C# Facing problem to read ajax data using web browser control

问题

This is a web site https://www.wsj.com/news/types/newsplus whose data is getting loaded by ajax at runtime. i have to read all article title text. from morning i tried lots of code but still no code worked because data is getting load by ajax.

This is my code which i tried.

HtmlDocument hd = GetHtmlAjax(new Uri("https://www.wsj.com/news/types/newsplus"), 300, true);
ParseData(hd);


HtmlElementCollection main_element = hd.GetElementsByTagName("h3");
if (main_element != null)
{
    foreach (HtmlElement element in main_element)
    {
        string cls = element.GetAttribute("className");
        if (String.IsNullOrEmpty(cls) || !cls.Equals("WSJTheme--headline--unZqjb45 undefined WSJTheme--heading-3--2z_phq5h typography--serif-display--ZXeuhS5E"))
            continue;

        HtmlElementCollection childDivs = element.Children.GetElementsByName("a");
        foreach (HtmlElement childElement in childDivs)
        {
            //grab links and other stuff same way
            string linktxt = childElement.InnerText;
        }
    }
}           


WebBrowser wb = null;
public HtmlDocument GetHtmlAjax(Uri uri, int AjaxTimeLoadTimeOut,bool loadurl)
{
    if (loadurl)
    {
            wb = new WebBrowser();
            wb.ScriptErrorsSuppressed = true;
            wb.Navigate(uri);
    }

    while (wb.ReadyState != WebBrowserReadyState.Complete)
        Application.DoEvents();

    Thread.Sleep(AjaxTimeLoadTimeOut);
    Application.DoEvents();
    return wb.Document;
}

i follow many links to handle this issue but fail. these are the links i followed.

htmlagilitypack and dynamic content issue Get HTML in C# from page that Loads Dynamic Data Retrieve ajax/JavaScript return results from webpage in c#

How to extract dynamic ajax content from a web page

please some tell me what to change in my code to parse title link text. thanks

Post code from @aepot

private static HttpClient client = new HttpClient();

        private static async Task<T> GetJsonPageAsync<T>(string url)
        {
            using (HttpResponseMessage response = await client.GetAsync(url, HttpCompletionOption.ResponseHeadersRead))
            {
                response.EnsureSuccessStatusCode();
                string text = await response.Content.ReadAsStringAsync();
                return JsonConvert.DeserializeObject<T>(text);
            }
        }

        private async void button1_Click(object sender, EventArgs e)
        {
            try
            {
                dynamic newsList = await GetJsonPageAsync<dynamic>("https://www.wsj.com/news/types/newsplus?id={%22query%22:%22type:=\\%22NewsPlus\\%22%22,%22db%22:%22wsjie,blog,interactivemedia%22}&type=search_collection");
                List<Task<dynamic>> tasks = new List<Task<dynamic>>();
                foreach (dynamic item in newsList.collection)
                {
                    string strUrl = "https://www.wsj.com/news/types/newsplus?id=" + item.id + "&type=article";
                    tasks.Add(GetJsonPageAsync<dynamic>(strUrl));

                    //tasks.Add(GetJsonPageAsync<dynamic>($"https://www.wsj.com/news/types/newsplus?id={item.id}&type=article"));
                }

                dynamic[] newsDataList = await Task.WhenAll(tasks);
                foreach (dynamic newItem in newsDataList)
                {
                    //Console.WriteLine(newItem.data.headline);
                    //Console.WriteLine(newItem.data.url);

                    txtData.Text += newItem.data.headline + System.Environment.NewLine;
                    txtData.Text += new string('-', 200); + System.Environment.NewLine;
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
        }

回答1:

AJAX is simple GET or POST request.

Using regular Browser dev tools I've found that page sends simple GET request and receive JSON data. JSON can be deserealized or explored via reader.

For JSON parsing i used Newtonsoft.Json NuGet package

Here's simple example based on WinForms app.

public partial class Form1 : Form
{
    private static readonly HttpClient client = new HttpClient();

    private async Task<T> GetJsonPageAsync<T>(string url)
    {
        using (HttpResponseMessage response = await client.GetAsync(url, HttpCompletionOption.ResponseHeadersRead))
        {
            response.EnsureSuccessStatusCode();
            string text = await response.Content.ReadAsStringAsync();
            return JsonConvert.DeserializeObject<T>(text);
        }
    }

    public Form1()
    {
        InitializeComponent();
        ServicePointManager.DefaultConnectionLimit = 10; // to make it faster
        ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
    }

    private async void button1_Click(object sender, EventArgs e)
    {
        try
        {
            dynamic newsList = await GetJsonPageAsync<dynamic>("https://www.wsj.com/news/types/newsplus?id={%22query%22:%22type:=\\%22NewsPlus\\%22%22,%22db%22:%22wsjie,blog,interactivemedia%22}&type=search_collection");
            List<Task<dynamic>> tasks = new List<Task<dynamic>>();
            foreach (dynamic item in newsList.collection)
            {
                tasks.Add(GetJsonPageAsync<dynamic>($"https://www.wsj.com/news/types/newsplus?id={item.id}&type=article"));
            }
            dynamic[] newsDataList = await Task.WhenAll(tasks);
            foreach (dynamic newItem in newsDataList)
            {
                textBox1.Text += newItem.data.headline + Environment.NewLine;
                textBox1.Text += new string('-', 200) + Environment.NewLine;
            }
        }
        catch (Exception ex)
        {
            textBox1.Text = ex.Message;
        }
    }
}

UPD: Added fix for .NET Framework 4.5.2

来源：https://stackoverflow.com/questions/62851819/c-sharp-facing-problem-to-read-ajax-data-using-web-browser-control