from django.conf import settings from django.contrib.auth.models import AnonymousUser from django.core.exceptions import ImproperlyConfigured, ValidationError from django.db import IntegrityError, models, transaction from django.db.models import Max from jsonfield import JSONField from openslides.agenda.mixins import AgendaItemWithListOfSpeakersMixin from openslides.core.config import config from openslides.core.models import Tag from openslides.mediafiles.models import Mediafile from openslides.poll.models import ( BaseOption, BasePoll, BaseVote, CollectDefaultVotesMixin, ) from openslides.utils.autoupdate import inform_changed_data from openslides.utils.exceptions import OpenSlidesError from openslides.utils.models import RESTModelMixin from ..utils.models import CASCADE_AND_AUTOUPDATE, SET_NULL_AND_AUTOUPDATE from .access_permissions import ( CategoryAccessPermissions, MotionAccessPermissions, MotionBlockAccessPermissions, MotionChangeRecommendationAccessPermissions, MotionCommentSectionAccessPermissions, StateAccessPermissions, StatuteParagraphAccessPermissions, WorkflowAccessPermissions, ) from .exceptions import WorkflowError class StatuteParagraph(RESTModelMixin, models.Model): """ Model for parts of the statute """ access_permissions = StatuteParagraphAccessPermissions() title = models.CharField(max_length=255) """Title of the statute paragraph.""" text = models.TextField() """Content of the statute paragraph.""" weight = models.IntegerField(default=10000) """ A weight field to sort statute paragraphs. """ class Meta: default_permissions = () ordering = ["weight", "title"] def __str__(self): return self.title class MotionManager(models.Manager): """ Customized model manager to support our get_full_queryset method. """ def get_full_queryset(self): """ Returns the normal queryset with all motions. In the background we join and prefetch all related models. """ return ( self.get_queryset() .select_related("state") .prefetch_related( "state__workflow", "comments", "comments__section", "comments__section__read_groups", "agenda_items", "lists_of_speakers", "polls", "attachments", "tags", "submitters", "supporters", "change_recommendations", ) ) class Motion(RESTModelMixin, AgendaItemWithListOfSpeakersMixin, models.Model): """ Model for motions. This class is the main entry point to all other classes related to a motion. """ access_permissions = MotionAccessPermissions() can_see_permission = "motions.can_see" objects = MotionManager() title = models.CharField(max_length=255) """The title of a motion.""" text = models.TextField() """The text of a motion.""" amendment_paragraphs = JSONField(null=True) """ If paragraph-based, diff-enabled amendment style is used, this field stores an array of strings or null values. Each entry corresponds to a paragraph of the text of the original motion. If the entry is null, then the paragraph remains unchanged. If the entry is a string, this is the new text of the paragraph. amendment_paragraphs and text are mutually exclusive. """ modified_final_version = models.TextField(null=True, blank=True) """A field to copy in the final version of the motion and edit it there.""" reason = models.TextField(null=True, blank=True) """The reason for a motion.""" state = models.ForeignKey( "State", related_name="+", on_delete=models.PROTECT, # Do not let the user delete states, that are used for motions null=True, ) # TODO: Check whether null=True is necessary. """ The related state object. This attribute is to get the current state of the motion. """ state_extension = models.TextField(blank=True, null=True) """ A text field fo additional information about the state. """ recommendation = models.ForeignKey( "State", related_name="+", on_delete=SET_NULL_AND_AUTOUPDATE, null=True ) """ The recommendation of a person or committee for this motion. """ recommendation_extension = models.TextField(blank=True, null=True) """ A text field fo additional information about the recommendation. """ identifier = models.CharField(max_length=255, null=True, blank=True, unique=True) """ A string as human readable identifier for the motion. """ identifier_number = models.IntegerField(null=True) """ Counts the number of the motion in one category. Needed to find the next free motion identifier. """ weight = models.IntegerField(default=10000) """ A weight field to sort motions. """ sort_parent = models.ForeignKey( "self", on_delete=SET_NULL_AND_AUTOUPDATE, null=True, blank=True, related_name="children", ) """ A parent field for multi-depth sorting of motions. """ category = models.ForeignKey( "Category", on_delete=SET_NULL_AND_AUTOUPDATE, null=True, blank=True ) """ ForeignKey to one category of motions. """ category_weight = models.IntegerField(default=10000) """ Sorts the motions inside a category. Default is 10000 so new motions in a category will be added on the end of the list. """ motion_block = models.ForeignKey( "MotionBlock", on_delete=SET_NULL_AND_AUTOUPDATE, null=True, blank=True ) """ ForeignKey to one block of motions. """ origin = models.CharField(max_length=255, blank=True) """ A string to describe the origin of this motion e. g. that it was discussed at another assembly/conference. """ attachments = models.ManyToManyField(Mediafile, blank=True) """ Many to many relation to mediafile objects. """ parent = models.ForeignKey( "self", on_delete=SET_NULL_AND_AUTOUPDATE, null=True, blank=True, related_name="amendments", ) """ Field for amendments to reference to the motion that should be altered. Null if the motion is not an amendment. """ statute_paragraph = models.ForeignKey( StatuteParagraph, on_delete=SET_NULL_AND_AUTOUPDATE, null=True, blank=True, related_name="motions", ) """ Field to reference to a statute paragraph if this motion is a statute-amendment. Null if the motion is not a statute-amendment. """ tags = models.ManyToManyField(Tag, blank=True) """ Tags to categorise motions. """ supporters = models.ManyToManyField( settings.AUTH_USER_MODEL, related_name="motion_supporters", blank=True ) """ Users who support this motion. """ created = models.DateTimeField(auto_now_add=True) """ Timestamp when motion is created. """ last_modified = models.DateTimeField(auto_now=True) """ Timestamp when motion is modified. """ class Meta: default_permissions = () permissions = ( ("can_see", "Can see motions"), ("can_see_internal", "Can see motions in internal state"), ("can_create", "Can create motions"), ("can_create_amendments", "Can create amendments"), ("can_support", "Can support motions"), ("can_manage_metadata", "Can manage motion metadata"), ("can_manage", "Can manage motions"), ) ordering = ("identifier",) verbose_name = "Motion" def __str__(self): """ Return the title of this motion. """ return self.title # TODO: Use transaction def save(self, skip_autoupdate=False, *args, **kwargs): """ Save the motion. 1. Set the state of a new motion to the default state. 2. Ensure that the identifier is not an empty string. 3. Save the motion object. """ if not self.state: self.reset_state() # Solves the problem, that there can only be one motion with an empty # string as identifier. if not self.identifier and isinstance(self.identifier, str): self.identifier = None # Try to save the motion until it succeeds with a correct identifier. while True: try: # Always skip autoupdate. Maybe we run it later in this method. with transaction.atomic(): super(Motion, self).save( # type: ignore skip_autoupdate=True, *args, **kwargs ) except IntegrityError: # Identifier is already used. if hasattr(self, "_identifier_prefix"): # Calculate a new one and try again. self.identifier_number, self.identifier = self.increment_identifier_number( self.identifier_number, self._identifier_prefix ) else: # Do not calculate a new one but reraise the IntegrityError. # The error is caught in the category sort view. raise else: # Save was successful. End loop. break if not skip_autoupdate: inform_changed_data(self) def set_identifier(self): """ Sets the motion identifier automaticly according to the config value if it is not set yet. """ # The identifier is already set or should be set manually. if config["motions_identifier"] == "manually" or self.identifier: # Do not set an identifier. return # If config 'motions_identifier_with_blank' is set, use blanks when building identifier. with_blank = config["motions_identifier_with_blank"] # Build prefix. if self.is_amendment(): parent_identifier = self.parent.identifier or "" if with_blank: prefix = f"{parent_identifier} {config['motions_amendments_prefix']}" else: prefix = f"{parent_identifier}{config['motions_amendments_prefix']}" elif self.category is None or not self.category.prefix: prefix = "" else: if with_blank: prefix = f"{self.category.prefix} " else: prefix = self.category.prefix self._identifier_prefix = prefix # Use the already assigned identifier_number, if the motion has one. # Else get the biggest number. if self.identifier_number is not None: number = self.identifier_number initial_increment = False else: # Find all motions that should be included in the calculations. if self.is_amendment(): motions = self.parent.amendments.all() # The motions should be counted per category. elif config["motions_identifier"] == "per_category": motions = Motion.objects.filter(category=self.category) # The motions should be counted over all. else: motions = Motion.objects.all() number = ( motions.aggregate(Max("identifier_number"))["identifier_number__max"] or 0 ) initial_increment = True # Calculate new identifier. number, identifier = self.increment_identifier_number( number, prefix, initial_increment=initial_increment ) # Set identifier and identifier_number. self.identifier = identifier self.identifier_number = number def increment_identifier_number(self, number, prefix, initial_increment=True): """ Helper method. It increments the number until a free identifier number is found. Returns new number and identifier. """ if initial_increment: number += 1 identifier = f"{prefix}{Motion.extend_identifier_number(number)}" while Motion.objects.filter(identifier=identifier).exists(): number += 1 identifier = f"{prefix}{Motion.extend_identifier_number(number)}" return