I have created a website using flask that takes in a string, creates a url based off the string, parses the url and then feeds it back into the website. I created a function to do so and it works perfectly. However when I implement it within my flask program it started throwing a runtime error that states:
An application error occurred on the server. The current custom error settings for this application prevent the details of the application error from being viewed remotely (for security reasons). It could, however, be viewed by browsers running on the local server machine.
Details:To enable the details of this specific error message to be viewable on remote machines, please create a customErrors tag within a "web.config" configuration file located in the root directory of the current web application. This customErrors tag should then have its "mode" attribute set to "Off".
I am not familiar with creating a web.config or how to implement this within my flask program. Any help would be appreciated.
Code:
Function that works when ran on it's own:
def parse_wotc():
set_list = []
# Manually enter in value for test
card_url = 'http://gatherer.wizards.com/Pages/Card/Details.aspx?name=' +
'mountain' # (replace mountain) card_name.replace(' ', '+')
soup = BeautifulSoup(requests.get(card_url).text, 'html.parser')
for image in soup.find_all('img'):
if image.get('title') is not None:
set_list.append(image.get('title'))
print(set_list)
return set_list
webapp code:
#app.route('/', methods=['GET', 'POST'])
def index():
card_name = None
card_url = '/static/images/card_back.jpg'
if request.form.get('random_button'):
card_url, card_name = random_card_image(list_card_names)
# When function ran here it give the error
parse_wotc(card_name)
def random_card_image(list_card_names):
"""This function will pull a random card name from the provided list and
return to main program"""
card_name = random.choice(list_card_names)
card_url = 'http://gatherer.wizards.com/Handlers/Image.ashx?name=' +
card_name.replace(' ', '+').lower() + \
'&type=card'
return card_url, card_name
It took a couple of hours to determine what the issue was, but it is working now. The issue is that I made a text file that had a list of card names that I was pulling from to create a random selection - the text file however included a trailing \n on each entry. Therefore it was creating a url with \n in it which was unnoticeable at the time and causing an error. I used rsplit() when creating the name list to remove the trailing \n and now it works perfectly.
Related
I'm a computer science student. Recently we were tasked to develop a static HTTP server from scratch without using any HTTP modules, solely depending on socket programming. So this means that I had to write all the logic for HTTP message parsing, extracting headers, parsing URLs, etc.
However, I'm stuck with some confusion. As I'm somewhat experienced in web development before, I'm used to using URLs in places like anchor tags like this "/about", and "/articles/article-1".However, I've seen people sometimes people to relative paths according to their folder structure like this. "./about.html", "../contact.html".This always seemed to be a bad idea to me. However, I realized that even though in my code I'm not supporting these kinds of URLs explicitly, it seems to work anyhow.
Following is the python code I'm using to get the path from the HTTP message and then get the corresponding path in the file system.
def get_http_url(self, raw_request_headers: list[str]):
"""
Method to get HTTP url by parsing request headers
"""
if len(raw_request_headers) > 0:
method_and_path_header = raw_request_headers[0]
method_and_path_header_segments = method_and_path_header.split(" ")
if len(method_and_path_header_segments) >= 2:
"""
example: GET / HTTP/1.1 => ['GET', '/', 'HTTP/1.1] => '/'
"""
url = method_and_path_header_segments[1]
return url
return False
def get_resource_path_for_url(self, path: str | Literal[False]):
"""
Method to get the resource path based on url
"""
if not path:
return False
else:
if path.endswith('/'):
# Removing trailing '/' to make it easy to parse the url
path = path[0:-1]
# Split to see if the url also includes the file extension
parts = path.split('.')
if path == '':
# if the requested path is "/"
path_to_resource = os.path.join(
os.getcwd(), "htdocs", "index.html")
else:
# Assumes the user entered a valid url with resources file extension as well, ex: http://localhost:2728/pages/about.html
if len(parts) > 1:
path_to_resource = os.path.join(
os.getcwd(), "htdocs", path[1:]) # Get the abslute path with the existing file extension
else:
# Assumes user requested a url without an extension and as such is hoping for a html response
path_to_resource = os.path.join(
os.getcwd(), "htdocs", f"{path[1:]}.html") # Get the absolute path to the corresponding html file
return path_to_resource
So in my code, I'm not explicitly adding any logic to handle that kind of relative path. But somehow, when I use things like ../about.html in my test HTML files, it somehow works?
