    public override RemoteStreamInfo GetRemoteStream(HttpContent parent, HttpContentHeaders headers)
    {
        return new RemoteStreamInfo(
            remoteStream: new MemoryStream(),
            location: string.Empty,
            fileName: string.Empty);
    }
}

aktualisiert

Benutzerdefinierter speicherinterner MultiaprtFormDataStreamProvider:

public class InMemoryMultipartFormDataStreamProvider : MultipartStreamProvider
{
    private NameValueCollection _formData = new NameValueCollection();
    private List<HttpContent> _fileContents = new List<HttpContent>();

    // Set of indexes of which HttpContents we designate as form data
    private Collection<bool> _isFormData = new Collection<bool>();

    /// <summary>
    /// Gets a <see cref="NameValueCollection"/> of form data passed as part of the multipart form data.
    /// </summary>
    public NameValueCollection FormData
    {
        get { return _formData; }
    }

    /// <summary>
    /// Gets list of <see cref="HttpContent"/>s which contain uploaded files as in-memory representation.
    /// </summary>
    public List<HttpContent> Files
    {
        get { return _fileContents; }
    }

    public override Stream GetStream(HttpContent parent, HttpContentHeaders headers)
    {
        // For form data, Content-Disposition header is a requirement
        ContentDispositionHeaderValue contentDisposition = headers.ContentDisposition;
        if (contentDisposition != null)
        {
            // We will post process this as form data
            _isFormData.Add(String.IsNullOrEmpty(contentDisposition.FileName));

            return new MemoryStream();
        }

        // If no Content-Disposition header was present.
        throw new InvalidOperationException(string.Format("Did not find required '{0}' header field in MIME multipart body part..", "Content-Disposition"));
    }

    /// <summary>
    /// Read the non-file contents as form data.
    /// </summary>
    /// <returns></returns>
    public override async Task ExecutePostProcessingAsync()
    {
        // Find instances of non-file HttpContents and read them asynchronously
        // to get the string content and then add that as form data
        for (int index = 0; index < Contents.Count; index++)
        {
            if (_isFormData[index])
            {
                HttpContent formContent = Contents[index];
                // Extract name from Content-Disposition header. We know from earlier that the header is present.
                ContentDispositionHeaderValue contentDisposition = formContent.Headers.ContentDisposition;
                string formFieldName = UnquoteToken(contentDisposition.Name) ?? String.Empty;

                // Read the contents as string data and add to form data
                string formFieldValue = await formContent.ReadAsStringAsync();
                FormData.Add(formFieldName, formFieldValue);
            }
            else
            {
                _fileContents.Add(Contents[index]);
            }
        }
    }

    /// <summary>
    /// Remove bounding quotes on a token if present
    /// </summary>
    /// <param name="token">Token to unquote.</param>
    /// <returns>Unquoted token.</returns>
    private static string UnquoteToken(string token)
    {
        if (String.IsNullOrWhiteSpace(token))
        {
            return token;
        }

        if (token.StartsWith("\"", StringComparison.Ordinal) && token.EndsWith("\"", StringComparison.Ordinal) && token.Length > 1)
        {
            return token.Substring(1, token.Length - 2);
        }

        return token;
    }
}

Verwendung:

public async Task Post()
{
    if (!Request.Content.IsMimeMultipartContent("form-data"))
    {
        throw new HttpResponseException(HttpStatusCode.BadRequest);
    }

    var provider = await Request.Content.ReadAsMultipartAsync<InMemoryMultipartFormDataStreamProvider>(new InMemoryMultipartFormDataStreamProvider());

    //access form data
    NameValueCollection formData = provider.FormData;

    //access files
    IList<HttpContent> files = provider.Files;

    //Example: reading a file's stream like below
    HttpContent file1 = files[0];
    Stream file1Stream = await file1.ReadAsStreamAsync();
}
116
Kiran Challa