MIDDLEWARE = [
        # Django's "default" middleware, in the appropriate order according to Django 3 docs.
        ...

        # Wagtail's SiteMiddleware
        wagtail.contrib.legacy.SiteMiddleware',

        # Enables the use of the get_current_request() and get_current_user() functions.
        'crequest.middleware.CrequestMiddleware',
    ]

    @register_setting
    class Features(BaseSetting):
        """
        This is a Settings model that has a one-to-one relationship with each Site in the system.
        It stores json blobs that configure its Site's available features. Features are defined through the
        "register_feature" hook, and can have two types:

        1) Default Features. These features ere enabled by default on all Sites, but can be explicitly disabled via the
           Features form. These include features like particular Block types.
        2) Special Features. These are features that are only used by a small subset of the Sites on a system, and are
           therefore disabled by default. They can be enabled through the Features form.
           These include features like HSS's Working Papers, or the Startup Map used by OTTCP.

        Implementing what "disabling" a Default Feature, or "enabling" a Special Feature actually means is left up to the
        code that registers the feature. This module only stores the data for which Site enables/disables which Features.
        """
        THEMES = [
            (THEME_61, 'v6.1'),
            (THEME_70, 'v7.0'),
        ]

        # FIELDS
        disabled_defaults = jsonfield.JSONField(default=[])
        enabled_specials = jsonfield.JSONField(default=[])
        site_theme = models.CharField(
            "Site Theme",
            max_length=10,
            choices=THEMES,
            default=THEME_70,
            help_text="This setting is only visible to superusers. DO NOT CHANGE THIS SETTING ON ESTABLISHED SITES."
        )

        # FORM CONFIG
        panels = [
            FieldPanel('disabled_defaults', classname='disabled-defaults'),
            FieldPanel('enabled_specials', classname='enabled-specials'),
            FieldPanel('site_theme', classname='site-theme'),
        ]
        base_form_class = FeaturesForm

        def feature_is_enabled(self, machine_name):
            """
            Returns True if the Feature with the given machine name is enabled on the associated Site.
            Since machine names cannot be shared across Special and Default features, this method works for both types.
            """
            if machine_name in registry['special']:
                return machine_name in self.enabled_specials
            elif machine_name in registry['default']:
                return machine_name not in self.disabled_defaults
            else:
                raise UnknownFeatureMachineNameError("No Feature exists with the machine name '{}'".format(machine_name))

        class Meta:
            verbose_name = 'Site Features'

    class FeaturesForm(WagtailAdminModelForm):
        css_class = "features-form rich-settings"

        disabled_defaults = forms.MultipleChoiceField(
            required=False,
            widget=forms.CheckboxSelectMultiple,
            label='Disabled Default Features',
            choices=[],
            help_text=mark_safe("Select Default Features that should be <b>disabled</b> on this Site.")
        )
        enabled_specials = forms.MultipleChoiceField(
            required=False,
            widget=forms.CheckboxSelectMultiple,
            label='Enabled Special Features',
            choices=[],
            help_text=mark_safe("Select Special Features that should be <b>enabled</b> on this Site.")
        )

        def __init__(self, *args, **kwargs):
            super().__init__(*args, **kwargs)
            self.fields['disabled_defaults'].choices = sorted(registry['default'].items())
            self.fields['enabled_specials'].choices = sorted(registry['special'].items())

    class FlexPage(BasePage):
        # field definitions here
        bare_page = models.BooleanField(default=False, help_text="Render the page without a header or footer.")

        # Editor Panels Configuration
        flex_content_panels = [
            FieldPanel('title', classname='full title'),
            FieldPanel('body')
        ]

        flex_settings_panels = [
            MultiFieldPanel(
                heading='Page Settings',
                children=[
                    FieldPanel('slug'),
                    FieldPanel('bare_page'),
                ]
            )
        ]

        edit_handler = TabbedInterface(
            base_form_class=BarePageForm,
            children=[
                ObjectList(flex_content_panels, heading='Content'),
                ObjectList(flex_settings_panels, heading='Settings', classname='settings'),
                ObjectList(flex_publishing_panels, heading='Publishing'),
            ]
        )

--------------------------------

    class BarePageForm(WagtailAdminPageForm):

        def __init__(self, *args, **kwargs):
            """
            Starting with Wagtail 3, we do our form manipulation in the form class initializer,
            not in a get_edit_handler class method.
            """
            super().__init__(*args, **kwargs)

            request = get_current_request()
            if request and not Site.find_for_request(request).features.feature_is_enabled('bare_page'):
                del self.fields['bare_page']

    MultiFieldPanel(
        heading='Admin-only Fields',
        # NOTE: The 'admin-only' class is how EventPage.get_edit_handler() identifies this MultiFieldPanel.
       classname='collapsible admin-only',
        children=[
           FieldPanel('display_locations', widget=forms.CheckboxSelectMultiple),
           StreamFieldPanel('assets'),
        ]
    ),

