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What i want to do is just display the firstevent from one API. The variable is called “firstevent” and the value should display on the webpage. But firstevent is inside a def, so i change it into a global variable and hope it can be used across different functions. But it shows “NameError: global name 'firstevent' is not defined”. This is what I am doing:
define a global variable
global firstevent send this variable a random value, it supposed to be events['items'][1]['end']
firstevent = 1 displaying firstevent’s value on website.
@app.route("/") def index(): return 'User %s' % firstevent I am not sure what’s happening now, maybe it’s a scope issue? I have check many answers online but still cannot find the solution.
Here are the details(not the whole code)
import os # Retrieve Flask, our framework # request module gives access to incoming request data import argparse import httplib2 import os import sys import json from flask import Flask, request from apiclient import discovery from oauth2client import file from oauth2client import client from oauth2client import tools from apiclient.discovery import build from oauth2client.client import OAuth2WebServerFlow import httplib2 global firstevent app = Flask(__name__) def main(argv): # Parse the command-line flags. flags = parser.parse_args(argv[1:]) # If the credentials don't exist or are invalid run through the native client # flow. The Storage object will ensure that if successful the good # credentials will get written back to the file. storage = file.Storage('sample.dat') credentials = storage.get() if credentials is None or credentials.invalid: credentials = tools.run_flow(FLOW, storage, flags) # Create an httplib2.Http object to handle our HTTP requests and authorize it # with our good Credentials. http = httplib2.Http() http = credentials.authorize(http) # Construct the service object for the interacting with the Calendar API. calendar = discovery.build('calendar', 'v3', http=http) created_event = calendar.events().quickAdd(calendarId='[email protected]', text='Appointment at Somewhere on June 3rd 10am-10:25am').execute() events = calendar.events().list(calendarId='[email protected]').execute() #firstevent = events['items'][1]['end'] firstevent = 1 #print events['items'][1]['end'] # Main Page Route @app.route("/") def index(): return 'User %s' % firstevent # Second Page Route @app.route("/page2") def page2(): return """<html><body> <h2>Welcome to page 2</h2> <p>This is just amazing!</p> </body></html>""" # start the webserver if __name__ == "__main__": app.debug = True app.run() 
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To share data that is valid for one request only from one function to another, a global variable is not good enough because it would break in threaded environments. Flask provides you with a special object that ensures it is only valid for the active request and that will return different values for each request.
You can't use global variables to hold this sort of data. Not only is it not thread safe, it's not process safe, and WSGI servers in production spawn multiple processes. Not only would your counts be wrong if you were using threads to handle requests, they would also vary depending on which process handled the request.
If a global and a local variable with the same name are in scope, which means accessible, at the same time, your code can access only the local variable.
In C, multiple global variables are "merged" into one. So you have indeed just one global variable, declared multiple times.
Yep, it's a scope problem. In the beginning of your main() function, add this:
global firstevent That should done it. Any variable that is not defined inside a function, is a global. You can access it straightly from any function. However, to modify the variable you'll need to write global var in your function.
Example
This creates a local variable "firstevent" on the function:
firstevent = 0 def modify(): firstevent = 1 And this modifies the global variable 'firstevent'
firstevent = 0 def modify(): global firstevent firstevent = 1 If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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