Flask. Processing a form on another page. TypeError: The view function did not return a valid response - python-3.x

Question

Good day!
I'm new to Python and Flask
I am trying to render a form on another page when I apply this construction :
#app.route('/tools', methods=['POST', 'GET'])
def tools():
"""Form Create Users"""
createadduser_form = ToolsAddUser()
return render_template("tools.html", title='Admin Tools', **locals())
#app.route('/createuser', methods=["GET", "POST"])
def createuser():
if request.method == 'POST':
adduser_clientid = request.form["adduser_clientid"]
adduser_value = request.form["adduser_value"]
create(adduser_clientid, adduser_value)
return redirect("tools")
But in the event that I use another one with field validation, it does not work:
#app.route('/tools', methods=['POST', 'GET'])
def tools():
createadduser_form = ToolsAddUser()
return render_template("tools.html", title='Admin Tools', **locals())
#app.route('/createuser', methods=["GET", "POST"])
def createuser():
createadduser_form = ToolsAddUser()
if createadduser_form.validate_on_submit():
adduser_clientid = request.form["adduser_clientid"]
adduser_value = request.form["adduser_value"]
create(adduser_clientid, adduser_value)
return redirect("tools")
I understand the problem here:
if createadduser_form.validate_on_submit():
if request.method == 'POST':
In the first option, when you click on the button, the script works as needed (the script is launched powershell, so do not pay attention to the names of the variables, this is a test)))) everything works well
In the second option, it shows an error:
I can't understand what the problem is, little experience. I would be very grateful for your help.
http://127.0.0.1:5000/createuser
TypeError
TypeError: The view function did not return a valid response. The function either returned None or ended without a return statement.
Traceback (most recent call last)
File "E:\Project\web\venv\lib\site-packages\flask\app.py", line 2464, in __call__
return self.wsgi_app(environ, start_response)
File "E:\Project\web\venv\lib\site-packages\flask\app.py", line 2450, in wsgi_app
response = self.handle_exception(e)
File "E:\Project\web\venv\lib\site-packages\flask\app.py", line 1867, in handle_exception
reraise(exc_type, exc_value, tb)
File "E:\Project\web\venv\lib\site-packages\flask\_compat.py", line 39, in reraise
raise value
File "E:\Project\web\venv\lib\site-packages\flask\app.py", line 2447, in wsgi_app
response = self.full_dispatch_request()
File "E:\Project\web\venv\lib\site-packages\flask\app.py", line 1953, in full_dispatch_request
return self.finalize_request(rv)
File "E:\Project\web\venv\lib\site-packages\flask\app.py", line 1968, in finalize_request
response = self.make_response(rv)
File "E:\Project\web\venv\lib\site-packages\flask\app.py", line 2098, in make_response
"The view function did not return a valid response. The"
TypeError: The view function did not return a valid response. The function either returned None or ended without a return statement.
Below, just in case, the form itself...
class ToolsAddUser(FlaskForm):
adduser_clientid = StringField('Client ID',
validators=[DataRequired()],
render_kw={'class': 'form-control',
'placeholder': 'Client ID'})
adduser_value = StringField('Value',
validators=[DataRequired()],
render_kw={'class': 'form-control',
'placeholder': 'Value'})
submitbuttonuser = SubmitField('Submit',
render_kw={'class': 'btn btn-dark'})
I apologize for the inaccuracies in the wording
<form action="/createuser" method="post">
 <div class="form-group form shadow">
 <label for="">
 <h5>Add User</h5>
 </label>
 {{ createadduser_form.adduser_clientid }}<br>
 {{ createadduser_form.adduser_value }}<br>
 <input type="text" class="form-control" placeholder="Example input" style="visibility: hidden;"><br>
 {{ createadduser_form.submitbuttonuser }}
 </div>
</form>

Answer 1

You're not returning a response when you navigate to /createuser, which will be a GET. You are only returning a response within if createadduser_form.validate_on_submit():, which will only handle the POST call.
I assume you'll be wanting to render the form you've created, like:
return render_template("createuser.html")

Answer 2

Thank you all who paid attention to this topic, I have solved my problem. The thing is that I didn't add the cars page to the html
It turns out that the CSRF check did not pass my request further than the page
{{ {{ create add user_form.hidden_tag () }}
For this check, it is required
if create add user_form.validate_on_submit():
Week, week, week