@blueprint.route("/register/", defaults={'token': ''}, methods=['GET', 'POST'])
@blueprint.route("/register/<token>", methods=['GET', 'POST'])
def register(token):
    form = RegisterForm(request.form, csrf_enabled=False)
    email = confirm_token(token)
    if form.validate_on_submit():
        new_user = User.create(username=form.username.data,
                               first_name=form.first_name.data,
                               last_name=form.last_name.data,
                               email=form.email.data,
                               password=form.password.data,
                               active=True)
        new_user = User.create(email=form.email.data, password=form.password.data, active=True)
        flash("Thank you for registering. You can now log in.", 'success')
        return redirect(url_for('public.home'))
    else:
        flash_errors(form)
    return render_template('public/register.html', form=form , email=email)

<h1>Register</h1>
<br/>
<form id="registerForm" class="form form-register" method="POST" action="" role="form">

        {% for field in form %}
            {% print(field.name)%}
            {% if field.label.text =='Email' %}
                {% set field.data=email %}
            {% else %}
                {{ render_field(field) }}
            {% endif %}
        {% endfor %}
        <p><input class="btn btn-default btn-submit" type="submit" value="register"></p>
</form>

{% set field.data=email %}

Traceback (most recent call last):
File "C:envsvirtalenvsflask_minilibsite-packagesflaskapp.py", line 1836, in __call__
  return self.wsgi_app(environ, start_response)
File "C:envsvirtalenvsflask_minilibsite-packagesflaskapp.py", line 1820, in wsgi_app
  response = self.make_response(self.handle_exception(e))
File "C:envsvirtalenvsflask_minilibsite-packagesflaskapp.py", line 1403, in handle_exception
  reraise(exc_type, exc_value, tb)
File "C:envsvirtalenvsflask_minilibsite-packagesflaskapp.py", line 1817, in wsgi_app
  response = self.full_dispatch_request()
File "C:envsvirtalenvsflask_minilibsite-packagesflaskapp.py", line 1477, in full_dispatch_request
  rv = self.handle_user_exception(e)
File "C:envsvirtalenvsflask_minilibsite-packagesflaskapp.py", line 1381, in handle_user_exception
  reraise(exc_type, exc_value, tb)
File "C:envsvirtalenvsflask_minilibsite-packagesflaskapp.py", line 1475, in full_dispatch_request
  rv = self.dispatch_request()
File "C:envsvirtalenvsflask_minilibsite-packagesflask_debugtoolbar__init__.py", line 124, in dispatch_request
  return view_func(**req.view_args)
File "C:envsr2minimyflaskappviewspublic.py", line 73, in register
  return render_template('public/register.html', form=form , email=email)
File "C:envsvirtalenvsflask_minilibsite-packagesflasktemplating.py", line 127, in render_template
  return _render(ctx.app.jinja_env.get_or_select_template(template_name_or_list),
File "C:envsvirtalenvsflask_minilibsite-packagesjinja2environment.py", line 830, in get_or_select_template
  return self.get_template(template_name_or_list, parent, globals)
File "C:envsvirtalenvsflask_minilibsite-packagesjinja2environment.py", line 791, in get_template
  return self._load_template(name, self.make_globals(globals))
File "C:envsvirtalenvsflask_minilibsite-packagesjinja2environment.py", line 765, in _load_template
  template = self.loader.load(self, name, globals)
File "C:envsvirtalenvsflask_minilibsite-packagesjinja2loaders.py", line 125, in load
  code = environment.compile(source, name, filename)
File "C:envsvirtalenvsflask_minilibsite-packagesjinja2environment.py", line 554, in compile
  self.handle_exception(exc_info, source_hint=source)
File "C:envsvirtalenvsflask_minilibsite-packagesjinja2environment.py", line 742, in handle_exception
  reraise(exc_type, exc_value, tb)
File "C:envsr2minimyflaskapptemplatespublicregister.html", line 15, in template
  {% set field.data=email %}
 TemplateSyntaxError: expected token '=', got '.'