Title: multipart/form-data function
Post by: Dany on November 06, 2014, 01:45:56 PM
Hi! I have written a small unit to help me post data to servers expecting a HTML form. Shown below, (i have stripped away some very specific stuff so it might not compile), is the general idea and it seems to work pretty well. If anyone cares to comment about this - i have a feeling it can be improved - i'd appreciate it. Especially how i have used the various RTC data types and Info objects... type
TClientUtilsEventClass = class
private
class procedure PostMultipartBeginRequest(Sender: TRtcConnection);
class procedure PostMultipartDataSent(Sender: TRtcConnection);
class procedure PostMultipartDataReceived(Sender: TRtcConnection);
end;
const
CR = #$0d;
LF = #$0a;
CRLF = CR + LF;
C64k = 65536;
class procedure TClientUtilsEventClass.PostMultipartBeginRequest(Sender: TRtcConnection);
var
Cli: TRtcDataClient absolute Sender;
begin
Cli.WriteHeader;
end;
class procedure TClientUtilsEventClass.PostMultipartDataSent(Sender: TRtcConnection);
var
lSize: int64;
Cli: TRtcDataClient absolute Sender;
begin
if Cli.Request.ContentLength > Cli.Request.ContentOut then
begin
lSize := Cli.Request.ContentLength - Cli.Request.ContentOut;
if lSize > C64k then lSize := C64k;
Cli.Write(RtcBytesToString(Copy(Cli.Request.Info.asByteArray['payload'], Cli.Request.ContentOut, lSize)));
end;
end;
class procedure TClientUtilsEventClass.PostMultipartDataReceived(Sender: TRtcConnection);
var
Cli: TRtcDataClient absolute Sender;
begin
if Cli.Response.Done then
Cli.Info['response'] := Cli.Read;
end;
function PostHTTPMultipart(const aCommand: string; lAttachments: TStrings): Variant;
procedure AddFile(aPayload: TRtcHugeString; aBound: RtcString; aFileName: string);
begin
aPayload.Add('--' + aBound + CRLF);
aPayload.Add(Utf8Encode('content-disposition: form-data; name="datafile"; filename="' + aFileName +'"') + CRLF);
aPayload.Add(Utf8Encode('content-type: application/octet-string') + CRLF + CRLF);
aPayload.Add(Read_file(aFileName));
aPayload.Add(CRLF);
end;
procedure AddField(aPayload: TRtcHugeString; aBound: RtcString; aFieldName, aFieldContent: string);
begin
aPayload.Add('--' + aBound + CRLF);
aPayload.Add(Utf8Encode('content-disposition: form-data; name="' + aFieldName + '"') + CRLF + CRLF);
aPayload.Add(Utf8Encode(aFieldContent));
aPayload.Add(CRLF);
end;
var
I: Integer;
lPostMultipartRequest: TRtcDataRequest;
lPostMultipartHttpClient: TRtcHttpClient;
lPayload: TRtcHugeString;
lBound: RtcString;
begin
lPayload := TRtcHugeString.Create;
lPostMultipartRequest := TRtcDataRequest.Create(nil);
lPostMultipartHttpClient := TRtcHttpClient.Create(nil);
try
with lPostMultipartHttpClient do
begin
AutoConnect := true;
Blocking := true;
ReconnectOn.ConnectLost := true;
ServerAddr := 'www.aserver.com'; //GUploadUtilsServerAddress;
ServerPort := '80'; //GUploadUtilsServerPort;
UseSSL := false; //GUploadUtilsUseSSL;
end;
lBound := IntToHex(Random(MaxInt), 8) + '_MySystem_boundary';
with lPostMultipartRequest do
begin
Client := lPostMultipartHttpClient;
OnBeginRequest := TClientUtilsEventClass.PostMultipartBeginRequest;
OnDataSent := TClientUtilsEventClass.PostMultipartDataSent;
OnDataReceived := TClientUtilsEventClass.PostMultipartDataReceived;
Request.Method := 'POST';
Request.FileName := '/' + aCommand;
Request.Host := lPostMultipartHttpClient.ServerAddr + ':' + lPostMultipartHttpClient.ServerPort;
// Request.Value[''] / Request.Cookies / et. al.
// Payload/Content Body call once for each field
AddField(lPayload, lBound, 'form_field_name', 'Form field value');
// Attachments...
for I := 0 to lAttachments.Count - 1 do
begin
AddFile(lPayload, lBound, lAttachments[I]);
end;
lPayload.Add('--' + lBound + '--' + CRLF);
Request.Info.asByteArray['payload'] := lPayload.GetEx;
Request.ContentLength := lPayload.Size;
Request.ContentType := 'multipart/form-data; boundary=' + lBound;
Post;
end;
with lPostMultipartHttpClient do
begin
DisconnectNow;
if not Info.isNull['response'] then
Result := Info['response'];
end;
end;
finally
lPostMultipartHttpClient.Free;
lPostMultipartRequest.Free;
lPayload.Free;
end;
end;
TIA, /Dany
Title: Re: multipart/form-data function
Post by: D.Tkalcec (RTC) on November 08, 2014, 12:42:08 PM
I haven't analyzed every single line of your code in detail, but here are some optional improvement suggestions in regards to RTC component and class usage:
1. Instead of using Cli.Write(RtcBytesToString(...)), which is converting a byte array to a string just to be converted back to a byte array inside the Write method (because RTC SDK is using RtcByteArray internally since v6.0), I would recommend using the Cli.WriteEx method when your source is a byte array. If a result of the Copy() function is not accepted as a parameter to the WriteEx method, an explicit typecast to RtcBytesArray should do the trick: Cli.WriteEx(RtcByteArray(...));
2. Do not use the Variant type, unless you absolutely have to. Conversions to and from Variant can be expensive, CPU and Memory-wise. So ... instead of using Cli.Info['response']:=Cli.Read, I would recommend using Cli.Info.asString['response']:=Cli.Read if you want your PostHTTPMultiPart function to return a RtcString, or Cli.Info.asByteArray['response']:=Cli.ReadEx if you want your PostHTTPMultiPart function to return a RtcByteArray. This is not absolutely necessary, but it avoids implicit type conversions.
3. After placing the request into the request queue using the Post method, use the WaitForCompletion method if you want to wait for a response from the Server before continuing. This will ensure that your implementation works on all platforms in single-threaded and multi-threaded mode, independent of the underlying API. Otherwise, you are forced to use a blocking API in single-threaded mode (as you did in your example).
Best Regards,
Danijel Tkalcec
Title: Re: multipart/form-data function
Post by: Dany on November 09, 2014, 01:51:57 PM
Brilliant! Your input is much appreciated.
/Dany
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