Translation management models

def get_instance(self, locale):
    """
    Returns a model instance for this object in the given locale.

    Args:
        locale (Locale | int): Either a Locale object or an ID of a Locale.

    Returns:
        Model: The model instance.

    Raises:
        Model.DoesNotExist: If there is not an instance of this object in the given locale.
    """
    return self.content_type.get_object_for_this_type(
        translation_key=self.translation_key, locale_id=pk(locale)
    )

def get_instance_or_none(self, locale):
    """
    Returns a model instance for this object in the given locale.

    Args:
        locale (Locale | int): Either a Locale object or an ID of a Locale.

    Returns:
        Model: The model instance if one exists.
        None: If the model doesn't exist.
    """
    try:
        return self.get_instance(locale)
    except self.content_type.model_class().DoesNotExist:
        pass

def has_translation(self, locale):
    """
    Returns True if there is an instance of this object in the given Locale.

    Args:
        locale (Locale | int): Either a Locale object or an ID of a Locale.

    Returns:
        bool: True if there is an instance of this object in the given locale.
    """
    return self.content_type.get_all_objects_for_this_type(
        translation_key=self.translation_key, locale_id=pk(locale)
    ).exists()

def export_po(self):
    """
    Exports all translatable strings with any translations that have already been made.

    Returns:
        polib.POFile: A POFile object containing the source translatable strings and any translations.
    """
    # Get messages
    messages = []

    string_segments = (
        StringSegment.objects.filter(source=self.source)
        .order_by("order")
        .select_related("context", "string")
        .annotate_translation(self.target_locale, include_errors=True)
    )

    for string_segment in string_segments:
        messages.append(
            (
                string_segment.string.data,
                string_segment.context.path,
                string_segment.translation,
            )
        )

    # Build a PO file
    po = polib.POFile(wrapwidth=200)
    po.metadata = {
        "POT-Creation-Date": str(timezone.now()),
        "MIME-Version": "1.0",
        "Content-Type": "text/plain; charset=utf-8",
        "X-WagtailLocalize-TranslationID": str(self.uuid),
    }

    for text, context, translation in messages:
        po.append(
            polib.POEntry(
                msgid=text,
                msgctxt=context,
                msgstr=translation or "",
            )
        )

    # Add any obsolete segments that have translations for future reference
    # We find this by looking for obsolete contexts and annotate the latest
    # translation for each one. Contexts that were never translated are
    # excluded
    for translation in (
        StringTranslation.objects.filter(
            context__object_id=self.source.object_id, locale=self.target_locale
        )
        .exclude(
            translation_of_id__in=StringSegment.objects.filter(
                source=self.source
            ).values_list("string_id", flat=True)
        )
        .select_related("translation_of", "context")
        .iterator()
    ):
        po.append(
            polib.POEntry(
                msgid=translation.translation_of.data,
                msgstr=translation.data or "",
                msgctxt=translation.context.path,
                obsolete=True,
            )
        )

    return po

def get_progress(self):
    """
    Gets the current translation progress.

    Returns
        tuple[int, int]: A two-tuple of integers. First integer is the total number of string segments to be translated.
            The second integer is the number of string segments that have been translated so far.
    """
    # Get QuerySet of Segments that need to be translated
    required_segments = StringSegment.objects.filter(source_id=self.source_id)

    # Annotate each Segment with a flag that indicates whether the segment is translated
    # into the locale
    required_segments = required_segments.annotate(
        is_translated=Exists(
            StringTranslation.objects.filter(
                translation_of_id=OuterRef("string_id"),
                context_id=OuterRef("context_id"),
                locale_id=self.target_locale_id,
                has_error=False,
            )
        )
    )

    # Count the total number of segments and the number of translated segments
    aggs = required_segments.annotate(
        is_translated_i=Case(
            When(is_translated=True, then=Value(1)),
            default=Value(0),
            output_field=IntegerField(),
        )
    ).aggregate(
        total_segments=Count("pk"), translated_segments=Sum("is_translated_i")
    )

    return aggs["total_segments"], aggs["translated_segments"]

def get_status_display(self):
    """
    Returns a string to describe the current status of this translation to a user.

    Returns:
        str: The status of this translation
    """
    total_segments, translated_segments = self.get_progress()
    if total_segments == translated_segments:
        return _("Up to date")
    else:
        return _("Waiting for translations")

def get_target_instance(self):
    """
    Fetches the translated instance from the database.

    Raises:
        Model.DoesNotExist: if the translation does not exist.

