运行一个 python 脚本，在 React 应用程序的节点 js 服务器中创建一个数据库

Question

I need to run a python script on clicking a button in React application. I am using Node to run python script. The python script creates a sqlite3 database and does not print anything. How can I do this operation? If I am just printing anything from this script then i can get it through node API call but if I am running my original script, I am getting nothing, the database is not getting created.

My node server.js file is as below -

    const express = require('express');

    const app = express();

    app.get('/api/python', function (req, res) {
      var dataToSend;
      var spawn = require('child_process').spawn;
      var process = spawn('python', ['./projectdm.py']);
      process.stdout.on('data', function (data) {
        res.send(data.toString());
      });
      process.on('close', (code) => {
        console.log(`child process close all stdio with code ${code}`);
        console.log(dataToSend)
        // send data to browser
      });
    });

    app.listen(8080, () => {
        console.log('Server listening on the port 8080');
    });

My react application function which is called on button click and calls the node API, is as follows -

    onProcessHandler = () => {
            console.log('started');
            axios.get("http://localhost:8080/api/python")
            .then(res => { 
                console.log(res.data);
                this.setState({jsonData: res.data});
                console.log('Processing success')
            })
            .catch(err => { 
                console.log('Processing fail')
            })
            console.log('ended');
    }

My python script file is as follows -

import sqlite3
import pandas as pd

conn = sqlite3.connect('data.db')  
c = conn.cursor() 
c.execute(''' SELECT count(name) FROM sqlite_master WHERE type='table' AND name='hotel_record_historical'; ''')

if (c.fetchone()[0]==0) : 
    c.execute('''CREATE TABLE hotel_record_historical ([generated_id] INTEGER PRIMARY KEY, [Customer Name] text, [Aadhar no] text, [Contact no] text, [Address(House No, Street)] text, [City of Residence] text, [State of Residence] text, [City of Hotel] text, [State of Hotel] text, [Stay Date] date);''')
    read_hist_hotel=pd.read_csv(r'central_hotel_record_historical.csv')
    read_hist_hotel.to_sql('hotel_record_historical', conn, if_exists='append', index = False)
    conn.commit()


c.execute(''' SELECT count(name) FROM sqlite_master WHERE type='table' AND name='hotel_record_current' ;''')

if c.fetchone()[0]==0 : 
    c.execute('''CREATE TABLE hotel_record_current ([generated_id] INTEGER PRIMARY KEY, [Customer Name] text, [Aadhar no] text, [Contact no] text, [Address(House No, Street)] text, [City of Residence] text, [State of Residence] text, [City of Hotel] text, [State of Hotel] text, [Stay Date] date);''')
    read_cur_hotel = pd.read_csv (r'central_hotel_record_current.csv')
    read_cur_hotel.to_sql('hotel_record_current', conn, if_exists='append', index = False)
    conn.commit()


c.execute(''' SELECT count(name) FROM sqlite_master WHERE type='table' AND name='fir_record_historical' ;''')

if c.fetchone()[0]==0 : 
    c.execute('''CREATE TABLE fir_record_historical([Complainant Name] text, [Aadhar no] text, [Mobile No] text, [Incident Date] date, [Report Date] date);''')
    read_hist_fir = pd.read_csv (r'FIR_stolen_no_historical.csv')
    read_hist_fir.to_sql('fir_record_historical', conn, if_exists='append', index = False)
    conn.commit()


    
c.execute(''' SELECT count(name) FROM sqlite_master WHERE type='table' AND name='fir_record_current' ;''')

if c.fetchone()[0]==0 :  
    c.execute('''CREATE TABLE fir_record_current([Complainant Name] text, [Aadhar no] text, [Mobile No] text, [Incident Date] date, [Report Date] date);''')
    read_cur_fir = pd.read_csv (r'FIR_stolen_no_current.csv')
    read_cur_fir.to_sql('fir_record_current', conn, if_exists='append', index = False)
    conn.commit()
  
    
c.execute(''' SELECT count(name) FROM sqlite_master WHERE type='table' AND name='Registered_numbers' ;''')

if c.fetchone()[0]==0 :
    c.execute('''CREATE TABLE Registered_numbers([generated_id] INTEGER PRIMARY KEY, [Name] text, [Mobile no] text, [Aadhar no] text);''')
    read_registered = pd.read_csv (r'registered_phone_records.csv')
    read_registered.to_sql('Registered_numbers', conn, if_exists='append', index = False)
    conn.commit()

    
conn.commit()






import sqlite3
import pandas as pd
from pandas import DataFrame
conn = sqlite3.connect('data.db')  
c = conn.cursor()
c.execute(''' SELECT count(name) FROM sqlite_master WHERE type='table' AND name='Mediator' ''')

if c.fetchone()[0]==0 :
    