number, identifier @classmethod def extend_identifier_number(cls, number): """ Returns the number used in the set_identifier method with leading zero charaters according to the config value. """ result = str(number) if config["motions_identifier_min_digits"]: if not isinstance(config["motions_identifier_min_digits"], int): raise ImproperlyConfigured( "Config value 'motions_identifier_min_digits' must be an integer." ) result = ( "0" * (config["motions_identifier_min_digits"] - len(str(number))) + result ) return result def is_submitter(self, user): """ Returns True if user is a submitter of this motion, else False. """ return self.submitters.filter(user=user).exists() def is_supporter(self, user): """ Returns True if user is a supporter of this motion, else False. """ return user in self.supporters.all() def create_poll(self, skip_autoupdate=False): """ Create a new poll for this motion. Return the new poll object. """ if self.state.allow_create_poll: poll = MotionPoll(motion=self) poll.save(skip_autoupdate=skip_autoupdate) poll.set_options(skip_autoupdate=skip_autoupdate) return poll else: raise WorkflowError( f"You can not create a poll in state {self.state.name}." ) @property def workflow_id(self): """ Returns the id of the workflow of the motion. """ return self.state.workflow.pk def set_state(self, state): """ Set the state of the motion. 'state' can be the id of a state object or a state object. """ if isinstance(state, int): state = State.objects.get(pk=state) if not state.dont_set_identifier: self.set_identifier() self.state = state def reset_state(self, workflow=None): """ Set the state to the default state. If an identifier was set automatically, reset the identifier and identifier_number. 'workflow' can be a workflow, an id of a workflow or None. If the motion is new and workflow is None, it chooses the default workflow from config. """ if isinstance(workflow, int): workflow = Workflow.objects.get(pk=workflow) if workflow is not None: new_state = workflow.first_state elif self.state: new_state = self.state.workflow.first_state else: new_state = ( Workflow.objects.get(pk=config["motions_workflow"]).first_state or Workflow.objects.get(pk=config["motions_workflow"]).states.all()[0] ) self.set_state(new_state) def set_recommendation(self, recommendation): """ Set the recommendation of the motion. 'recommendation' can be the id of a state object or a state object. """ if isinstance(recommendation, int): recommendation = State.objects.get(pk=recommendation) self.recommendation = recommendation def follow_recommendation(self): """ Set the state of this motion to its recommendation. """ if self.recommendation is not None: self.set_state(self.recommendation) if ( self.recommendation_extension is not None and self.state.show_state_extension_field and self.recommendation.show_recommendation_extension_field ): self.state_extension = self.recommendation_extension def get_title_information(self): return {"title": self.title, "identifier": self.identifier} def is_amendment(self): """ Returns True if the motion is an amendment. A motion is a amendment if amendments are activated in the config and the motion has a parent. """ return config["motions_amendments_enabled"] and self.parent is not None def is_paragraph_based_amendment(self): """ Returns True if the motion is an amendment that stores the changes on a per-paragraph-basis and is therefore eligible to be shown in diff-view. """ return self.is_amendment() and self.amendment_paragraphs def get_paragraph_based_amendments(self): """ Returns a list of all paragraph-based amendments to this motion """ return list( filter( lambda amend: amend.is_paragraph_based_amendment(), self.amendments.all(), ) ) @property def amendment_level(self): """ Returns the amount of parent motions. """ if self.parent is None: return 0 else: return self.parent.amendment_level + 1 class MotionCommentSection(RESTModelMixin, models.Model): """ The model for comment sections for motions. Each comment is related to one section, so each motions has the ability to have comments from the same section. """ access_permissions = MotionCommentSectionAccessPermissions() name = models.CharField(max_length=255) """ The name of the section. """ read_groups = models.ManyToManyField( settings.AUTH_GROUP_MODEL, blank=True, related_name="read_comments" ) """ These groups have read-access to the section. """ write_groups = models.ManyToManyField( settings.AUTH_GROUP_MODEL, blank=True, related_name="write_comments" ) """ These groups have write-access to the section. """ weight = models.IntegerField(default=10000) """ To sort comment sections. """ class Meta: default_permissions = () class MotionComment(RESTModelMixin, models.Model): """ Represents a motion comment. A comment is always related to a motion and a comment section. The section determinates the title of the category. """ comment = models.TextField() """ The comment. """ motion = models.ForeignKey( Motion, on_delete=models.CASCADE, related_name="comments" ) """ The motion where this comment belongs to. """ section = models.ForeignKey( MotionCommentSection, on_delete=models.PROTECT, related_name="comments" ) """ The section of the comment. """ class Meta: default_permissions = () unique_together = ("motion", "section") def get_root_rest_element(self): """ Returns the motion to this instance which is the root REST element. """ return self.motion class SubmitterManager(models.Manager): """ Manager for Submitter model. Provides a customized add method. """ def add(self, user, motion, skip_autoupdate=False): """ Customized manager method to prevent anonymous users to be a submitter and that someone is not twice a submitter. Cares also for the initial sorting of the submitters. """ if self.filter(user=user, motion=motion).exists(): raise OpenSlidesError(f"{user} is already a submitter.") if isinstance(user, AnonymousUser): raise OpenSlidesError("An anonymous user can not be a submitter.") weight = ( self.filter(motion=motion).aggregate(models.Max("weight"))["weight__max"] or 0 ) submitter = self.model(user=user, motion=motion, weight=weight + 1) submitter.save(force_insert=True, skip_autoupdate=skip_autoupdate) return submitter class Submitter(RESTModelMixin, models.Model): """ M2M Model for submitters. """ objects = SubmitterManager() """ Use custom Manager. """ user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=CASCADE_AND_AUTOUPDATE) """ ForeignKey to the user who is the submitter. """ motion = models.ForeignKey( Motion, on_delete=models.CASCADE, related_name="submitters" ) """ ForeignKey to the motion. """ weight = models.IntegerField(null=True) class Meta: default_permissions = () def __str__(self): return str(self.user) def get_root_rest_element(self): """ Returns the motion to this instance which is the root REST element. """ return self.motion class MotionChangeRecommendationManager(models.Manager): """ Customized model manager to support our get_full_queryset method. """ def get_full_queryset(self): """ Returns the normal queryset with all change recommendations. In the background we join and prefetch all related models. """ return self.get_queryset() class MotionChangeRecommendation(RESTModelMixin, models.Model): """ A MotionChangeRecommendation object saves change recommendations for a specific Motion """ access_permissions = MotionChangeRecommendationAccessPermissions() objects = MotionChangeRecommendationManager() motion = models.ForeignKey( Motion, on_delete=CASCADE_AND_AUTOUPDATE, related_name="change_recommendations" ) """The motion to which the change recommendation belongs.""" rejected = models.BooleanField(default=False) """If true, this change recommendation has been rejected""" internal = models.BooleanField(default=False) """If true, this change recommendation can not be seen by regular users""" type = models.PositiveIntegerField(default=0) """Replacement (0), Insertion (1), Deletion (2), Other (3)""" other_description = models.TextField(blank=True) """The description text for type 'other'""" line_from = models.PositiveIntegerField() """The number or the first affected line""" line_to = models.PositiveIntegerField() """The number or the last affected line (inclusive)""" text = models.TextField(blank=True) """The replacement for the section of the original text specified by motion, line_from and line_to""" author = models.ForeignKey( settings.AUTH_USER_MODEL, on_delete=SET_NULL_AND_AUTOUPDATE, null=True ) """A user object, who created this change recommendation. Optional.""" creation_time = models.DateTimeField(auto_now=True) """Time when the change recommendation was saved.""" class Meta: default_permissions = () def __str__(self): """Return a string, representing this object.""" return f"Recommendation for Motion {self.motion_id}, line {self.line_from} - {self.line_to}" def collides_with_other_recommendation(self, recommendations): for recommendation in recommendations: if not ( self.line_from < recommendation.line_from and self.line_to <= recommendation.line_from ) and not ( self.line_from >= recommendation.line_to and self.line_to > recommendation.line_to ): return True return False def save(self, *args, **kwargs): recommendations = MotionChangeRecommendation.objects.filter( motion=self.motion ).exclude(pk=self.pk) if self.collides_with_other_recommendation(recommendations): raise ValidationError( f"The recommendation collides with an existing one (line {self.line_from} - {self.line_to})." ) result = super().save(*args, **kwargs) # Hotfix for #4491: Trigger extra autoupdate for motion so that the serializer # field vor motion change recommendations gets updated too. inform_changed_data(self.motion) return result def delete(self, *args, **kwargs): # Hotfix for #4491: Trigger extra autoupdate for motion so that the serializer # field vor motion change recommendations gets updated too. motion = self.motion result = super().delete(*args, **kwargs) inform_changed_data(motion) return result class Category(RESTModelMixin, models.Model): """ Model for categories of motions. """ access_permissions = CategoryAccessPermissions() name = models.CharField(max_length=255) """Name