Is this the expected behavior? As of now (I would like to know where this behavior is implemented), I'm on Windows if that matters. And if this is expected, can I depend on this behavior and conclude that it's safe to refer to HTML files and other assets with relative paths like this on my web server?
Thanks in advance for any help, and I apologize if my question is not clear or well-formed.
#app.route("/admin/3")
def admin3_p():
return render_template("input_test.html")
#app.route("/admin/3", methods=['POST'])
def student_name():
with app.test_request_context('/admin/3', data='student'):
variable = request.form.get('student', list(''))
return variable
# Connect to CSV
def csv_func():
variable = student_name()
csv_f = "names.csv"
titles = ["Event", "Student", "Grade"]
students = [["Ev", "St", "Gr"], [variable]]
with open(csv_f, 'w') as csvfile:
csvwriter = csv.writer(csvfile)
csvwriter.writerow(titles)
csvwriter.writerows(students)
with open(csv_f, 'r') as csvfile:
csvreader = csv.reader(csvfile)
titles = next(csvreader)
for student in csvreader:
students.append(students)
print('Fields: ' + ', '.join(title for title in titles))
print(students)
csv_func()
I am trying to make a website with Flask. Th csv_func method is supposed to take the input from the html and print it to a csv file.
It returns "TypeError: The view function did not return a valid response. The return type must be a string, dict, tuple, Response instance, or WSGI callable, but it was a list" When it runs
Technically the error is because function with a route decorator is considered 'a view' and is supposed to return a page, yet yours student_name returns a tuple (of student names)
Yet I have to tell you that you got it wrong idea of web app syntax and structure. Your flow of control is opposite from what is should be. You should initiate model and csv changes from controller (student_name function), and you are doing it vise versa, by calling student_name from . The main code usually just start web app with something like
app.run(host='0.0.0.0', port=81)
So you should restructure you code in a so student_name function invokes csv changing function.
I guess you think that web app form is akin to input command in python, yet a web app is very different from python console input. The main difference is that website normally offer several different pages, and user is free to land on any page he likes. So normal webserver just wait for user landing to one or another page or sending one or another form. Thus the structure of web app is a set of pages, routes and controllers for that pages, and main code just starts the flask server. Go throw some introductory flask tutorial if it is still
unclear. E.g. https://flask.palletsprojects.com/en/1.1.x/quickstart/
Most web apps follow UI design pattern called Model-View-Controller, where user actions, such as opening a webpage on a specific web address or filling a form first hit some controlling code, which the initiates some changes in the model (data).
Get rid of the app.route(...) decorator above def student_name():.
I am building a Flask webapp and it uses the OpenBabel API (chemistry toolkit) to generate some files for me. When I call this particular function it seems to work fine and generate the files in the directory that I want. However, once it gets back to Flask it crashes and Flask does not render the html template, instead redirecting me to This page isn’t working 127.0.0.1 didn’t send any data. I found that when removing the code in the function it works normally. So it's likely a problem with OpenBabel. The Openbabel function does not ouput any errors itself and seemingly even returns at the end, based on debugging.
I have tried many things from other SO answers, including changing my host to 0.0.0.0, adding threaded=True and some other solutions. All to no avail. I tried debugging it for a long time, but now I am lost because I have tried everything I know. All I could get was a SystemExit exception from Flask. Sometimes it was able to run the print statement following it, but more often it crashes immediately. I have no clue where the problem may lie. Appreciate any help I can get. A sample of the code (shortened it a bit):
#app.route("/", methods=["POST", "GET"])
def form_handler():
if request.method == "POST":
smiles = request.form["smiles_molecule"]
pdb_file = request.files["pdb_molecule"]
no_conformers = int(request.form["no_conformers"])
scoring = request.form["score"]
if smiles:
pattern = re.compile('[^A-Za-z0-9]+')
smiles_no_special_chars = re.sub(pattern, "", smiles)
mol_path = os.path.join(app.config["MOLECULE_UPLOADS"], smiles_no_special_chars[0:10])
if os.path.exists(mol_path):
shutil.rmtree(mol_path)
os.mkdir(mol_path)
os.chdir(mol_path)
x = conf_gen.gen_and_write_confs(smiles, no_conformers, scoring) #<- breaks down here
print(x)
return render_template("index.html", mole=smiles_no_special_chars[0:10])
The function that is called:
def gen_and_write_confs(molecule, no_confs, scoring):
"""Generate and write the conformers to PDB. Takes mol, number of conformers and
scoring method: RCS, MECS and ECS: OBRMSDConformerScore,
OBMinimizingEnergyConformerScore and OBEnergyConformerScore. See OpenBabel docs."""
