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Calling a Python script from C# returns an empty output

I am creating a web application using ASP NET that runs on Windows Server 2012 using IIS 10. This application exposes a service at www.domain.com/service/execute which uses a python script executed using Python 3.9.13. Below I report the C# and Python code:
main.py
import pprint
pprint.pprint("Hello World!!")
ServiceController.cs
public class ServiceController : Controller {
public IActionResult Execute() {
var FileName = $#"C:\\path\\to\\python.exe";
var Arguments = $#"C:\\path\\to\\main.py";
var processStartInfo = new ProcessStartInfo() {
FileName = FileName,
Arguments = Arguments,
CreateNoWindow = true,
UseShellExecute = false,
RedirectStandardOutput = true,
RedirectStandardError = true,
};
using(var process = Process.Start(processStartInfo)) {
var taskError = process.StandardError.ReadToEndAsync();
var taskOutput = process.StandardOutput.ReadToEndAsync();
taskError.Wait();
taskOutput.Wait();
var errors = taskError.Result.Trim();
var output = taskOutput.Result.Trim();
return Ok(
$"FileName={FileName}" +
$"\n" +
$"Arguments={Arguments}" +
$"\n" +
$"errors={errors}" +
$"\n" +
$"output={output}"
);
}
}
}
Calling this service I don't get any errors or exceptions but the output is empty:
FileName=C:/path/to/python.exe
Arguments=C:/path/to/main.py
errors=
output=
If in the C# script I insert as Arguments a totally invented path to a non-existent python script I don't get any error/exception and the output is still empty.
I would expect an output like this:
FileName=C:/path/to/python.exe
Arguments=C:/path/to/main.py
errors=
output=Hello World!!

.py file executed by C# process not waiting to finish

I want to run .py file from my C# project, and get the result. The python script is making an API request, and returns an auth_key token, which I want to use in my C# code. The only problem is that, for some reason the C# code doesn't wait for the process to finish, and thus that not every account has auth_key. Here is my C# code.
private static void GenerateTokens()
{
var url = ConfigurationManager.AppSetting[GeSettingsNode() + ":ip"];
for (int i = 0; i < accounts.Count; i++)
{
ProcessStartInfo start = new ProcessStartInfo();
start.FileName = ConfigurationManager.AppSetting["PythonPath"];
start.Arguments = string.Format($"python_operation_processor.py {accounts[i].client_key_id} {accounts[i].key_sercret_part} {url}");
start.UseShellExecute = false;
start.RedirectStandardOutput = true;
Process process = Process.Start(start);
using (StreamReader reader = process.StandardOutput)
{
accounts[i].auth_key = reader.ReadToEnd().Trim();
}
}
}
And here is my Python script ( python_operation_processor.py )that's making the API requests.
if __name__ == '__main__':
client_key_id = sys.argv[1]
client_secret = sys.argv[2]
API_URL = sys.argv[3]
nonce = str(uuid.uuid4())
d = datetime.datetime.now() - datetime.timedelta(hours=3)
timestamp = d.strftime('%Y-%m-%dT%H:%M:%S.%f')[:-3] + 'Z'
signature = b64encode(hmac.new(b64decode(client_secret), msg=bytes(client_key_id + nonce + timestamp, 'utf-8'),
digestmod=hashlib.sha256).digest()).decode('utf-8')
r = requests.post(API_URL + '/v1/authenticate',
json={'client_key_id': client_key_id, 'timestamp': timestamp, 'nonce': nonce,
'signature': signature})
if r.status_code != 200:
raise Exception('Failed to authenticate: ' + r.text)
auth_token = r.json()['token']
print(auth_token)
Do you have any idea, how I can wait for the execution of every process, and get the token for every account ?

