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Checkbox WTForms Example (in Flask)
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<form method="post">
{{ form.hidden_tag() }}
{{ form.example }}
<button type="submit">Submit</button>
</form>
</body>
</html>
from flask import Flask, render_template
from flask_wtf import FlaskForm
from wtforms import widgets, SelectMultipleField
SECRET_KEY = 'development'
app = Flask(__name__)
app.config.from_object(__name__)
class MultiCheckboxField(SelectMultipleField):
widget = widgets.ListWidget(prefix_label=False)
option_widget = widgets.CheckboxInput()
class SimpleForm(FlaskForm):
string_of_files = ['one\r\ntwo\r\nthree\r\n']
list_of_files = string_of_files[0].split()
# create a list of value/description tuples
files = [(x, x) for x in list_of_files]
example = MultiCheckboxField('Label', choices=files)
@app.route('/',methods=['post','get'])
def hello_world():
form = SimpleForm()
if form.validate_on_submit():
print(form.example.data)
return render_template("success.html", data=form.example.data)
else:
print("Validation Failed")
print(form.errors)
return render_template('example.html',form=form)
if __name__ == '__main__':
app.run(debug=True)
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<h1>Success</h1>
{{ data }}
</body>
</html>
@chewarer
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chewarer commented Oct 14, 2016

Thanks for the example.
It's my code:

choices = [(1, 'one'),
           (2, 'two'),
           (3, 'tree')]
resident = MultiCheckboxField('Label',
                              choices=choices, coerce=int)

In my form this checkboxes displayed as intended. But on page with form results, I can render only key of choice(number). How to render a text value of choice?
In Jinja template:

{% if form.resident %}
    {{ form.resident.data }}
{% endif %}

@YohanObadia
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YohanObadia commented Jul 30, 2017

Would have been great to see how your example.html is made.

@gianlucascoccia
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gianlucascoccia commented Nov 9, 2017

Very helpful, thank you!

@pickboy900
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pickboy900 commented Jan 25, 2018

You don't know how valuable it is for me.

Thanks

@insomniac807
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insomniac807 commented Mar 22, 2018

Yeah I would like to see how it is rendered in the html template. For me the border only surrounds the first option which makes it look very messy. a shame because the rest works beautifully

@Skillz-Interface
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Skillz-Interface commented Apr 10, 2018

Thank you

@samuelvarghese
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samuelvarghese commented Aug 3, 2018

Any idea on how the example.html should be structured ? I'm not able to figure it out.

@MarcosMoss
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MarcosMoss commented Aug 27, 2018

what does your Models.py look like?

@adamtongji
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adamtongji commented Feb 25, 2019

Thanks a lot!

@1oh1
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1oh1 commented Apr 19, 2019

example.html

<html>
  <body>
    <form method="post">
      {{ form.csrf_token }}
      {{ form.example }}
      <input type="submit">
    </form>
  </body>
</html>

@shyenatech
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shyenatech commented Mar 8, 2020

The form.validate_on_submit() does not work in this case. It considers the values as invalid. Hence use form.is_submitted() to make it work.

if form.is_submitted():
print form.example.data
else:
print form.errors
return render_template('example.html',form=form)

@doobeh
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Author

doobeh commented Mar 9, 2020

@shyenatech-- the code seems (admittedly outdated) but fine, are you sure you're including the csrf token {{ form.hidden_tag() }} to handle the security component? I've updated it for the new version of Flask-WTF here: https://gist.github.com/doobeh/4668212 to give you an idea of how you don't have to skip the important validation step. Good luck!

@MuhammedTech
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MuhammedTech commented Jul 7, 2020

How to query data from db instead of choices=files

@sgarbidonna
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sgarbidonna commented Nov 13, 2020

Hi! How I mark as checked a checkbox? Is for an edit form. Where I need to mark was already marked before on the create

@xelandar
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xelandar commented Sep 12, 2021

Thanks for this code example.

I was struggling with validating the form though. I needed at least one checkbox to be checked. Above comments mentioning form.validate_on_submit() or form.is_submitted() unfortunately didn't help.

After some googling I stumbled on this stackoverflow answer that finally helped.

My final custom validator code:

def validate(self, extra_validators=None):
  if super().validate(extra_validators):
    if not request.form.getlist('example'):
      self.example.errors.append('At least one checkbox must be selected')
      return False
    else:
      return True
      
    return False

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