WebClient.UploadValues Method (String, NameValueCollection)


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Uploads the specified name/value collection to the resource identified by the specified URI.

Namespace:   System.Net
Assembly:  System (in System.dll)

public byte[] UploadValues(
	string address,
	NameValueCollection data


Type: System.String

The URI of the resource to receive the collection.

Type: System.Collections.Specialized.NameValueCollection

The NameValueCollection to send to the resource.

Return Value

Type: System.Byte[]

A Byte array containing the body of the response from the resource.

Exception Condition

The address parameter is null.


The data parameter is null.


The URI formed by combining BaseAddress, and address is invalid.


data is null.


There was no response from the server hosting the resource.


An error occurred while opening the stream.


The Content-type header is not null or "application/x-www-form-urlencoded".

The UploadValues method sends a NameValueCollection to a server. This method blocks while uploading the data. To continue executing while waiting for the server's response, use one of the UploadValuesAsync methods.

If the underlying request is not understood by the server, the underlying protocol classes determine what occurs. Typically, a WebException is thrown with the Status property set to indicate the error.

If the Content-type header is null, the UploadValues method sets it to "application/x-www-form-urlencoded".

If the BaseAddress property is not an empty string ("") and address does not contain an absolute URI, address must be a relative URI that is combined with BaseAddress to form the absolute URI of the requested data. If the QueryString property is not an empty string, it is appended to address.

This method uses the STOR command to upload an FTP resource. For an HTTP resource, the POST method is used.


This member outputs trace information when you enable network tracing in your application. For more information, see Network Tracing in the .NET Framework.

The following code example gathers information from the user (name, age, and address) and posts the values to the server using UploadValues. Any response from the server is displayed on the console.

Console.Write("\nPlease enter the URI to post data to : ");
string uriString = Console.ReadLine();

// Create a new WebClient instance.
WebClient myWebClient = new WebClient();

// Create a new NameValueCollection instance to hold some custom parameters to be posted to the URL.
NameValueCollection myNameValueCollection = new NameValueCollection();

Console.WriteLine("Please enter the following parameters to be posted to the URL");
string name = Console.ReadLine();

string age = Console.ReadLine();

string address = Console.ReadLine();

// Add necessary parameter/value pairs to the name/value container.

Console.WriteLine("\nUploading to {0} ...",  uriString);
// 'The Upload(String,NameValueCollection)' implicitly method sets HTTP POST as the request method.            
byte[] responseArray = myWebClient.UploadValues(uriString,myNameValueCollection);

// Decode and display the response.
Console.WriteLine("\nResponse received was :\n{0}",Encoding.ASCII.GetString(responseArray));

.NET Framework
Available since 1.1
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