No output when executing python file from c#

Question

I build a Webscraper in python, which generates the right output when executed. Now I wanted to implement it to a C# project and it doesn´t work. I just don´t get any ouput from it. I tried finding a problem with printin things to labels in different steps but it seems to work fine. My python code:

import bs4
import requests
from bs4 import BeautifulSoup

r = requests.get("https://fred.stlouisfed.org/series/AAA")
soup = bs4.BeautifulSoup(r.text,"lxml")
soup_find = soup.find_all("div",{"class":"pull-left meta-col"})[0].find("span",{"class":"series-meta-observation-value"}).text
print(soup_find)

And my C# Code (in Visual Studio):

        private void cmd_scrape_Click(object sender, EventArgs e)
    {
        string fileName = @"My\path\to\Webscraper.py";
        Process p = new Process();
        p.StartInfo = new ProcessStartInfo(@"My\path\to\python.exe", fileName)
        {
            RedirectStandardOutput = true,
            UseShellExecute = false,
            CreateNoWindow = true
        };
        p.Start();
        lbl_Out.Text = "Starting...";
        string Output = p.StandardOutput.ReadToEnd();
        lbl_Out.Text = "Waiting for exit...";
        p.WaitForExit();
        lbl_Out.Text = "Done";
        lbl_Out.Text = Output;
    }

Answer 1

I can't directly answer to your question because I have no python installed and can't reproduce the problem. But I'll show how to do the same thing completely with C#.

I assume that the C# project is WinForms.

Install 2 NuGet packages (in Visual Studio menu Project -> Manage Nuget Packages)

• HtmlAgilityPack
• Fizzler.Systems.HtmlAgilityPack

First one provides HTML parser, 2nd provides an extension HtmlNode.QuerySelector. Query syntax for QuerySelector is almost the same as in JavaScript.

After installation add namespaces to the code.

using HtmlAgilityPack;
using HtmlDocument = HtmlAgilityPack.HtmlDocument; // overrides class name conflict with System.Windows.Forms.HtmlDocument
using Fizzler.Systems.HtmlAgilityPack;

And whole code of the project

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

    public Form1()
    {
        InitializeComponent();
    }

    private async void button1_Click(object sender, EventArgs e)
    {
        try
        {
            label1.Text = "Connecting";
            using (HttpResponseMessage response = await client.GetAsync("https://fred.stlouisfed.org/series/AAA", HttpCompletionOption.ResponseHeadersRead))
            {
                response.EnsureSuccessStatusCode();
                label1.Text = "Receiving data";
                string text = await response.Content.ReadAsStringAsync();
                HtmlDocument doc = new HtmlDocument();
                doc.LoadHtml(text);
                label1.Text = doc.DocumentNode.QuerySelector("div.pull-left.meta-col span.series-meta-observation-value").InnerText;
            }
        }
        catch (Exception ex)
        {
            label1.Text = "Error";
            MessageBox.Show(ex.Message + "\r\n\r\n" + ex.StackTrace);
        }
    }
}