#Tauri sidecar issue: No output received

39 messages · Page 1 of 1 (latest)

gentle sentinel
#

Hi I am trying to get my tauri to work with a python script as a sidecar. Reason -> I want to run a python script that uses the users webcam to detect gestures to control the app.

To make it easy, I started with a sample project.

Pyhton script:

import sys 
import time

while True:   
    sys.stdout.write('Hello from python script from stdout')
    print("Hello from python script from console")
    time.sleep(1)

Converted it to a binary and followed the docs https://tauri.app/v1/guides/building/sidecar/

Src-tauri/main.rs:

// Prevents additional console window on Windows in release, DO NOT REMOVE!!
#![cfg_attr(not(debug_assertions), windows_subsystem = "windows")]

use tauri::{
  api::process::{Command, CommandEvent}
};

fn main() {
  tauri::Builder::default()
  .setup(|_app| {
    tauri::async_runtime::spawn(async move {
      let (mut rx, _child) = Command::new_sidecar("main")
        .expect("failed to setup `app` sidecar")
        .spawn()
        .expect("Failed to spawn packaged node");

      while let Some(event) = rx.recv().await {
        if let CommandEvent::Stdout(line) = event {
          println!("{}", format!("'{}'", line));
        }
      }
    });

    Ok(())
  })
    .run(tauri::generate_context!())
    .expect("error while running tauri application");
}

I am not getting any error message at all so I assume it runs the sidecar but I am not getting any output from the sidecar. Any reason why?

Embedding External Binaries | Tauri Apps

You may need to embed depending binaries to make your application work or prevent users from installing additional dependencies (e.g., Node.js or Python).

molten roost
#

how does the tauri.conf.json and Cargo.toml looks like.

how you invoke your command ... there some stuff missing.

gentle sentinel
#

Tauri.conf.json is like exacly like the docs and the cargo.toml , there is nothing that would change the situation, I wouldnt know what you are looking for there. It is a barebone tauri app

molten roost
#

sooo .... "binaries/main" is your python binary ?

and you need to add a feature in your cargo.toml

#

below "Running it from Rust"

Note that you must enable the process-command-api Cargo feature (Tauri's CLI will do this for you once you changed the config):

#

you need to call the command

like

import { Command } from '@tauri-apps/api/shell'

const command = Command.sidecar('binaries/main', [some, args]) // <- Select your python binarie you included
const output = await command.execute() // execute it.
gentle sentinel
#

But I dont want to run it from the front end

#

I want to run in in the setup function of the tauri backend

#

@molten roost I indeed needed to at process-command-api to cargo.toml but it is still not working when I call it from rust

molten roost
# 
      let (mut rx, _child) = Command::new_sidecar("main")
        .expect("failed to setup `app` sidecar")
        .args(["arg"])
        .spawn()
        .expect("Failed to spawn packaged node");
gentle sentinel
#

But I have no arguments to give it

#

@molten roost Can you reproduce the issue with my github repository?

#

@molten roost Okay so

#

I let the app run for a bit and after a while I get my output

#

But it is not instantaneous. Why is that ?

molten roost
#

you spawn a process and run it ... it takes a bit

gentle sentinel
#

it outputs like 20 console log at once

#

then it stops

#

then after a while again 20 console log at once

#

although my python script always waits for 1 second and then sends it

molten roost
#

overall you setup your app ... and when app is running your spawn the process ... thats why it takes time

#

20 console log ..... maybe because of your while loop in the python script ?

gentle sentinel
#

The issue is not the start up time. I am guessing that it has to do something with the while loop

#

I seems that tauri is ready the console logs from my python script but only outputs them when their buffer is full or something

#

That is why it takes a while and I get everything at once and then wait and then again everything at once, over and over

#

thats my guess

#

but now the question is why and how can I prevent this and get live the outputs from the python script

tender siren
#

can you try explictly writing a new line in your pythong code

#

like using your code from above: ```py
while True:
sys.stdout.write('Hello from python script from stdout\n')
print("Hello from python script from console\n")
time.sleep(1)

#

print should already include one but stdout.write probably doesn't. either way, try it with both

gentle sentinel
#

@tender siren Okay I will try and indeed the sys.stdout.write is not working, the print is enough.

#

Still no succes :/

#

I still receive everything in chunks

molten roost
#

write them to a buffer and then read the buffer

gentle sentinel
#

You have an example how?

#

@nocturne veldt You have any experience with this? I saw your youtube video about sidecarts.

gentle sentinel