CODEWITHSUNDEEP
javascriptnode.jsreactjschild-process
Yash Vishe
Yash Vishe

Reputation: 61

How to use child process and spawn in React.js webapp

I am making this web app about bookstore which recommends books based on book user selects. I want it to run a python script and for that, I have used child process looking at this thread How to call a Python function from Node.js

Here's the code:

const spawn = require("child_process").spawn;
const pythonProcess = spawn('python',["../../../python/book_recommendation.py","Timeline"]);

const Recommendations = pythonProcess.stdout.on('data', (data) => {
    console.log(data);
});

module.exports = Recommendations;

I want this code to run when I click on the product and get directed to productScreen page. But I get the error "TypeError: Spawn is not a function". With some google searching, I found out that I m calling this function through react and not node.js. I m using react as frontend and node.js as backend. How can I solve this problem?

Here's how I imported this in react ProductScreen.js page

import { Recommendations } from "../machine-learning/recommendation_engine"

Here's the file structure of my project

enter image description here

Update:

const spawn = require("child_process").spawn;
const pythonProcess = spawn('python',["../python/book_recommendation.py","Timeline"]);
app.get("/product/:id", (req, res) => {
  pythonProcess.stdout.on('data', (data) => {
      console.log(data);
  });
});

I moved the above code in server.js backend folder now. How do I call it?

Upvotes: 1

Views: 2499

Answers (1)

The Fool
The Fool

Reputation: 20537

I don't think it's good architecture wise. But if you insist on doing it that way, then you need to spawn the child process when the requests hit. You could then pipe its output to the response stream. In this example I am using pipeline which is somewhat safer than mystream.pipe.

const spawn = require("child_process").spawn;
const { pipeline } = require('stream');

app.get("/python-process", (request, response) => {
    const pythonProcess = spawn('python', [
        "../python/book_recommendation.py",
        "Timeline"
    ]);
    // pipe the python process stream into the response stream
    pipeline(pythonProcess, response, (err) => err && console.warn(err));
});

Note, I haven't tested this, but it is the gist of how you could go about it.

Upvotes: 1

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