    Returns:
        Model: The translated instance.
    """
    return self.source.get_translated_instance(self.target_locale)

def get_target_instance_edit_url(self):
    """
    Returns the URL to edit the target instance.

    Raises:
        Model.DoesNotExist: if the translation does not exist.

    Returns:
        str: The URL of the edit view of the target instance.
    """
    return get_edit_url(self.get_target_instance())

@transaction.atomic
def import_po(
    self, po, delete=False, user=None, translation_type="manual", tool_name=""
):
    """
    Imports all translatable strings with any translations that have already been made.

    Args:
        po (polib.POFile): A POFile object containing the source translatable strings and any translations.
        delete (boolean, optional): Set to True to delete any translations that do not appear in the PO file.
        user (User, optional): The user who is performing this operation. Used for logging purposes.
        translation_type ('manual' or 'machine', optional): Whether the translationw as performed by a human or machine. Defaults to 'manual'.
        tool_name (string, optional): The name of the tool that was used to perform the translation. Defaults to ''.

    Returns:
        list[POImportWarning]: A list of POImportWarning objects representing any non-fatal issues that were
        encountered while importing the PO file.
    """
    seen_translation_ids = set()
    warnings = []

    if "X-WagtailLocalize-TranslationID" in po.metadata and po.metadata[
        "X-WagtailLocalize-TranslationID"
    ] != str(self.uuid):
        return []

    for index, entry in enumerate(po):
        try:
            string = String.objects.get(
                locale_id=self.source.locale_id, data=entry.msgid
            )
            context = TranslationContext.objects.get(
                object_id=self.source.object_id, path=entry.msgctxt
            )

            # Ignore blank strings
            if not entry.msgstr:
                continue

            # Ignore if the string doesn't appear in this context, and if there is not an obsolete StringTranslation
            if (
                not StringSegment.objects.filter(
                    string=string, context=context
                ).exists()
                and not StringTranslation.objects.filter(
                    translation_of=string, context=context
                ).exists()
            ):
                warnings.append(
                    StringNotUsedInContext(index, entry.msgid, entry.msgctxt)
                )
                continue

            string_translation, created = string.translations.get_or_create(
                locale_id=self.target_locale_id,
                context=context,
                defaults={
                    "data": entry.msgstr,
                    "updated_at": timezone.now(),
                    "translation_type": translation_type,
                    "tool_name": tool_name,
                    "last_translated_by": user,
                    "has_error": False,
                    "field_error": "",
                },
            )

            seen_translation_ids.add(string_translation.id)

            if not created:
                # Update the string_translation only if it has changed
                if string_translation.data != entry.msgstr:
                    string_translation.data = entry.msgstr
                    string_translation.translation_type = translation_type
                    string_translation.tool_name = tool_name
                    string_translation.last_translated_by = user
                    string_translation.updated_at = timezone.now()
                    string_translation.has_error = False  # reset the error flag.
                    string_translation.save()

        except TranslationContext.DoesNotExist:
            warnings.append(UnknownContext(index, entry.msgctxt))

        except String.DoesNotExist:
            warnings.append(UnknownString(index, entry.msgid))

    # Delete any translations that weren't mentioned
    if delete:
        StringTranslation.objects.filter(
            context__object_id=self.source.object_id, locale=self.target_locale
        ).exclude(id__in=seen_translation_ids).delete()

    return warnings

def save_target(self, user=None, publish=True):
    """
    Saves the target page/snippet using the current translations.

    Args:
        user (User, optional): The user that is performing this action. Used for logging purposes.
        publish (boolean, optional): Set this to False to save a draft of the translation. Pages only.

    Raises:
        SourceDeletedError: if the source object has been deleted.
        CannotSaveDraftError: if the `publish` parameter was set to `False` when translating a non-page object.
        MissingTranslationError: if a translation is missing and `fallback `is not `True`.
        MissingRelatedObjectError: if a related object is not translated and `fallback `is not `True`.

    Returns:
        Model: The translated instance.
    """
    self.source.create_or_update_translation(
        self.target_locale,
        user=user,
        publish=publish,
        fallback=True,
        copy_parent_pages=True,
    )

def get_instance(self):
    """
    Gets the instance of the translated object, if it still exists.

    Raises:
        Model.DoesNotExist: if the translated object no longer exists.

