Question

I’m trying to pull the value of a variable from inside a function in Python, but I’m having a bit of trouble.

uri = None
clientHostname = None
clientIP = None
...
# Handles requests
class DataHandler(BaseHTTPServer.BaseHTTPRequestHandler):
    def do_HEAD(dServe):
        dServe.send_response(200)
        dServe.send_header("connection-type", "text/html")
        dServe.end_headers()
    def do_GET(dServe):
        global uri
        dServe.send_response(200)
        dServe.send_header("connection-type", "text/html")
        uri = dServe.path
        dServe.end_headers()
        clientHostname = dServe.address_string()
        clientIP = dServe.connection.getsockname()[0]
    print(uri)
    print(clientHostname)
    print(clientIP)

When I try and execute this, they only return the value ‘None’. Any pointers? This is my first endeavor into Python(2.7) and I’m still climbing the bell curve on it.

My fulls script is currently:

import time
import BaseHTTPServer
import StringIO
import csv
import sqlite3 as sql
import SimpleHTTPServer
import SocketServer
import multiprocessing
import os


# Initial Variables
appsTable = "Apps"
groupsTable = "Groups"
hostName = 'localhost'
dataPort = 277
filePort = 438
dbFile = "Get-App.db"
uri = None
    clientHostname = None
    clientIP = None
if os.name == "nt":
    dbPath = "Dependencies\sqlite3"
else:
    dbPath = "Dependencies/sqlite3"

# Checks for DB and creates if not found
if os.path.exists(dbFile):
    print("Database found!")
else:
    print("Creating New Database...")
    os.system("echo .tables | " + dbPath + " " + dbFile)
    sqlConnect = None
    try:
        sqlConnect = sql.connect(dbFile)
        sqlCursor = sqlConnect.cursor()
        sqlCursor.execute('CREATE TABLE ' + appsTable + '(ID INTEGER PRIMARY KEY ASC, Name TEXT, InstallGroup TEXT, Version TEXT, Arch TEXT, Executable TEXT, Path TEXT, Command TEXT, Latest BOOL, Enabled BOOL)')
        sqlCursor.execute('CREATE TABLE ' + groupsTable + '(ID INTEGER PRIMARY KEY ASC, Name TEXT, AppList TEXT, Version TEXT, Arch TEXT, Latest BOOL, Enabled BOOL)')
    finally:
        if sqlConnect:
            sqlConnect.close

# Serves files
def file_serve():
    if not os.path.exists(dbFile):
        os.makedirs(appsTable)
    os.chdir(appsTable)
    FileHandler = SimpleHTTPServer.SimpleHTTPRequestHandler
    fileServer = SocketServer.TCPServer(("", filePort), FileHandler)
    fileServer.serve_forever()

# Handles requests
class DataHandler(BaseHTTPServer.BaseHTTPRequestHandler):
    def do_HEAD(dServe):
        dServe.send_response(200)
        dServe.send_header("connection-type", "text/html")
        dServe.end_headers()
    def do_GET(dServe):
        global uri
        dServe.send_response(200)
        dServe.send_header("connection-type", "text/html")
        uri = dServe.path
        dServe.end_headers()
        clientHostname = dServe.address_string()
        clientIP = dServe.connection.getsockname()[0]
        dServe.wfile.write(uri)
    print(uri)
    print(clientHostname)
    print(clientIP)


    # This is what's written to the page:
    uriPar = csv.reader(uri, delimiter='?')
    uriEnt = csv.reader(uriPar[0], delimiter='/')
    sqlConnect = sql.connect(dbFile)
    for entity in uriEnt:
        with sqlConnect:    
            sqlCursor = sqlConnect.cursor()
                if entity[1] == "app":
                    if len(entity) == 3:
                        print clientHostname + " made request for app " + entity[2]
                        sqlCursor.execute("SELECT Executable,Path,Command FROM " + appsTable + " WHERE Latest='true' AND Enabled='true' AND Name='" + entity[2] + "'")
                    else:
                        print clientHostname + " made request for app " + entity[2] + ", specifically version " + entity[3]
                        sqlCursor.execute("SELECT Executable,Path,Command FROM " + appsTable + " WHERE Enabled='true' AND Version='" + entity[3] + "' AND Name='" + entity[2] + "'")
                elif entity[1] == "group":
                    if len(entity) == 3:
                        print clientHostname + " made request for group " + entity[2]
                        sqlCursor.execute("SELECT AppList FROM " + groupsTable + " WHERE Latest='true' AND Enabled='true' AND Name='" + entity[2] + "'")
                    else:
                        print clientHostname + " made request for group " + entity[2] + ", specifically version " + entity[3]
                        sqlCursor.execute("SELECT AppList FROM " + groupsTable + " WHERE Enabled='true' AND Version='" + entity[3] + "' AND Name='" + entity[2] + "'")
    rows = sqlCursor.fetchall()
    for place in rows:
        for position in place:
            dServe.wfile.write(position)
            dServe.wfile.write(",")

# Serves http
if __name__ == '__main__':
    dataServer_class = BaseHTTPServer.HTTPServer
    dataServer = dataServer_class((hostName, dataPort), DataHandler)
    print time.asctime(), "Data Service Starts - %s:%s" % (hostName, dataPort)
    print time.asctime(), "File Service Starts - %s:%s" % (hostName, filePort)
    try:
    fileServerThread = multiprocessing.Process(target=file_serve) 
    fileServerThread.start()  # Starts File Server
        dataServer.serve_forever()  # Starts HTTP Server
    except KeyboardInterrupt:
        pass
    dataServer.server_close()
    fileServer.server_close()
    print time.asctime(), "Server Stops - %s:%s" % (hostName, dataPort)

Answer 1

Fist of all, all the print statements in your code are executed at the time the class definition is loaded, probably not what you really want.

Second, if this is complete code, you never ever construct and start your HTTP server instance. You need a code more or less like this, it instantiates and starts the server object:

if __name__ == '__main__':
    httpd = BaseHTTPServer.HTTPServer((HOST_NAME, PORT_NUMBER), DataHandler)
    try:
        httpd.serve_forever()
    except KeyboardInterrupt:
        pass
    httpd.server_close()

Also, using global variables this way is not a good idea – for example, what if your server accepts many connections at the same time?

If you’re new to Python, I suggest you start playing with existing, working code, e.g. this sample.

Edit: It seems you have parts of the code incorrectly indented. Look at the following example:

class Test(object):

    def run(self):
        print 1
    print 2

# By this time, '2' is already printed!
print 3
t = Test()
t.run()

It prints out:

2
3
1

The same is going on in your code – print statements and the code following it is indented by 4 spaces, so it will run when the class is being parsed (well, not exactly, simplifying a bit).