I recently created something similar and ended up with this because, whilst waiting for the process is easy, it is tricky to get the output stream filled correctly.
The method presented also allow you to display the output into a textblock or similar in your application.
If you use it like this, the token will be written to the StringBuilder, and used as return value.
private async Task<string> RunCommand(string fileName, string args)
{
var timeoutSignal = new CancellationTokenSource(TimeSpan.FromMinutes(3));
ProcessStartInfo start = new ProcessStartInfo();
start.FileName = fileName;
start.Arguments = string.Format("{0}", args);
start.RedirectStandardOutput = true;
start.RedirectStandardError = true;
start.UseShellExecute = false;
start.CreateNoWindow = true;
var sb = new StringBuilder();
using (Process process = new Process())
{
process.StartInfo = start;
process.OutputDataReceived += (sender, eventArgs) =>
{
sb.AppendLine(eventArgs.Data); //allow other stuff as well
};
process.ErrorDataReceived += (sender, eventArgs) => {};
if (process.Start())
{
process.EnableRaisingEvents = true;
process.BeginOutputReadLine();
process.BeginErrorReadLine();
await process.WaitForExitAsync(timeoutSignal.Token);
//allow std out to be flushed
await Task.Delay(100);
}
}
return sb.ToString();
}
To render this to a textblock in a UI application, you'll need to:
implement an event which signals a new line has been read, which means forwarding the process.OutputDataReceived event.
if your thinking about a live feed, make sure you flush the stdio buffer in python setting flush to true: print(""hello world"", flush=True)
If you're using an older .net version; you can implement the WaitForExitAsync as described here: https://stackoverflow.com/a/17936541/2416958 as an extention method:
public static class ProcessHelpers
{
public static Task<bool> WaitForExitAsync(this Process process, TimeSpan timeout)
{
ManualResetEvent processWaitObject = new ManualResetEvent(false);
processWaitObject.SafeWaitHandle = new SafeWaitHandle(process.Handle, false);
TaskCompletionSource<bool> tcs = new TaskCompletionSource<bool>();
RegisteredWaitHandle registeredProcessWaitHandle = null;
registeredProcessWaitHandle = ThreadPool.RegisterWaitForSingleObject(
processWaitObject,
delegate(object state, bool timedOut)
{
if (!timedOut)
{
registeredProcessWaitHandle.Unregister(null);
}
processWaitObject.Dispose();
tcs.SetResult(!timedOut);
},
null /* state */,
timeout,
true /* executeOnlyOnce */);
return tcs.Task;
}
}

Empty output when calling a python script in C# project

I would like to call a python script in my C# project , I'm using this function to do the job but unfortunately I didn't get any result and the result variable shows always an empty output. I would like to know what's the reason of this
public string RunFromCmd(string rCodeFilePath, string args)
{
string file = rCodeFilePath;
string result = string.Empty;
try
{
var info = new ProcessStartInfo(pythonPath);
info.Arguments = #"C:\Users\MyPc\ExternalScripts\HelloWorld.py" + " " + args;
info.RedirectStandardInput = false;
info.RedirectStandardOutput = true;
info.UseShellExecute = false;
info.CreateNoWindow = true;
using (var proc = new Process())
{
proc.StartInfo = info;
proc.Start();
proc.WaitForExit();
if (proc.ExitCode == 0)
{
result = proc.StandardOutput.ReadToEnd();
}
}
return result;
}
catch (Exception ex)
{
throw new Exception("R Script failed: " + result, ex);
}
}
Click Event ( Calling funtion )
private void Button1_Click(object sender, RoutedEventArgs e)
{
pythonPath = Environment.GetEnvironmentVariable("PYTHON_PATH");
RunFromCmd(pythonPath, "");
}
Python Script :
import sys
def main():
text = "Hello World"
return text
result = main()

I've fixed the issue by setting Copy if newer instead of Do Not Copy to HelloWorld.py Script

