Python Flask Form - html Selectbox returning 'None' as the selected item
Question
I am creating a website server program with Flask and Python, I am relatively new to Flask. I have created a html form with a Select tag (drop down menu, single select). You can see the code below.
selectmenu.html
<!doctype html>
<html>
<body>
<form id="form" method="POST" class="selectform">
<select method="GET" size=5>
{% for x in options %}
<option value="{{x}}" SELECTED>{{x}}</option>
{% endfor %}
</select>
<input type="submit" name="go"></input>
</form>
</body>
</html>
The Python code for Flask: app.py
@app.route('/selectmenu',methods=(['GET','POST']))
def selmenu():
optionfiles = os.listdir('options')
form = selectform()
if request.method == 'POST':
selectedoption = form.selectedoption.data
print(selectedoption)
return redirect('/')
return render_template('selectmenu.html',options=optionfiles,form=form)
And finally the Python WTForms classes code forms.py :
class selectform(FlaskForm):
optionfiles = os.listdir('userdata')
print(optionfiles)
selectedoption = SelectField('selectdropdown', choices=optionfiles,validators=[DataRequired()])
submitbutton = SubmitField('submit',validators=[DataRequired()])
But when the program called form.selectoption.data it returns None every time.
I have tried many tutorials, and Stackoverflow answers, but still can't get data from the form that isn't None .
NOTE: As you can tell I have uploaded snippets only of the code, as the actual files are all a lot larger, If you need any other bits of the code. e:g, the imports, then please ask, but I am pretty sure the error isn't the imports. for example! Otherwise I would receive an ImportError.
Thank you in advance for your help!
2 answers
solution1
0 2020-08-02 11:46:20
It seems that you are using Flask-WTF (FlaskForm) but the way you write the html part is not compliant with it. To confirm you can replace selectmenu.html by:
<!doctype html>
<html>
<body>
<form method="POST">
{{ form.selectedoption() }}
{{ form.csrf_token }}
{{ form.submitbutton(class_='btn btn-primary') }}
</form>
</body>
</html>
If it is the case you might have a look at https://flask-wtf.readthedocs.io/en/stable/quickstart.html and https://flask.palletsprojects.com/en/1.1.x/patterns/wtforms/#forms-in-templates (for the easy template).
(And return render_template('selectmenu.html',options=optionfiles,form=form) can be replaced by return render_template('selectmenu.html',form=form) )
solution2
0 2020-08-02 12:10:25
After finding this Stackoverflow post I found the answer.
I needed to use give the <select> tag a name, like this: name="optionsbox" in the html file. Then do request.form.get("optionsbox") in the app.py file, instead of form.selectedoption.data . No changes needed in the forms.py file.
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