flask View function mapping is overwriting an existing endpoint function: type

Question

I recently purchased RealPython to learn about Python and web development. However, I have ran into a road block that I think is a Python configuration issue on my machine. Any help would be much obliged.

So I have a Flask document called app.py similar to RealPython's github app.py

# --- Flask Hello World ---#

# import the Flask class from the flask module
from flask import Flask

# create the application object
app = Flask(__name__)

# use decorators to link the function to a url
@app.route("/")
@app.route("/hello")

# define the view using a function, which returns a string
def hello_world():
    return "Hello, World!"

# dynamic route
@app.route("/test/<search_query>")
def search(search_query):
    return search_query

# dynamic route with an int type
@app.route("/integer/<int:value>")
def type(value):
    print value + 1
    return "correct"

# dynamic route with an float type
@app.route("/float/<float:value>")
def type(value):
    print value + 1
    return "correct"

# dynamic route that accepts slashes
@app.route("/path/<path:value>")
def type(value):
    print value
    return "correct"



# start the development server using the run() method
if __name__ == "__main__":
    app.run()

I unfortunately receive this error when trying to run the app:

machine:flask-hello-world machine$ source env/bin/activate
(env)machine:flask-hello-world machine$ python app.py
Traceback (most recent call last):
  File "app.py", line 29, in <module>
    @app.route("/float/<float:value>")
  File "/Volumes/disk2/Home/Library/RealPython/flask-hello-world/env/lib/python2.7/site-packages/flask/app.py", line 1013, in decorator
    self.add_url_rule(rule, endpoint, f, **options)
  File "/Volumes/disk2/Home/Library/RealPython/flask-hello-world/env/lib/python2.7/site-packages/flask/app.py", line 62, in wrapper_func
    return f(self, *args, **kwargs)
  File "/Volumes/disk2/Home/Library/RealPython/flask-hello-world/env/lib/python2.7/site-packages/flask/app.py", line 984, in add_url_rule
    'existing endpoint function: %s' % endpoint)
AssertionError: View function mapping is overwriting an existing endpoint function: type

Pip freeze gives these as requirements for virtualenv env. Python 2.7 is what is installed.

Flask==0.10.1
Jinja2==2.7.3
MarkupSafe==0.23
Werkzeug==0.9.6
itsdangerous==0.24
wsgiref==0.1.2

---

The only way I've been able to get the code to run is by changing def type. One should not have to do this though...

# dynamic route with an int type
@app.route("/integer/<int:value>")
def type(value):
    print value + 1
    return "correct"

# dynamic route with an float type
# change to type1 so dev server will spool up
@app.route("/float/<float:value>")
def type1(value):
    print value + 1
    return "correct"

# dynamic route that accepts slashes
# change to type2 so dev server will spool up
@app.route("/path/<path:value>")
def type2(value):
    print value
    return "correct"

---

Solution

Answer 1

So, you figured out the solution: It's a namespace issue. You have three functions that are conflicting against one another - def type. When you renamed them using different names, this fixed the issue.

I am the author of Real Python, by the way. Correcting now.

Cheers!

Answer 2

three of your methods have the same name. The wrappers use the name of the method to do their mapping