Here we will describe a simple procedure to make a request of type "multipart/form-data" from C# using the HttpWebRequest class. Taking as refence the article published in the web : Browsing_the_WEB_with_C_.asp .
The big problem of this type of request is how to prepare the data package that will be passed to the class. For this, the more easy way to do this is making a string with the data in text form. You will must be careful with this, because if you put wrong a character or separator the package wont get to destiny successfully.
The next method make this action about a parameters collection, these parameters can be different type, because by this way you will can sending the file content.
"cs">private string GetPostData()
{
string boundary = "--" + this._Boundary;
int arrReqs = this._ParamsCollection.Count * 5;
string[] auxReqBody = new string[arrReqs];
int count = 0;
foreach(ParamsStruct par in this._ParamsCollection)
{
auxReqBody[count] = boundary;
count++;
switch (par.Type)
{
case ParamsStruct.ParamType.File:
{
auxReqBody[count] = "Content-Disposition: file; name=\"" + par.Name + "\"; filename=\"" + par.GetOnlyFileName() + "\"";
count++;
auxReqBody[count] = "Content-Type: text/plain";
count++;
auxReqBody[count] = "";
count++;
auxReqBody[count] = par.StringValue;
count++;
break;
}
case ParamsStruct.ParamType.Parameter:
default:
{
auxReqBody[count] = "Content-Disposition: form-data; name=\"" + par.Name + "\"";
count++;
auxReqBody[count] = "";
count++;
auxReqBody[count] = par.StringValue;
count++;
break;
}
}
}
auxReqBody[count] = boundary;
count++;
string requestBody = String.Join("\r\n",auxReqBody);
return requestBody;
}
Then if we inform in the parameters collection : one parameter of type "Parameter", name "param1" and value "param1Value" and one parameter of type "File", name "file", file name "fileName1.txt" and value "Content of fileName1.txt", after run of this method you will obtain a text with this format:
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After this, we will use a method similar to this one, for sending the information to the required page.
"cs">public void PostData ()
{
//Set URL
Uri urlUri = new Uri(_URL);
//Encoding postData
ASCIIEncoding encoding = new ASCIIEncoding();
string postData = this.GetPostData();
byte[] buffer = encoding.GetBytes( postData );
// Prepare web request...
HttpWebRequest myRequest =(HttpWebRequest)WebRequest.Create(urlUri);
// We use POST ( we can also use GET )
myRequest.Method = this._Method;
myRequest.AllowWriteStreamBuffering = true;
// Set the content type to a FORM
string auxContent = this._ContentType;
if (this._Boundary.Length > 0)
auxContent += "boundary=" + this._Boundary;
myRequest.ContentType = auxContent;
// Get length of content
myRequest.Accept = this._Accept;
myRequest.ContentLength = buffer.Length;
// Get request stream
Stream newStream = myRequest.GetRequestStream();
// Send the data.
newStream.Write(buffer,0,buffer.Length);
// Close stream
newStream.Close();
_myHttpWebResponse= (HttpWebResponse)myRequest.GetResponse();
// Set the response to ResponseStream property
this._ResponseStream = _myHttpWebResponse.GetResponseStream();
}
For finishing this, we must process the request stream returned by the required page. In this case I declare one property inside class that transform the response stream to string.
"cs">public string ResponseString
{
get
{
string resultData = "";
StreamReader streamRead = new StreamReader( _ResponseStream );
Char[] readBuffer = new Char[256];
// Read from buffer
int count = streamRead.Read( readBuffer, 0, 256 );
while (count > 0)
{
// get string
resultData += new String( readBuffer, 0, count);
// Write the data
Console.WriteLine( resultData );
// Read from buffer
count = streamRead.Read( readBuffer, 0, 256);
}
// Release the response object resources.
streamRead.Close();
return resultData;
}
}
In simple way, this will adapt to another content type. Remember that the key is the form for load the data package.
For SSL page type see request_SSL_from_C_.asp
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