Simple flask-wtf FieldList usage printing the data structure of the resulting form. Can be run using python simpleapp.py.

simple.html

<form method="post" action="">
    {{ form.name}}
    {{ form.hidden_tag() }}
    <br/>
    {% for entry in form.subforms %}
        {{ entry.subformfield1}}
        <br/>
    {% endfor %}
    <input type="submit"/>
</form>

simpleapp.py

from flask import Flask, render_template
from flask_wtf import FlaskForm
from wtforms import StringField, FormField, FieldList, HiddenField,Form
import calendar

app = Flask(__name__)
app.secret_key = 'simpletest'

class mysubform(Form):
    subformfield1 = StringField('Random  text')


class myMainForm(FlaskForm):
    randommaintext = StringField('Random main text')
    subforms = FieldList(FormField(mysubform), min_entries=2, max_entries=7)


@app.route('/', methods=['post','get'])
def home():
    form = myMainForm()
    if form.validate_on_submit():
        print(form.data)
        #import pdb; pdb.set_trace()
        return render_template('simple.html', form=form)
    print(form.errors)
    return render_template('simple.html', form=form)

if __name__ == '__main__':
    app.run(debug=True)