        # Crating Mediator DB
        c.execute('''CREATE TABLE Medium AS SELECT * FROM hotel_record_historical WHERE hotel_record_historical.[Contact no] IN (SELECT [Mobile No] FROM fir_record_historical);''')
        c.execute('''CREATE TABLE Medium2 AS SELECT Medium."Customer Name", Medium."Aadhar no", Medium."Contact no", Medium."Address(House No, Street)", Medium."City of Residence", Medium."State of Residence", Medium."City of Hotel", Medium."State of Hotel", Medium."Stay Date" FROM (Medium INNER JOIN fir_record_historical ON (fir_record_historical.[Mobile No]= Medium.[Contact no])) WHERE (SELECT (julianday(Medium.[Stay Date]) - julianday(fir_record_historical.[Report Date]))<90);''')
        c.execute('''CREATE TABLE Medium3 AS SELECT Medium."Customer Name", Medium."Aadhar no", Medium."Contact no", Medium."Address(House No, Street)", Medium."City of Residence", Medium."State of Residence", Medium."City of Hotel", Medium."State of Hotel", Medium."Stay Date" FROM (Medium INNER JOIN fir_record_historical ON (fir_record_historical.[Mobile No]= Medium.[Contact no])) WHERE (( SELECT (julianday(Medium.[Stay Date]) - julianday(fir_record_historical.[Report Date]))) BETWEEN 90 AND 180) AND (Medium.[Contact no] NOT IN (SELECT [Mobile no] FROM Registered_numbers));''')
        c.execute('''DROP TABLE Medium;''')
        c.execute('''ALTER TABLE Medium2 RENAME TO Mediator;''')
        c.execute('''INSERT INTO Mediator SELECT * FROM Medium3;''')
        c.execute('''DROP TABLE Medium3;''')
        
        # Adding columns for Mediator DB
        c.execute('''ALTER TABLE Mediator ADD COLUMN score REAL;''')
        c.execute('''ALTER TABLE Mediator ADD COLUMN c_residence REAL;''')
        c.execute('''ALTER TABLE Mediator ADD COLUMN c_hotel REAL;''')
        c.execute('''ALTER TABLE Mediator ADD COLUMN c_dup_cont_add REAL;''')
        c.execute('''ALTER TABLE Mediator ADD COLUMN Reason VARCHAR(500);''')
        c.execute('''UPDATE Mediator SET Reason="";''')
        
        #Set score based on state of residence:
        c.execute('''UPDATE Mediator SET c_residence=round(7.0/69, 4) WHERE [State of Residence] IN ("Arunachal Pradesh", "Assam", "Manipur", "Meghalaya", "Mizoram", "Nagaland");''')
        c.execute('''UPDATE Mediator SET c_residence=round(10.0/69, 4) WHERE [State of Residence] = "Jammu and Kashmir";''')
        c.execute('''UPDATE Mediator SET c_residence=round(3.0/69, 4) WHERE [State of Residence] IN ("Andhra Pradesh", "Chhattishgarh", "Jharkhand", "Odisha", "Bihar");''')
        c.execute('''UPDATE Mediator SET c_residence=round(2.0/69, 4) WHERE [State of Residence] = "Punjab";''')
        c.execute('''UPDATE Mediator SET c_residence=round(0.0/69, 4) WHERE [c_residence] IS NULL;''')
        c.execute('''UPDATE Mediator SET Reason=Reason || "Person resides in " || [State of Residence] WHERE [c_residence]!=0.0;''')
        
        #Set score based on state of hotel:
        c.execute('''UPDATE Mediator SET c_hotel=round(3.0/111, 4) WHERE [State of Hotel] = "Tripura";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(5.0/111, 4) WHERE [State of Hotel] = "Tamil Nadu";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(2.0/111, 4) WHERE [State of Hotel] = "Haryana";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(4.0/111, 4) WHERE [State of Hotel] = "Punjab";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(1.0/111, 4) WHERE [State of Hotel] = "Uttarakhand";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(14.0/111, 4) WHERE [State of Hotel] = "Maharashtra";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(5.0/111, 4) WHERE [State of Hotel] = "West Bengal";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(6.0/111, 4) WHERE [State of Hotel] = "Karnataka";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(4.0/111, 4) WHERE [State of Hotel] = "Rajasthan";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(8.0/111, 4) WHERE [State of Hotel] = "Delhi";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(8.0/111, 4) WHERE [State of Hotel] = "Assam";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(1.0/111, 4) WHERE [State of Hotel] = "Goa";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(2.0/111, 4) WHERE [State of Hotel] = "Andhra Pradesh";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(20.0/111, 4) WHERE [State of Hotel] = "Jammu and Kashmir";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(7.0/111, 4) WHERE [State of Hotel] = "Uttar Pradesh";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(3.0/111, 4) WHERE [State of Hotel] = "Bihar";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(2.0/111, 4) WHERE [State of Hotel] = "Gujrat";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(3.0/111, 4) WHERE [State of Hotel] = "Hyderabad";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(2.0/111, 4) WHERE [State of Hotel] = "Manipur";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(8.0/111, 4) WHERE [State of Hotel] = "Chhattishgarh";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(2.0/111, 4) WHERE [State of Hotel] = "Jharkhand";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(1.0/111, 4) WHERE [State of Hotel] = "Madhya Pradesh";''')
        c.execute('''UPDATE Mediator SET c_hotel=round(0.0/111, 4) WHERE [c_hotel] IS NULL;''')
        c.execute('''UPDATE Mediator SET Reason=Reason || " ," || "The Hotel booked is in " || [State of Hotel] WHERE [c_hotel]!=0.0;''')