    Returns:
        The translated object.
    """
    return self.source.object.get_instance(self.locale)

def _get_segments_for_translation(self, locale, fallback=False):
    """
    Returns a list of segments that can be passed into "ingest_segments" to translate an object.
    """
    string_segments = (
        StringSegment.objects.filter(source=self)
        .annotate_translation(locale)
        .select_related("context", "string")
    )

    template_segments = (
        TemplateSegment.objects.filter(source=self)
        .select_related("template")
        .select_related("context")
    )

    related_object_segments = (
        RelatedObjectSegment.objects.filter(source=self)
        .select_related("object")
        .select_related("context")
    )

    overridable_segments = (
        OverridableSegment.objects.filter(source=self)
        .annotate_override_json(locale)
        .filter(override_json__isnull=False)
        .select_related("context")
    )

    segments = []

    for string_segment in string_segments:
        if string_segment.translation:
            string = StringValue(string_segment.translation)
        elif fallback:
            string = StringValue(string_segment.string.data)
        else:
            raise MissingTranslationError(string_segment, locale)

        segment_value = StringSegmentValue(
            string_segment.context.path,
            string,
            attrs=json.loads(string_segment.attrs),
        ).with_order(string_segment.order)

        segments.append(segment_value)

    for template_segment in template_segments:
        template = template_segment.template
        segment_value = TemplateSegmentValue(
            template_segment.context.path,
            template.template_format,
            template.template,
            template.string_count,
            order=template_segment.order,
        )
        segments.append(segment_value)

    for related_object_segment in related_object_segments:
        if related_object_segment.object.has_translation(locale):
            segment_value = RelatedObjectSegmentValue(
                related_object_segment.context.path,
                related_object_segment.object.content_type,
                related_object_segment.object.translation_key,
                order=related_object_segment.order,
            )
            segments.append(segment_value)

        elif fallback:
            # Skip this segment, this will reuse what is already in the database
            continue
        else:
            raise MissingRelatedObjectError(related_object_segment, locale)

    for overridable_segment in overridable_segments:
        segment_value = OverridableSegmentValue(
            overridable_segment.context.path,
            json.loads(overridable_segment.override_json),
            order=overridable_segment.order,
        )
        segments.append(segment_value)

    return segments

def as_instance(self):
    """
    Builds an instance of the object with the content of this source.

    Returns:
        Model: A model instance that has the content of this TranslationSource.

    Raises:
        SourceDeletedError: if the source instance has been deleted.
    """
    try:
        instance = self.get_source_instance()
    except models.ObjectDoesNotExist:
        raise SourceDeletedError

    if isinstance(instance, Page):
        # see https://github.com/wagtail/wagtail/pull/8024
        content_json = json.loads(self.content_json)
        return instance.with_content_json(content_json)

    elif isinstance(instance, ClusterableModel):
        new_instance = instance.__class__.from_json(self.content_json)

    else:
        new_instance = model_from_serializable_data(
            instance.__class__, json.loads(self.content_json)
        )

    new_instance.pk = instance.pk
    new_instance.locale = instance.locale
    new_instance.translation_key = instance.translation_key

    return new_instance

def create_or_update_translation(
    self, locale, user=None, publish=True, copy_parent_pages=False, fallback=False
):
    """
    Creates/updates a translation of the object into the specified locale
    based on the content of this source and the translated strings
    currently in translation memory.

    Args:
        locale (Locale): The target locale to generate the translation for.
        user (User, optional): The user who is carrying out this operation. For logging purposes
        publish (boolean, optional): Set this to False to save a draft of the translation. Pages only.
        copy_parent_pages (boolean, optional): Set this to True to make copies of the parent pages if they are not
            yet translated.
        fallback (boolean, optional): Set this to True to fallback to source strings/related objects if they are
            not yet translated. By default, this will raise an error if anything is missing.

    Raises:
        SourceDeletedError: if the source object has been deleted.
        CannotSaveDraftError: if the `publish` parameter was set to `False` when translating a non-page object.
        MissingTranslationError: if a translation is missing and `fallback `is not `True`.
        MissingRelatedObjectError: if a related object is not translated and `fallback `is not `True`.

