Python 为什么'；我的WTForms JSON表单更新是否正确？

我正在开发一个web页面，该页面读取JSON并使用WTForms JSON以表单形式呈现。提交表单时，

form.data

不会更新。为什么这不起作用

views.py

：

from flask import render_template, flash, redirect, request
from app import app
from .forms import PolicyForm
import json
import urllib2

@app.route('/policy', methods=['GET', 'POST'])
def policy():
    url = 'http://dcdemoappsrv1:8081/direct/policy?policyNumber=000000005&everything=true&discounts=true&coverages=true&vehicles=true&nonDescribedVehicle=true&applicant=true&drivers=true&namedInsureds=true&additionalListedInsureds=true'
    response = urllib2.urlopen(url).read()
    pol_json = json.loads(response) 

    form = PolicyForm.from_json(pol_json)

    if form.validate_on_submit():
        flash('data=%s' % str(form.data))
        flash('form pol no =%s' % str(form.policyNumber.data))
        return redirect('/index')

    flash('inital data=%s' % str(form.data))
    return render_template('policy.html',  title='Policy Form', form=form)

from wtforms import Form
from wtforms.fields import BooleanField, StringField, TextField, FloatField, FormField, IntegerField, DateField, SubmitField
from wtforms.validators import DataRequired, InputRequired

class Address(Form):
    street = TextField('Street', validators=[InputRequired()])
    street2 = TextField('Street2')
    city = TextField('City', validators=[InputRequired()])
    state = TextField('State', validators=[InputRequired()])
    zip = TextField('Zip', validators=[InputRequired()])
    county = TextField('County', validators=[InputRequired()])
    latitude = FloatField('Latitude')
    longitude = FloatField('Longitude')
    id = StringField('ID')

class Applicant(Form):
    firstName = TextField('First Name', validators=[InputRequired()])
    lastName = TextField('Last Name', validators=[InputRequired()])
    birthDate = DateField('Birth Date', validators=[InputRequired()])
    age = IntegerField('Age', validators=[InputRequired()])
    id = StringField('ID')

class PolicyForm(Form):
    policyNumber = TextField('Policy Number')
    applicant = FormField(Applicant, label='Applicant')
    address = FormField(Address, label='Address')

forms.py

：

from flask import render_template, flash, redirect, request
from app import app
from .forms import PolicyForm
import json
import urllib2

@app.route('/policy', methods=['GET', 'POST'])
def policy():
    url = 'http://dcdemoappsrv1:8081/direct/policy?policyNumber=000000005&everything=true&discounts=true&coverages=true&vehicles=true&nonDescribedVehicle=true&applicant=true&drivers=true&namedInsureds=true&additionalListedInsureds=true'
    response = urllib2.urlopen(url).read()
    pol_json = json.loads(response) 

    form = PolicyForm.from_json(pol_json)

    if form.validate_on_submit():
        flash('data=%s' % str(form.data))
        flash('form pol no =%s' % str(form.policyNumber.data))
        return redirect('/index')

    flash('inital data=%s' % str(form.data))
    return render_template('policy.html',  title='Policy Form', form=form)

from wtforms import Form
from wtforms.fields import BooleanField, StringField, TextField, FloatField, FormField, IntegerField, DateField, SubmitField
from wtforms.validators import DataRequired, InputRequired

class Address(Form):
    street = TextField('Street', validators=[InputRequired()])
    street2 = TextField('Street2')
    city = TextField('City', validators=[InputRequired()])
    state = TextField('State', validators=[InputRequired()])
    zip = TextField('Zip', validators=[InputRequired()])
    county = TextField('County', validators=[InputRequired()])
    latitude = FloatField('Latitude')
    longitude = FloatField('Longitude')
    id = StringField('ID')

class Applicant(Form):
    firstName = TextField('First Name', validators=[InputRequired()])
    lastName = TextField('Last Name', validators=[InputRequired()])
    birthDate = DateField('Birth Date', validators=[InputRequired()])
    age = IntegerField('Age', validators=[InputRequired()])
    id = StringField('ID')

class PolicyForm(Form):
    policyNumber = TextField('Policy Number')
    applicant = FormField(Applicant, label='Applicant')
    address = FormField(Address, label='Address')

{%extends“base.html”%}
{%block content%}
政策
{%import“\uu formhelpers.html”作为表单%}
{{forms.render（form）}

{%endblock%}

formhelpers.html

：

{%macro render（form）%}
{如果field.type不在[“HiddenField”，“CSRFTokenField”]%中，则表单中的字段为%
{{field.label}
{{field}}
{%if field.errors%}

{%字段中有错误。错误%}
{{error}}
{%endfor%}

{%endif%}
{%endfor%}
{{form.hidden_tag（）}}
{%endmacro%}

您总是用远程JSON数据填充表单。您只应在首次提交表单时执行此操作，而不应在处理提交的数据时执行此操作

# ...
if not form.is_submitted():
    data = json.load(urllib2.urlopen(url))
    form = PolicyForm.from_json(data)
else:
    form = PolicyForm()  # will populate from submitted data

if form.validate_on_submit():
# ...