mole = pybel.readstring("can", molecule)
mole.addh()
mole.make3D()
mole = mole.OBMol
mole.SetChainsPerceived(True)
cs_obj = ob.OBConformerSearch()
cs_obj.Setup(mole, no_confs, 5, 5, 25)
if scoring == "RCS":
score = ob.OBRMSDConformerScore()
elif scoring == "MECS":
score = ob.OBMinimizingEnergyConformerScore()
else:
score = ob.OBEnergyConformerScore()
cs_obj.SetScore(score)
cs_obj.Search()
cs_obj.GetConformers(mole)
mole.DeleteNonPolarHydrogens()
return "Test"
If needed I can upload the project on Github. It does require installing a few dependencies and I am using conda for that right now, but I could make it available through pip too since OpenBabel is available in pip.
Ps: no single error message is shown after it crashes
When I run the server.py which is hosted on 127.0.0.1:5000 it generates the list of articles
#app.route("/")
def articles():
"""Show a list of article titles"""
return render_template('articles.html', my_list= Alist)
The code above generates the list of articles and is running properly when I run 127.0.0.1:5000, the list is displayed.
#app.route("/article/<topic>/<filename>")
def article(topic,filename):
"""
Show an article with relative path filename. Assumes the BBC structure of
topic/filename.txt so our URLs follow that.
"""
for art in articles_table:
if art[0]== "%s/%s" %(topic, filename):
title_str = art[1]
text_list = art[2].split('\n')
text_list = [t.lower() for t in text_list if len(t) >= 1]
rec = recommended(art[0], articles_table, 5)
break
return render_template('article.html', title=title_str, text=text_list,
fiveA= rec)
However, whenever I click on any of the articles it redirects to http://127.0.0.1:5000/article/data/bbc/business/003.txt
and generates error 404 but the file is present at a particular path in the local directory
I believe the error is in the 2nd code snippet.
I'm a beginner to flask so I'm really confused as to what to do. Any help will be appreciated
If I understand correctly you are trying to catch the topic and the filename in the route. The problem is the URL you're trying to access doesn't match the route you have defined.
You have 2 options:
Change the link so the URL is http://127.0.0.1:5000/article/business/003.txt. By doing this you'll be able to keep the same route you currently have #app.route("/article/<topic>/<filename>"). Here topicwill have the value of "business" and filename will have the value of "003.txt".
Or you can leave the link so the URL stays the same (http://127.0.0.1:5000/article/data/bbc/business/003.txt) and you can change your route to look like this: #app.route("/article/data/bbc/<topic>/<filename>"). Again topic will have the value of "business" and filename will have the value of "003.txt".
You can find more information about routes here
I've been meaning to log all the users that visit the site to a file.
Using Flask for the backend.
I have not been able to get python to write to the file. Tried keeping exception handling to catch any errors that might be generated while writing. No exceptions are being raised.
Here is the part of the blueprint that should write to file.
from .UserDataCache import UserDataCache
udc = UserDataCache()
#main.route('/')
def index():
s = Suggestion.query.all()
udc.writeUsertoFile()
return render_template('suggestions.html', suggestions = s)
Here is the UserDataCache class:
from flask import request
from datetime import datetime
class UserDataCache():
def __init__(self):
pass
def writeUsertoFile(self):
try:
with open("userData.txt","a") as f:
f.write(str(datetime.now()) + " " + request.remote_addr + " " + request.url + " " + request.headers.get('User-Agent') + "\n")
except IOError,e:
print e
return
I recommend using an absolute path and verifying the permissions on that file. Something like /tmp/UserData.txt or another absolute path should work. The web server's user is what needs the permission to write to the file (www-data if you're using apache2 with Ubuntu, or check your web server's conf file to verify).
As far as why you're not seeing the exception you're catching, I see you're using print. If you're calling the app using a web browser, you'll need to send the error to something else, like a log file or flash it to the browser, or raise an error so it gets logged in the web server error log.
Is your python file name begins with uppercase? If so, try to modify it into lowercase.
I just came into the same problem and copied the exactly same code into two .py file. The only difference is their file name, one being 'Flask_test.py' and another being 'flask_for_test.py'. It's weird that 'Flask_test.py' works just fine except it cannot write into any file and 'flask_for_test.py' works perfectly.
I don't know whether the format of the file name has an effect on the function of python but using lowercase file name works for me.
By the way, all other solutions I found didn't work.