    @classmethod
    def get_edit_handler(cls):
        """
        We override this method (which is added to the Page class in wagtail.admin.panels) in order to enforce
        our custom field-level permissions.
        """
        # Do the same thing that wagtail.admin.panels.get_edit_handler() would do...
        bound_handler = cls.edit_handler.bind_to(model=cls)
        # ... then enforce admin-only field permissions on the result.
        current_request = get_current_request()
        # This method gets called during certain manage.py commands, so we need to be able to gracefully fail if there
        # is no current request. Thus, if there is no current request, the admin-only fields are removed.
        if current_request is None or not current_request.user.has_perm('master_calendar.can_access_admin_fields'):
            # We know for sure that bound_handler.children[0].children is the list of Panels in the Content tab.
            # We must search through that list to find the admin-only MultiFieldPanel, and remove it.
            # The [:] gets us a copy of the list, so altering the original doesn't change what we're looping over.
            for child in bound_handler.children[0].children[:]:
                if 'admin-only' in child.classname:
                    bound_handler.children[0].children.remove(child)
                    break
        return bound_handler

    MultiFieldPanel(
        heading='Admin-only Fields',
        classname='collapsible',
        children=[
            FieldPanel('display_locations', permission='master_calendar.can_access_admin_fields',
                       widget=forms.CheckboxSelectMultiple),
            FieldPanel('assets', permission='master_calendar.can_access_admin_fields'),
        ]
    ),

  # wagtail_patches/monkey_patches.py

  import wagtail.core.fields

  def deconstruct_without_block_definition(self):
      name, path, _, kwargs = super(wagtail.core.fields.StreamField, self).deconstruct()
      block_types = list()
      args = [block_types]
      return name, path, args, kwargs
  wagtail.core.fields.StreamField.deconstruct = deconstruct_without_block_definition

  body = wagtail.core.fields.StreamField([ <large list of blocks here> ])

  ('body', wagtail.core.fields.StreamField([]))

  # app/management/commands/__init__.py

  """
  Django creates redundant migrations for Django model changes that do not alter the database.
  Here we patch Django's migration machinery to ignore attrs.

  The management commands `makemigrations` and `migrate` will ignore the attrs defined in:

      - MIGRATION_IGNORE_MODEL_ATTRS
      - MIGRATION_IGNORE_FIELD_ATTRS
      - MIGRATION_IGNORE_FILE_FIELD_ATTRS
      - MIGRATION_IGNORE_RELATED_FIELD_ATTRS

  This will reduce the number of migrations and therefore speed-up development
  """

  import logging
  from functools import wraps

  from django.db.migrations.operations import AlterModelOptions
  from django.db.models import Field, FileField
  from django.db.models.fields.related import RelatedField

  logger = logging.getLogger(__name__)

  MIGRATION_IGNORE_MODEL_ATTRS = ["verbose_name", "verbose_name_plural"]
  MIGRATION_IGNORE_FIELD_ATTRS = ["validators", "choices", "help_text", "verbose_name"]
  MIGRATION_IGNORE_FILE_FIELD_ATTRS = ["upload_to", "storage"]

  MIGRATION_IGNORE_RELATED_FIELD_ATTRS = ["related_name", "related_query_name"]

  for attr in MIGRATION_IGNORE_MODEL_ATTRS:
      logger.info(f"Model {attr} attr will be ignored.")

  for attr in MIGRATION_IGNORE_FIELD_ATTRS:
      logger.info(f"Field {attr} attr will be ignored.")

  for attr in MIGRATION_IGNORE_FILE_FIELD_ATTRS:
      logger.info(f"File field {attr} attr will be ignored.")

  for attr in MIGRATION_IGNORE_RELATED_FIELD_ATTRS:
      logger.info(f"Related field {attr} attr will be ignored.")


  def patch_ignored_model_attrs(cls):
      for attr in MIGRATION_IGNORE_MODEL_ATTRS:
          cls.ALTER_OPTION_KEYS.remove(attr)


  def patch_field_deconstruct(old_func):
      @wraps(old_func)
      def deconstruct_with_ignored_attrs(self):
          name, path, args, kwargs = old_func(self)
          for attr in MIGRATION_IGNORE_FIELD_ATTRS:
              kwargs.pop(attr, None)
          return name, path, args, kwargs

      return deconstruct_with_ignored_attrs


  def patch_file_field_deconstruct(old_func):
      @wraps(old_func)
      def deconstruct_with_ignored_attrs(self):
          name, path, args, kwargs = old_func(self)
          for attr in MIGRATION_IGNORE_FILE_FIELD_ATTRS:
              kwargs.pop(attr, None)
          return name, path, args, kwargs

      return deconstruct_with_ignored_attrs


  def patch_related_field_deconstruct(old_func):
      @wraps(old_func)
      def deconstruct_with_ignored_attrs(self):
          name, path, args, kwargs = old_func(self)
          for attr in MIGRATION_IGNORE_RELATED_FIELD_ATTRS:
              kwargs.pop(attr, None)
          return name, path, args, kwargs

      return deconstruct_with_ignored_attrs


  Field.deconstruct = patch_field_deconstruct(Field.deconstruct)
  FileField.deconstruct = patch_file_field_deconstruct(FileField.deconstruct)
  RelatedField.deconstruct = patch_related_field_deconstruct(RelatedField.deconstruct)
  patch_ignored_model_attrs(AlterModelOptions)

  # app/management/commands/makemigrations.py

  """
  Override of Django makemigrations. When we use this version, we
  will load the __init__ file above that patches models.Field.
  """

  from django.core.management.commands.makemigrations import Command  # noqa

  # app/management/commands/migrate.py

  """
  Override of Django migrate. When we use this version, we
  will load the __init__ file above that patches models.Field.
  """

  from django.core.management.commands.migrate import Command  # noqa