title: SelectField forces me to select a choice from drop down
body: <p>I'm creating a flask form which has the email, address, state, postal code and country. Only the email is a mandatory field. None of the others are. However, Flask WTForms is forcing the user to select a state and a country from the drop down.</p>
  
  <p>State and Country are both drop down options.</p>
  
  <pre><code>class UserForm(FlaskForm):
      email = EmailField('E-Mail', validators=[InputRequired()])
      address1 = StringField('Address line 1', render_kw={"placeholder": "Address line 1"})
      address2 = StringField('Address line 2', render_kw={"placeholder": "Address line 2"})
      city = StringField('City', render_kw={"placeholder": "City"})
      state = SelectField('State', [validators.Optional()], default=None, choices=statesList(), render_kw={"placeholder": "State"})
      postal_code = StringField('Postal Code', render_kw={"placeholder": "Postal Code"})
      country = SelectField('Country', default=None, choices=countriesList(), coerce=str, render_kw={"placeholder": "Country"})
  
  @app.route('/create_user', methods=['GET', 'POST'])
  def createUser():
      form=UserForm()
      if form.validate_on_submit():
          return render_template('confirm_user.html', email=form.email.data,
  address1=form.address1.data,
  address2=form.address2.data,
  city=form.city.data,
  state=form.state.data,
  postal_code=form.postal_code.data,
  country=form.country.data)
  </code></pre>
  
  <p>I even made the state an optional field. This only happens to drop-down fields.</p>
  
  <p>I looked at a couple of posts on StackOverflow already but they do not answer this. Those posts suggest that the choices be removed. I need the state and country drop downs to be visible but the user does not need to make a selection if they don't want to. In this case, I'll just return a blank value to the database.</p>
  
  <p>Can someone tell me how I can achieve this please?</p>