Note: Advice in this article will only work for DotNetBrowser 1.
See the corresponding article for DotNetBrowser 2 here.

DotNetBrowser API provides functionality that allows intercepting POST / PUT / PATCH requests , accessing and modifying POST / PUT / PATCH upload data before it will be sent to a web server. POST/PUT/PATCH upload data can be one of the following types:


Depending on the upload data type, you can use different strategies for accessing and modifying upload data. The following sample demonstrates how to do this:


using DotNetBrowser;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace PostDataSample
    /// <summary>
    /// This sample demonstrates how to read and modify POST parameters using NetworkDelegate.
    /// </summary>
    class Program
        static void Main(string[] args)
            LoggerProvider.Instance.LoggingEnabled = true;
            LoggerProvider.Instance.ConsoleLoggingEnabled = true;

            Browser browser = BrowserFactory.Create();
            BrowserContext browserContext = browser.Context;
            NetworkService networkService = browserContext.NetworkService;
            networkService.NetworkDelegate = new SampleNetworkDelegate();

            browser.LoadURL(new LoadURLParams("http://localhost/", "key=value", "Content-Type:text/plaint\n"));

        private class SampleNetworkDelegate : DefaultNetworkDelegate
            public override void OnBeforeURLRequest(BeforeURLRequestParams parameters)
                if ("POST" == parameters.Method)
                    PostData post = parameters.PostData;
                    PostDataContentType contentType = post.ContentType;
                    if (contentType == PostDataContentType.FORM_URL_ENCODED)
                        FormData postData = (FormData)post;
                        postData.SetPair("key1", "value1", "value2");
                        postData.SetPair("key2", "value2");
                    else if (contentType == PostDataContentType.MULTIPART_FORM_DATA)
                        MultipartFormData postData = (MultipartFormData)post;
                        postData.SetPair("key1", "value1", "value2");
                        postData.SetPair("key2", "value2");
                        postData.SetFilePair("file3", "C:\\");
                    else if (contentType == PostDataContentType.PLAIN_TEXT)
                        RawData postData = (RawData)post;
                        postData.Data = "raw data";
                    else if (contentType == PostDataContentType.BYTES)
                        BytesData data = (BytesData)post;
                        data.Data = Encoding.UTF8.GetBytes("My data");
                    parameters.PostData = post;


Imports System.Text
Imports DotNetBrowser

Module Module1

    Sub Main()
        LoggerProvider.Instance.LoggingEnabled = True
        LoggerProvider.Instance.ConsoleLoggingEnabled = True

        Dim browser As Browser = BrowserFactory.Create()
        Dim browserContext As BrowserContext = browser.Context
        Dim networkService As NetworkService = browserContext.NetworkService
        networkService.NetworkDelegate = New SampleNetworkDelegate()

        browser.LoadURL(New LoadURLParams("http://localhost/",
                                          "key=value", "Content-Type:text/plaint\n"))
    End Sub

    Friend Class SampleNetworkDelegate
        Inherits DefaultNetworkDelegate
        Overrides Sub OnBeforeURLRequest(parameters As BeforeURLRequestParams)
            If ("POST" Is parameters.Method) Then
                Dim post As PostData = parameters.PostData
                Dim contentType As PostDataContentType = post.ContentType

                If (contentType = PostDataContentType.FORM_URL_ENCODED) Then
                    Dim postData As FormData = CType(post, FormData)
                    postData.SetPair("key1", "value1", "value2")
                    postData.SetPair("key2", "value2")
                ElseIf (contentType = PostDataContentType.MULTIPART_FORM_DATA) Then
                    Dim postData As MultipartFormData = CType(post, MultipartFormData)
                    postData.SetPair("key1", "value1", "value2")
                    postData.SetPair("key2", "value2")
                    postData.SetFilePair("file3", "C:\\")
                ElseIf (contentType = PostDataContentType.PLAIN_TEXT) Then
                    Dim postData As RawData = CType(post, RawData)
                    postData.Data = "raw data"
                ElseIf (contentType = PostDataContentType.BYTES) Then
                    Dim data As BytesData = CType(post, BytesData)
                    data.Data = Encoding.UTF8.GetBytes("My data")
                End If
                parameters.PostData = post
            End If
        End Sub
    End Class
End Module