    Returns:
        Model: The translated instance.
    """
    original = self.as_instance()
    created = False

    # Only pages can be saved as draft
    if not publish and not isinstance(original, Page):
        raise CannotSaveDraftError

    try:
        translation = self.get_translated_instance(locale)
    except models.ObjectDoesNotExist:
        if isinstance(original, Page):
            translation = original.copy_for_translation(
                locale, copy_parents=copy_parent_pages
            )
        else:
            translation = original.copy_for_translation(locale)

        created = True

    copy_synchronised_fields(original, translation)

    segments = self._get_segments_for_translation(locale, fallback=fallback)

    try:
        with transaction.atomic():
            # Ingest all translated segments
            ingest_segments(original, translation, self.locale, locale, segments)

            if isinstance(translation, Page):
                # If the page is an alias, convert it into a regular page
                if translation.alias_of_id:
                    translation.alias_of_id = None
                    translation.save(update_fields=["alias_of_id"], clean=False)

                    # Create initial revision
                    revision = translation.save_revision(
                        user=user, changed=False, clean=False
                    )

                    # Log the alias conversion
                    PageLogEntry.objects.log_action(
                        instance=translation,
                        revision=revision,
                        action="wagtail.convert_alias",
                        user=user,
                        data={
                            "page": {
                                "id": translation.id,
                                "title": translation.get_admin_display_title(),
                            },
                        },
                    )

                # Make sure the slug is valid
                translation.slug = find_available_slug(
                    translation.get_parent(),
                    slugify(translation.slug),
                    ignore_page_id=translation.id,
                )
                translation.save()

                # Create a new revision
                page_revision = translation.save_revision(user=user)

                self.sync_view_restrictions(original, translation)

                if publish:
                    page_revision.publish()

            else:
                # Note: we don't need to run full_clean for Pages as Wagtail does that in Page.save()
                translation.full_clean()

                translation.save()
                page_revision = None

    except ValidationError as e:
        # If the validation error's field matches the context of a translation,
        # set that error message on that translation.
        # TODO (someday): Add support for errors raised from streamfield
        for field_name, errors in e.error_dict.items():
            try:
                context = TranslationContext.objects.get(
                    object=self.object, path=field_name
                )

            except TranslationContext.DoesNotExist:
                # TODO (someday): How would we handle validation errors for non-translatable fields?
                continue

            # Check for string translation
            try:
                string_translation = StringTranslation.objects.get(
                    translation_of_id__in=StringSegment.objects.filter(
                        source=self
                    ).values_list("string_id", flat=True),
                    context=context,
                    locale=locale,
                )

                string_translation.set_field_error(errors)

            except StringTranslation.DoesNotExist:
                pass

            # Check for segment override
            try:
                segment_override = SegmentOverride.objects.get(
                    context=context,
                    locale=locale,
                )

                segment_override.set_field_error(errors)

            except SegmentOverride.DoesNotExist:
                pass

        raise

    # Log that the translation was made
    TranslationLog.objects.create(
        source=self, locale=locale, page_revision=page_revision
    )

    return translation, created

def export_po(self):
    """
    Exports all translatable strings from this source.

    Note that because there is no target locale, all `msgstr` fields will be blank.

    Returns:
        polib.POFile: A POFile object containing the source translatable strings.
    """
    # Get messages
    messages = []

    for string_segment in (
        StringSegment.objects.filter(source=self)
        .order_by("order")
        .select_related("context", "string")
    ):
        messages.append((string_segment.string.data, string_segment.context.path))

    # Build a PO file
    po = polib.POFile(wrapwidth=200)
    po.metadata = {
        "POT-Creation-Date": str(timezone.now()),
        "MIME-Version": "1.0",
        "Content-Type": "text/plain; charset=utf-8",
    }

    for text, context in messages:
        po.append(
            polib.POEntry(
                msgid=text,
                msgctxt=context,
                msgstr="",
            )
        )

    return po

def get_ephemeral_translated_instance(self, locale, fallback=False):
    """
    Returns an instance with the translations added which is not intended to be saved.

    This is used for previewing pages with draft translations applied.

    Args:
        locale (Locale): The target locale to generate the ephemeral translation for.
        fallback (boolean): Set this to True to fallback to source strings/related objects if they are not yet
            translated. By default, this will raise an error if anything is missing.

    Raises:
        SourceDeletedError: if the source object has been deleted.
        MissingTranslationError: if a translation is missing and `fallback `is not `True`.
        MissingRelatedObjectError: if a related object is not translated and `fallback `is not `True`.

    Returns:
        Model: The translated instance with unsaved changes.
    """
    original = self.as_instance()
    translation = self.get_translated_instance(locale)

    copy_synchronised_fields(original, translation)

    segments = self._get_segments_for_translation(locale, fallback=fallback)

    # Ingest all translated segments
    ingest_segments(original, translation, self.locale, locale, segments)

    return translation

@classmethod
def get_or_create_from_instance(cls, instance):
    """
    Creates or gets a TranslationSource for the given instance.