C# cannot call python and pass parameters

I am a newbie in programming, and I have an MVC project. I want to use C# call the Python py file and pass parameters in order to make a chart. I refer to this article How do I run a Python script from C#? . I have used this method to make lots of charts, and they can execute and pass parameters successfully. There's only two files cannot be successfully called and passed parameters, and I think it's Python has an error that can't call the py.
Here is a failure below. When I run proportion.py alone in Spyder, it can successfully use the Fixed parameters. BUT when i use C# to call it, there will be no response. The syntax in the file has been confirmed to be executed without problems, and methods i have been tried lots of methods, but still not resolved. Please save my projetct, I will be very thankful!!Thanks for any help.
Here is how i use C# to call Python below.
public ActionResult Index(string searchString, DateTime? startdate, DateTime? enddate)
{
run_sound("D:/Python/pie.py", "" + sd + "", "" + ed + "", "" + searchString + "");
run_Emoanalysis("picture/AAApy.py", "" + sd + "", "" + ed + "", "" + searchString + "");
run_proportion("D:/Microsoft Visual Studio/MVC project/MVC project/picture /proportion.py", "" + sd + "", "" + ed + "", "" + searchString + "");
}
//The following is the function of run_proportion,
//other functions(run_sound) are the same as this method, and carefully confirmed.
private string run_proportion(string cmd, string sdate, string edate, string condition)
{
ProcessStartInfo start = new ProcessStartInfo();
start.FileName = #"C:/Users/user/AppData/Local/Programs/Python/Python38-32/python.exe";
start.CreateNoWindow = true;
start.Arguments = string.Format("{0} {1} {2} {3}", cmd, sdate, edate, condition);
start.UseShellExecute = false;
start.RedirectStandardOutput = true;
using (Process process = Process.Start(start))
{
using (StreamReader reader = process.StandardOutput)
{
string result = reader.ReadToEnd();
//Console.Write(result);
process.WaitForExit();
return result;
}
}
}
Here is proportion.py below that cannot be called and executed BY C#.
sd= sys.argv[1]
ed = sys.argv[2]
cdn = sys.argv[3]
sqlcom = "SELECT COUNT(DISTINCT url) FROM JIEBA WHERE (title LIKE '%" +str(cdn)+ "%') AND (post BETWEEN '" +str(sd)+ "' AND '" +str(ed)+ "')"
sqlcom2 = "SELECT COUNT(DISTINCT url) as KeyWordCount FROM JIEBA WHERE (title LIKE '%" +str(cdn)+ "%')"
df = pd.read_sql(sqlcom, con=cnxn)
df1 = np.array(df)
df0 = df1.tolist()
df2 = pd.read_sql(sqlcom2, con=cnxn)
df3 = np.array(df2)
df4 = df3.tolist()
df5 = str(df4[0][0])
print(df5)
df6 = str(df0[0][0])
print(df6)
c = int(df5)-int(df6)
# =============================================================================
count = float(df5)/float(df5)
print(count)
#
keyword = float(df6)/float(df5)
print(keyword)
#
keyword2 = str(round(float(df6)/float(df5)*100,2))+'%'
print(keyword2)
#
count2 = str(round((1-float(df6)/float(df5))*100,2))+'%'
print(count2)
# Change color
fig = plt.figure(figsize = (7,5))
ax = fig.add_subplot(111)
squarify.plot(sizes=[int(c),int(df6)], label=['期間"外"所佔筆數', '查詢後所佔比數'],value =(str(c)+'筆/'+str(df5)+'筆'+'\n'+'佔　'+str(count2),str(df6)+'筆/'+str(df5)+'筆'+'\n'+'佔　'+str(keyword2)), color=["red","blue"], alpha=.4)
plt.rcParams['font.sans-serif'] = 'Microsoft YaHei'
plt.rcParams['axes.unicode_minus'] = False
ax.set_title('關鍵字搜尋期間所佔比例',fontsize = 18)
plt.axis('off')
plt.tight_layout()
plt.savefig("D:\Microsoft Visual Studio\MVC project\MVC project\picture\keyproportion.png")

Also had some issues with running python, first would suggest replacing quotes in strings with a variable since it makes tracking them easier
var quote = '"';
also after doing the whole string do a
var commandUnescaped = Regex.Unescape(command);
pasting my way to call commands in case you want it, need to adapt it to windows , but same logic:
private (bool,string,string) RunCommand(string command, string args)
{
args = args.Replace("\"", "\\\"");
var process = new Process()
{
StartInfo = new ProcessStartInfo
{
FileName = "/bin/bash",
Arguments = $"-c \"{args}\"",
RedirectStandardOutput = true,
RedirectStandardError = true,
UseShellExecute = false,
CreateNoWindow = true,
}
};
process.Start();
string output = process.StandardOutput.ReadToEnd();
string error = process.StandardError.ReadToEnd();
process.WaitForExit();
if (string.IsNullOrEmpty(error))
{
return (true,output,error);
}
else
{
return (false,output,error);
}
}