of the category.""" prefix = models.CharField(blank=True, max_length=32) """ Prefix of the category. Used to build the identifier of a motion. """ parent = models.ForeignKey( "self", on_delete=CASCADE_AND_AUTOUPDATE, null=True, blank=True, related_name="children", ) weight = models.IntegerField(default=10000) class Meta: default_permissions = () ordering = ["weight"] def __str__(self): if self.prefix: return f"{self.prefix} - {self.name}" else: return self.name @property def level(self): """ Returns the level in the tree of categories. Level 0 means this item is a root item in the tree. Level 1 indicates that the parent is a root item, level 2 that the parent's parent is a root item and so on. Attention! This executes one query for each ancestor of the category. """ if self.parent is None: return 0 else: return self.parent.level + 1 class MotionBlockManager(models.Manager): """ Customized model manager to support our get_full_queryset method. """ def get_full_queryset(self): """ Returns the normal queryset with all motion blocks. In the background the related agenda item is prefetched from the database. """ return self.get_queryset().prefetch_related("agenda_items", "lists_of_speakers") class MotionBlock(RESTModelMixin, AgendaItemWithListOfSpeakersMixin, models.Model): """ Model for blocks of motions. """ access_permissions = MotionBlockAccessPermissions() objects = MotionBlockManager() title = models.CharField(max_length=255) internal = models.BooleanField(default=False) """ If a motion block is internal, only users with `motions.can_manage` can see and manage these blocks. """ class Meta: verbose_name = "Motion block" default_permissions = () def __str__(self): return self.title def get_title_information(self): return {"title": self.title} class MotionVote(RESTModelMixin, BaseVote): """Saves the votes for a MotionPoll. There should allways be three MotionVote objects for each poll, one for 'yes', 'no', and 'abstain'.""" option = models.ForeignKey("MotionOption", on_delete=models.CASCADE) """The option object, to witch the vote belongs.""" class Meta: default_permissions = () def get_root_rest_element(self): """ Returns the motion to this instance which is the root REST element. """ return self.option.poll.motion class MotionOption(RESTModelMixin, BaseOption): """Links between the MotionPollClass and the MotionVoteClass. There should be one MotionOption object for each poll.""" poll = models.ForeignKey("MotionPoll", on_delete=models.CASCADE) """The poll object, to witch the object belongs.""" vote_class = MotionVote """The VoteClass, to witch this Class links.""" class Meta: default_permissions = () def get_root_rest_element(self): """ Returns the motion to this instance which is the root REST element. """ return self.poll.motion # TODO: remove the type-ignoring in the next line, after this is solved: # https://github.com/python/mypy/issues/3855 class MotionPoll(RESTModelMixin, CollectDefaultVotesMixin, BasePoll): # type: ignore """The Class to saves the vote result for a motion poll.""" motion = models.ForeignKey(Motion, on_delete=models.CASCADE, related_name="polls") """The motion to witch the object belongs.""" option_class = MotionOption """The option class, witch links between this object the the votes.""" vote_values = ["Yes", "No", "Abstain"] """The possible anwers for the poll. 'Yes, 'No' and 'Abstain'.""" class Meta: default_permissions = () def __str__(self): """ Representation method only for debugging purposes. """ return f"MotionPoll for motion {self.motion}" def set_options(self, skip_autoupdate=False): """Create the option class for this poll.""" # TODO: maybe it is possible with .create() to call this without poll=self # or call this in save() self.get_option_class()(poll=self).save(skip_autoupdate=skip_autoupdate) def get_percent_base_choice(self): return config["motions_poll_100_percent_base"] def get_root_rest_element(self): """ Returns the motion to this instance which is the root REST element. """ return self.motion class State(RESTModelMixin, models.Model): """ Defines a state for a motion. Every state belongs to a workflow. All states of a workflow are linked together via 'next_states'. One of these states is the first state, but this is saved in the workflow table (one-to-one relation). In every state you can configure some handling of a motion. See the following fields for more information. Additionally every motion can refer to one state as recommendation of an person or committee (see config 'motions_recommendations_by'). This means that the person or committee recommends to set the motion to this state. """ access_permissions = StateAccessPermissions() name = models.CharField(max_length=255) """A string representing the state.""" recommendation_label = models.CharField(max_length=255, null=True) """A string for a recommendation to set the motion to this state.""" workflow = models.ForeignKey( "Workflow", on_delete=models.CASCADE, related_name="states" ) """A many-to-one relation to a workflow.""" next_states = models.ManyToManyField("self", symmetrical=False, blank=True) """A