    This extracts the content from the given instance. Then stores it in a new TranslationSource instance if one
    doesn't already exist. If one does already exist, it returns the existing TranslationSource without changing
    it.

    Args:
        instance (Model that inherits TranslatableMixin): A Translatable model instance to find a TranslationSource
            instance for.

    Returns:
        tuple[TranslationSource, boolean]: A two-tuple, the first component is the TranslationSource object, and
            the second component is a boolean that is True if the TranslationSource was created.
    """
    # Make sure we're using the specific version of pages
    if isinstance(instance, Page):
        instance = instance.specific

    object, created = TranslatableObject.objects.get_or_create_from_instance(
        instance
    )

    try:
        return (
            TranslationSource.objects.get(
                object_id=object.translation_key, locale_id=instance.locale_id
            ),
            False,
        )
    except TranslationSource.DoesNotExist:
        pass

    if isinstance(instance, ClusterableModel):
        content_json = instance.to_json()
    else:
        serializable_data = get_serializable_data_for_fields(instance)
        content_json = json.dumps(serializable_data, cls=DjangoJSONEncoder)

    source, created = cls.objects.update_or_create(
        object=object,
        locale=instance.locale,
        # You can't update the content type of a source. So if this happens,
        # it'll try and create a new source and crash (can't have more than
        # one source per object/locale)
        specific_content_type=ContentType.objects.get_for_model(instance.__class__),
        defaults={
            "locale": instance.locale,
            "object_repr": str(instance)[:200],
            "content_json": content_json,
            "schema_version": get_schema_version(instance._meta.app_label) or "",
            "last_updated_at": timezone.now(),
        },
    )
    source.refresh_segments()
    return source, created

def get_source_instance(self):
    """
    This gets the live version of instance that the source data was extracted from.

    This is different to source.object.get_instance(source.locale) as the instance
    returned by this methid will have the same model that the content was extracted
    from. The model returned by `object.get_instance` might be more generic since
    that model only records the model that the TranslatableMixin was applied to but
    that model might have child models.

    Returns:
        Model: The model instance that this TranslationSource was created from.

    Raises:
        Model.DoesNotExist: If the source instance has been deleted.
    """
    return self.specific_content_type.get_object_for_this_type(
        translation_key=self.object_id, locale_id=self.locale_id
    )

def get_source_instance_edit_url(self):
    """
    Returns the URL to edit the source instance.
    """
    return get_edit_url(self.get_source_instance())

@transaction.atomic
def refresh_segments(self):
    """
    Updates the *Segment models to reflect the latest version of the source.

    This is called by `from_instance` so you don't usually need to call this manually.
    """
    seen_string_segment_ids = []
    seen_template_segment_ids = []
    seen_related_object_segment_ids = []
    seen_overridable_segment_ids = []

    instance = self.as_instance()
    for segment in extract_segments(instance):
        if isinstance(segment, TemplateSegmentValue):
            segment_obj = TemplateSegment.from_value(self, segment)
            seen_template_segment_ids.append(segment_obj.id)
        elif isinstance(segment, RelatedObjectSegmentValue):
            segment_obj = RelatedObjectSegment.from_value(self, segment)
            seen_related_object_segment_ids.append(segment_obj.id)
        elif isinstance(segment, OverridableSegmentValue):
            segment_obj = OverridableSegment.from_value(self, segment)
            seen_overridable_segment_ids.append(segment_obj.id)
        else:
            segment_obj = StringSegment.from_value(self, self.locale, segment)
            seen_string_segment_ids.append(segment_obj.id)

        # Make sure the segment's field_path is pre-populated
        segment_obj.context.get_field_path(instance)

    # Delete any segments that weren't mentioned
    self.stringsegment_set.exclude(id__in=seen_string_segment_ids).delete()
    self.templatesegment_set.exclude(id__in=seen_template_segment_ids).delete()
    self.relatedobjectsegment_set.exclude(
        id__in=seen_related_object_segment_ids
    ).delete()
    self.overridablesegment_set.exclude(
        id__in=seen_overridable_segment_ids
    ).delete()

def schema_out_of_date(self):
    """
    Returns True if the app that contains the model this source was generated from
    has been updated since the source was last updated.
    """
    if not self.schema_version:
        return False

    current_schema_version = get_schema_version(
        self.specific_content_type.app_label
    )
    return self.schema_version != current_schema_version

def sync_view_restrictions(self, original, translation_page):
    """
    Synchronizes view restriction object for the translated page