Calling named pipe of Dropbox to get status: Error: read EPIPE

I have working Python script that checks local Windows Dropbox application sync status that i try to port to nodejs (to use in Electron) .
The problem is that i get:
events.js:141
throw er; // Unhandled 'error' event
^
Error: read EPIPE
at exports._errnoException (util.js:907:11)
at Pipe.onread (net.js:557:26)
when i try my node script.
Here's the python script:
import win32pipe, win32ts, win32api, pywintypes, struct, sys
yourUsername = "YourUsername"
def dropbox_path_status(pathname):
return ['dropbox not running','not in dropbox','up to date','syncronising','sync problem'][dropbox_path_status_code(pathname)+1]
def dropbox_path_status_code(pathname):
processid = win32api.GetCurrentProcessId()
threadid = win32api.GetCurrentThreadId()
request_type = 1
wtf = 0x3048302
pipename = r'\\.\pipe\DropboxPipe_' + str(win32ts.ProcessIdToSessionId(processid))
request = (struct.pack('LLLL', wtf, processid, threadid, request_type) + pathname.encode('utf-16le') + (chr(0)*540))[0:540]
try:
response = win32pipe.CallNamedPipe(pipename, request, 16382, 1000)
except pywintypes.error, err:
if err[0] == 2:
return -1
else:
raise
else:
return int(response[4:-1])
print dropbox_path_status("C:\Users\"+yourUsername+"\Dropbox")
Here's my node script
var net = require('net');
var ffi = require('ffi');
var ref = require('ref');
var BufferStream = require('node-bufferstream')
var PIPE_PATH = "\\\\.\\pipe\\DropboxPipe_1"
var UserName = "YourUsername"
var L = console.log;
var SessionId = ref.alloc("uint");
var kernel32 = new ffi.Library("kernel32",{
GetLastError:['string',[]],
GetCurrentProcessId: ['int',[]] ,
GetCurrentThreadId: ['int',[]],
ProcessIdToSessionId: ['bool',['int','uint *']],
CallNamedPipeA:['bool',[]]
});
var RequestInfo = 0x3048302;
var ProcessId = kernel32.GetCurrentProcessId();
var ThreadId = kernel32.GetCurrentThreadId();
var RequestType =1;
var dropbox = ref.types.void;
if(!kernel32.ProcessIdToSessionId(ProcessId,SessionId )){
console.log(kernel32.GetLastError());
}
else{
console.log(SessionId);
SessionId.type = ref.types.int;
SessionIdInt = SessionId.deref();
console.log(SessionIdInt);
}
var TestBufferIn = new Buffer(16+724);
TestBufferIn.writeUInt32LE(RequestInfo, 0);
TestBufferIn.writeUInt32LE(ProcessId, 4);
TestBufferIn.writeUInt32LE(ThreadId, 8);
TestBufferIn.writeUInt32LE(RequestType, 12);
//TestBufferIn.writeUInt32LE(1234567, 600);
console.log(TestBufferIn.length)
var mypath = "C:/Users/"+UserName+"/Dropbox/"
TestBufferIn.write(mypath,16,162,"utf-16le")
stream = new BufferStream(TestBufferIn);
var L = console.log;
var client = net.createConnection({ path: '\\\\.\\pipe\\DropboxPipe_1'}, function () { console.log('connected');
client.write(TestBufferIn, ()=>{
console.log("write callback")
});
})
client.on('data', function(data) {
L('Client: on data:', data.toString());
client.end('Thanks!');
});
client.on('end', function() {
L('Client: on end');
})
Any idea why the error appears?
EDIT
When i write with string (instead of buffer) i get same error.
var client = net.createConnection({ path: '\\\\.\\pipe\\DropboxPipe_1'}, function () { console.log('connected');
client.write("hello", ()=>{
console.log("write callback"); //this is written in console
});
});