many-to-many relation to all states, that can be choosen from this state.""" css_class = models.CharField(max_length=255, default="lightblue") """ A css class string for showing the state name in a coloured label. Currently supported values are grey, red, green, lightblue and yellow. The default is lightblue. """ restriction = JSONField(default=list) """ Defines which users may see motions in this state: Contains a list of one or more of the following strings: * motions.can_see_internal * motions.can_manage_metadata * motions.can_manage * is_submitter If the list is empty, everybody with the general permission to see motions can see this motion. If the list contains at least one item, the user needs the permission (or have the attribute) for at least one of the restrictions. Default: Empty list so everybody can see the motion. """ allow_support = models.BooleanField(default=False) """If true, persons can support the motion in this state.""" allow_create_poll = models.BooleanField(default=False) """If true, polls can be created in this state.""" allow_submitter_edit = models.BooleanField(default=False) """If true, the submitter can edit the motion in this state.""" dont_set_identifier = models.BooleanField(default=False) """ Decides if the motion gets an identifier. If true, the motion does not get an identifier if the state change to this one, else it does. """ show_state_extension_field = models.BooleanField(default=False) """ If true, an additional input field (from motion comment) is visible to extend the state name. The full state name is composed of the given state name and the entered value of this input field. """ merge_amendment_into_final = models.SmallIntegerField(default=0) """ Relevant for amendments: 1: Amendments of this status or recommendation will be merged into the final version of the motion. 0: Undefined. -1: Amendments of this status or recommendation will not be merged into the final version of the motion. (Hint: The status field takes precedence. That means, if status is 1 or -1, this is the final decision. The recommendation only is considered if the status is 0) """ show_recommendation_extension_field = models.BooleanField(default=False) """ If true, an additional input field (from motion comment) is visible to extend the recommendation label. The full recommendation string is composed of the given recommendation label and the entered value of this input field. """ class Meta: default_permissions = () def __str__(self): """Returns the name of the state.""" return self.name def save(self, **kwargs): """Saves a state in the database. Used to check the integrity before saving. Also used to check that recommendation_label is not an empty string. """ self.check_next_states() if self.recommendation_label == "": raise WorkflowError( f"The field recommendation_label of {self} must not " "be an empty string." ) super(State, self).save(**kwargs) def check_next_states(self): """Checks whether all next states of a state belong to the correct workflow.""" # No check if it is a new state which has not been saved yet. if not self.id: return for state in self.next_states.all(): if not state.workflow == self.workflow: raise WorkflowError( f"{state} can not be next state of {self} because it does not belong to the same workflow." ) def is_next_or_previous_state_id(self, state_id): """ Returns true, if the given state id is a valid next or previous state """ next_state_ids = [item.id for item in self.next_states.all()] previous_state_ids = [ item.id for item in State.objects.filter(next_states__in=[self.id]) ] return state_id in next_state_ids or state_id in previous_state_ids class WorkflowManager(models.Manager): """ Customized model manager to support our get_full_queryset method. """ def get_full_queryset(self): """ Returns the normal queryset with all workflows. In the background the first state is joined and all states and next states are prefetched from the database. """ return ( self.get_queryset() .select_related("first_state") .prefetch_related("states", "states__next_states") ) class Workflow(RESTModelMixin, models.Model): """ Defines a workflow for a motion. """ access_permissions = WorkflowAccessPermissions() objects = WorkflowManager() name = models.CharField(max_length=255) """A string representing the workflow.""" first_state = models.OneToOneField( State, on_delete=models.CASCADE, related_name="+", null=True ) """A one-to-one relation to a state, the starting point for the workflow.""" class Meta: default_permissions = () def __str__(self): """Returns the name of the workflow.""" return self.name def save(self, **kwargs): """Saves a workflow in the database. Used to check the integrity before saving. """ self.check_first_state() super(Workflow, self).save(**kwargs) def check_first_state(self): """Checks whether the first_state itself belongs to the workflow.""" if self.first_state and not self.first_state.workflow == self: raise WorkflowError( f"{self.first_state} can not be first state of {self} because it " "does not belong to it." )