        #Duplicate Address and Contact no.:
        c.execute('''CREATE TABLE M AS SELECT Mediator.[Address(House No, Street)],Mediator.[City of Residence], COUNT(*) c FROM Mediator GROUP BY Mediator.[Address(House No, Street)],Mediator.[City of Residence] HAVING c > 1;''')
        c.execute('''CREATE TABLE Dup_Address AS SELECT * FROM Mediator h JOIN M ON (h.[Address(House No, Street)]= M.[Address(House No, Street)] AND h.[City of Residence]=M.[City of Residence]);''')
        c.execute('''CREATE TABLE Dup_Contact AS SELECT * FROM Mediator WHERE Mediator.[Contact no] IN (SELECT [Contact no] FROM (SELECT Mediator.[Contact no], COUNT(*) c FROM Mediator GROUP BY Mediator.[Contact no] HAVING c > 1));''')
        c.execute('''DROP TABLE M;''')
        c.execute('''UPDATE Mediator SET c_dup_cont_add=round(6.0/6, 4) WHERE (Mediator.[Address(House No, Street)], Mediator.[City of Residence]) IN (SELECT Dup_Address.[Address(House No, Street)], Dup_Address.[City of Residence] FROM Dup_Address) OR Mediator.[Contact no] IN (SELECT Dup_Contact.[Contact no] FROM Dup_Contact);''')
        c.execute('''UPDATE Mediator SET c_dup_cont_add=round(0.0/6, 4) WHERE c_dup_cont_add IS NULL;''')
        c.execute('''UPDATE Mediator SET Reason=Reason || ", Person's Address is a duplicate, " WHERE (Mediator.[Address(House No, Street)], Mediator.[City of Residence]) IN (SELECT Dup_Address.[Address(House No, Street)], Dup_Address.[City of Residence] FROM Dup_Address) OR Mediator.[Contact no] IN (SELECT Dup_Contact.[Contact no] FROM Dup_Contact);''')
        c.execute('''UPDATE Mediator SET Reason=Reason ||", Person's Contact number is a duplicate, " WHERE Mediator.[Contact no] IN (SELECT [Contact no] FROM (SELECT Mediator.[Contact no], COUNT(*) c FROM Mediator GROUP BY Mediator.[Contact no] HAVING c > 1));''')

        #Calculating score:
        c.execute('''UPDATE Mediator SET score=round(100 *((0.4*Mediator.[c_residence])+(0.5*Mediator.[c_hotel])+(0.1*Mediator.[c_dup_cont_add])), 4);''')
        c.execute('''CREATE TABLE Dup_Aadhar AS SELECT * FROM Mediator WHERE [Aadhar no] IN (SELECT [Aadhar no] FROM (SELECT Mediator.[Aadhar no], COUNT(*) c FROM Mediator GROUP BY Mediator.[Aadhar no] HAVING c > 1));''')
        c.execute('''CREATE TABLE Reported AS SELECT a."Customer Name", a."Aadhar no", a."Contact no", a."Address(House No, Street)", a."City of Residence", a."State of Residence", a."City of Hotel", a."State of Hotel", a."Stay Date", a."score", a."Reason" FROM Dup_Aadhar  AS a JOIN Dup_Aadhar  AS b ON (a.[Aadhar no]=b.[Aadhar no] AND ((SELECT (julianday(a.[Stay Date]) - julianday(b.[Stay Date]))>30) OR (SELECT (julianday(b.[Stay Date]) - julianday(a.[Stay Date]))>30)) );''')
        c.execute('''DROP TABLE Dup_Aadhar;''')
        c.execute('''DROP TABLE Dup_Address;''')
        c.execute('''DROP TABLE Dup_Contact;''')

        conn.commit()
        
conn.close()    

Answer 1

There are a few things you can try

1. Make sure that your Python script is located in the correct directory and that the file path in the spawn function is correct.

2. Check the console logs for any errors or messages that might give a clue about what is going wrong.

3. In the Node.js server, you are setting a variable dataToSend but it is never used or defined. Try removing this variable to see if it is causing any issues.

4. Make sure that the Python script is actually creating the database. You can do this by running the script directly from the command line and checking if the database is created.

5. In the process.on('close') event handler, you are not sending any data back to the browser. This could be the reason why you are not seeing any output in the React application. Try sending the data back to the browser using res.send(), as you do in the process.stdout.on('data') event handler.