app/soc/logic/models/student_proposal.py
author Daniel Hans <Daniel.M.Hans@gmail.com>
Fri, 07 Aug 2009 01:27:24 +0200
changeset 2736 8f3935f0f4ba
parent 2198 95ac403c6dd4
permissions -rw-r--r--
Argument store added to updateEntityProperties. This argument determines if an entity should be stored in the data model after its properties are updated. It may be useful, for example, along with tasks (Task Queue API). One may want to make some modifications to an entity during execution of a task, but the developer is sure that at least one new task, which also wants to modify the entity, will be queued, so he or she can just update the entity without saving the changes to the data model, set the entity in memcache and the following task (which is to be executed very shortly) is to retrive the current entity from the memcache (without any expensive calls to the actual data model).

#!/usr/bin/python2.5
#
# Copyright 2009 the Melange authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Student Proposal (Model) query functions.
"""

__authors__ = [
  '"Lennard de Rijk" <ljvderijk@gmail.com>',
  ]


from soc.logic.models import base
from soc.logic.models import student as student_logic
from soc.models import student_proposal

import soc.models.linkable
import soc.models.student_proposal


class Logic(base.Logic):
  """Logic methods for the Student Proposal model.
  """

  def __init__(self, model=soc.models.student_proposal.StudentProposal,
               base_model=soc.models.linkable.Linkable, 
               scope_logic=student_logic):
    """Defines the name, key_name and model for this entity.
    """

    super(Logic, self).__init__(model=model, base_model=base_model,
                                scope_logic=scope_logic)


  def getRankerFor(self, entity):
    """Returns the ranker for the given Student Proposal.

    Args:
      entity: Student Proposal entity for which the ranker should be returned

    Returns:
      Ranker object which is used to rank the given entity
    """

    from soc.logic.models.ranker_root import logic as ranker_root_logic

    fields = {'link_id': student_proposal.DEF_RANKER_NAME,
        'scope': entity.org}

    ranker_root = ranker_root_logic.getForFields(fields, unique=True)
    ranker = ranker_root_logic.getRootFromEntity(ranker_root)

    return ranker

  def getProposalsToBeAcceptedForOrg(self, org_entity, step_size=25):
    """Returns all StudentProposals which will be accepted into the program
    for the given organization.

    params:
      org_entity: the Organization for which the proposals should be checked
      step_size: optional parameter to specify the amount of Student Proposals
                that should be retrieved per roundtrip to the datastore

    returns:
      List with all StudentProposal which will be accepted into the program
    """

    # check if there are already slots taken by this org
    fields = {'org': org_entity,
              'status': 'accepted'}

    query = self.getQueryForFields(fields)

    slots_left_to_assign = max(0, org_entity.slots - query.count())

    if slots_left_to_assign == 0:
      # no slots left so return nothing
      return []

    fields = {'org': org_entity,
              'status': 'pending'}
    order = ['-score']

    # get the the number of proposals that would be assigned a slot
    query = self.getQueryForFields(
        fields, order=order)

    proposals = query.fetch(slots_left_to_assign)
    proposals = [i for i in proposals if i.mentor]

    offset = slots_left_to_assign

    # retrieve as many additional proposals as needed in case the top
    # N do not have a mentor assigned
    while len(proposals) < slots_left_to_assign:
      new_proposals = query.fetch(step_size, offset=offset)

      if not new_proposals:
        # we ran out of proposals`
        break

      new_proposals = [i for i in new_proposals if i.mentor]
      proposals += new_proposals
      offset += step_size

    # cut off any superfluous proposals
    return proposals[:slots_left_to_assign]

  def _onCreate(self, entity):
    """Adds this proposal to the organization ranker entity.
    """

    ranker = self.getRankerFor(entity)
    ranker.SetScore(entity.key().id_or_name(), [entity.score])

    super(Logic, self)._onCreate(entity)

  def _updateField(self, entity, entity_properties, name):
    """Called when the fields of the student_proposal are updated.

      - Update the ranker if the score changes and keep the score within bounds
      - Remove the entity from the ranker when the status changes to invalid or rejected
    """

    value = entity_properties[name]

    if name == 'score':
      # keep the score within bounds
      min_score, max_score = student_proposal.DEF_SCORE

      value = max(min_score, min(value, max_score-1))
      entity_properties[name] = value

      # update the ranker
      ranker = self.getRankerFor(entity)
      ranker.SetScore(entity.key().id_or_name(), [value])

    if name == 'status':

      if value in ['invalid', 'rejected'] and entity.status != value:
        # the proposal is going into invalid or rejected state
        # remove the score from the ranker
        ranker = self.getRankerFor(entity)

        # entries in the ranker can be removed by setting the score to None
        ranker.SetScore(entity.key().id_or_name(), None)

    return super(Logic, self)._updateField(entity, entity_properties, name)

  def delete(self, entity):
    """Removes Ranker entry and all ReviewFollowers before deleting the entity.

    Args:
      entity: an existing entity in datastore
    """

    from soc.logic.models.review_follower import logic as review_follower_logic

    # entries in the ranker can be removed by setting the score to None
    ranker = self.getRankerFor(entity)
    ranker.SetScore(entity.key().id_or_name(), None)

    # get all the ReviewFollwers that have this entity as it's scope
    fields = {'scope': entity}

    # TODO be sure that this captures all the followers
    followers = review_follower_logic.getForFields(fields)

    for follower in followers:
      review_follower_logic.delete(follower)

    # call to super to complete the deletion
    super(Logic, self).delete(entity)


logic = Logic()