    Args:
        original (Page|Snippet): The original instance.
        translation_page (Page|Snippet): The translated instance.
    """
    if not isinstance(original, Page) or not isinstance(translation_page, Page):
        raise NoViewRestrictionsError

    if original.view_restrictions.exists():
        original_restriction = original.view_restrictions.first()
        if not translation_page.view_restrictions.exists():
            view_restriction, child_object_map = _copy(
                original_restriction,
                exclude_fields=["id"],
                update_attrs={"page": translation_page},
            )
            view_restriction.save()
        else:
            # if both exist, sync them
            translation_restriction = translation_page.view_restrictions.first()
            should_save = False
            if (
                translation_restriction.restriction_type
                != original_restriction.restriction_type
            ):
                translation_restriction.restriction_type = (
                    original_restriction.restriction_type
                )
                should_save = True
            if translation_restriction.password != original_restriction.password:
                translation_restriction.password = original_restriction.password
                should_save = True
            if list(
                original_restriction.groups.values_list("pk", flat=True)
            ) != list(translation_restriction.groups.values_list("pk", flat=True)):
                translation_restriction.groups.set(
                    original_restriction.groups.all()
                )

            if should_save:
                translation_restriction.save()

    elif translation_page.view_restrictions.exists():
        # the original no longer has the restriction, so drop it
        translation_page.view_restrictions.all().delete()

@transaction.atomic
def update_from_db(self):
    """
    Retrieves the source instance from the database and updates this TranslationSource
    with its current contents.

    Raises:
        Model.DoesNotExist: If the source instance has been deleted.
    """
    instance = self.get_source_instance()

    if isinstance(instance, ClusterableModel):
        self.content_json = instance.to_json()
    else:
        serializable_data = get_serializable_data_for_fields(instance)
        self.content_json = json.dumps(serializable_data, cls=DjangoJSONEncoder)

    self.schema_version = get_schema_version(instance._meta.app_label) or ""
    self.object_repr = str(instance)[:200]
    self.last_updated_at = timezone.now()

    self.save(
        update_fields=[
            "content_json",
            "schema_version",
            "object_repr",
            "last_updated_at",
        ]
    )
    self.refresh_segments()

@classmethod
def update_or_create_from_instance(cls, instance):
    """
    Creates or updates a TranslationSource for the given instance.

    This extracts the content from the given instance. Then stores it in a new TranslationSource instance if one
    doesn't already exist. If one does already exist, it updates the existing TranslationSource.

    Args:
        instance (Model that inherits TranslatableMixin): A Translatable model instance to extract source content
            from.

    Returns:
        tuple[TranslationSource, boolean]: A two-tuple, the first component is the TranslationSource object, and
            the second component is a boolean that is True if the TranslationSource was created.
    """
    # Make sure we're using the specific version of pages
    if isinstance(instance, Page):
        instance = instance.specific

    object, created = TranslatableObject.objects.get_or_create_from_instance(
        instance
    )

    if isinstance(instance, ClusterableModel):
        content_json = instance.to_json()
    else:
        serializable_data = get_serializable_data_for_fields(instance)
        content_json = json.dumps(serializable_data, cls=DjangoJSONEncoder)

    # Check if the instance has changed since the previous version
    source = TranslationSource.objects.filter(
        object_id=object.translation_key, locale_id=instance.locale_id
    ).first()

    # Check if the instance has changed at all since the previous version
    if source:
        if json.loads(content_json) == json.loads(source.content_json):
            return source, False

    source, created = cls.objects.update_or_create(
        object=object,
        locale=instance.locale,
        # You can't update the content type of a source. So if this happens,
        # it'll try and create a new source and crash (can't have more than
        # one source per object/locale)
        specific_content_type=ContentType.objects.get_for_model(instance.__class__),
        defaults={
            "locale": instance.locale,
            "object_repr": str(instance)[:200],
            "content_json": content_json,
            "schema_version": get_schema_version(instance._meta.app_label) or "",
            "last_updated_at": timezone.now(),
        },
    )
    source.refresh_segments()
    return source, created

def update_target_view_restrictions(self, locale):
    """
    Creates a corresponding view restriction object for the translated page for the given locale

    Args:
        locale (Locale): The target locale
    """
    original = self.as_instance()

    # Only update restrictions for pages
    if not isinstance(original, Page):
        return

    try:
        translation_page = self.get_translated_instance(locale)
    except Page.DoesNotExist:
        return

    self.sync_view_restrictions(original, translation_page)