Django 1.9.5 : 역방향 조회 필드의 FieldError 때때로

Question

장고에서 장황한 오류가 발생하여 objects.all()을 실행하려고 시도 할 때 Queryset을 프리 페칭합니다. model._meta에서 때때로 쿼리 세트의 인스턴스 생성과 반복을 통해 필드가 누락 된 것으로 보이는 문제가 있습니다. 마치 쿼리 세트의 프리 페치가 실제로 객체 목록의 반복에 맞춰 실행되지 않는 것과 같습니다.

이 예제에서 data.service_log는 단순히 servicelog이라는 프리 페치 항목이있는 쿼리 세트입니다. 셸에서 쿼리 세트를 실행할 때 쿼리 세트에서 self.names_to_path(lookup_splitted, self.get_meta()) 메서드의 모든 필드를 볼 수 있습니다. 그들은 모두 거기에 있습니다, 특히 "servicelog".

이 오류에 대한 추적에는 "servicelog"가 사용 가능한 필드가 아니라고 선택할 수있는 필드 목록에 나열되어 있다고 표시되어 있습니다. 이것은 장고 버그 인 것 같지만 행동을 설명하거나 분리 할 수 ​​없기 때문에 확신 할 수 없습니다. 나는이 오류를 얻는 유일한 사람이 될 수 없습니다. names_to_paths() 방법에서는 django/db/models/sql/query.py 인 것으로 보입니다. 여기에 해결하기 위해 실패 코드는 다음과 같습니다

query.py names_to_paths(): 

field = None 
try: 
    field = opts.get_field(name) 
except FieldDoesNotExist: 
    if name in self.annotation_select: 
     field = self.annotation_select[name].output_field 

if field is not None: 
    # Fields that contain one-to-many relations with a generic 
    # model (like a GenericForeignKey) cannot generate reverse 
    # relations and therefore cannot be used for reverse querying. 
    if field.is_relation and not field.related_model: 
     raise FieldError(
      "Field %r does not generate an automatic reverse " 
      "relation and therefore cannot be used for reverse " 
      "querying. If it is a GenericForeignKey, consider " 
      "adding a GenericRelation." % name 
     ) 
    try: 
     model = field.model._meta.concrete_model 
    except AttributeError: 
     model = None 
else: 
    # We didn't find the current field, so move position back 
    # one step. 
    pos -= 1 
    if pos == -1 or fail_on_missing: 
     field_names = list(get_field_names_from_opts(opts)) 
     available = sorted(field_names + list(self.annotation_select)) 
     raise FieldError("Cannot resolve keyword %r into field. " 
         "Choices are: %s" % (name, ", .join(available))) 
    break 

field does not get set in the first try, then the condition statement 필드가 다른 것도 fails so we enter theblock. There the POS gets reduced by one, but since this field is 'servicelog' it is already at 0. However, when I try this in the shell, it always finds the 필드 with opts.get_field ('servicelog') '하지 않는 경우. WSGI와 Apache2에서 실행될 때만이 오류가 발생합니다. 다시 한번 말하지만, 모든 시간이 아니기 때문에 테스트하기가 매우 어렵습니다. 나는 이것에 당혹스럽고 어디서 단서를 찾을 지 확신하지 못한다. 아무도 탐험해야 할 것에 대한 아이디어가 없다면 너무 감사 할 것입니다.

Traceback (most recent call last): 

    File "/var/www/fast/services/views/edit.py", line 12897, in service_log 
    for service in data.service_log: 

    File "/usr/local/lib/python2.7/dist-packages/django/db/models/query.py", line 258, in __iter__ 
    self._fetch_all() 

    File "/usr/local/lib/python2.7/dist-packages/django/db/models/query.py", line 1076, in _fetch_all 
    self._prefetch_related_objects() 

    File "/usr/local/lib/python2.7/dist-packages/django/db/models/query.py", line 656, in _prefetch_related_objects 
    prefetch_related_objects(self._result_cache, self._prefetch_related_lookups) 

    File "/usr/local/lib/python2.7/dist-packages/django/db/models/query.py", line 1457, in prefetch_related_objects 
    obj_list, additional_lookups = prefetch_one_level(obj_list, prefetcher, lookup, level) 

    File "/usr/local/lib/python2.7/dist-packages/django/db/models/query.py", line 1556, in prefetch_one_level 
    prefetcher.get_prefetch_queryset(instances, lookup.get_current_queryset(level))) 

    File "/usr/local/lib/python2.7/dist-packages/django/db/models/fields/related_descriptors.py", line 802, in get_prefetch_queryset 
    queryset = queryset._next_is_sticky().filter(**query) 

    File "/usr/local/lib/python2.7/dist-packages/django/db/models/query.py", line 790, in filter 
    return self._filter_or_exclude(False, *args, **kwargs) 

    File "/usr/local/lib/python2.7/dist-packages/django/db/models/query.py", line 808, in _filter_or_exclude 
    clone.query.add_q(Q(*args, **kwargs)) 

    File "/usr/local/lib/python2.7/dist-packages/django/db/models/sql/query.py", line 1243, in add_q 
    clause, _ = self._add_q(q_object, self.used_aliases) 

    File "/usr/local/lib/python2.7/dist-packages/django/db/models/sql/query.py", line 1269, in _add_q 
    allow_joins=allow_joins, split_subq=split_subq, 

    File "/usr/local/lib/python2.7/dist-packages/django/db/models/sql/query.py", line 1149, in build_filter 
    lookups, parts, reffed_expression = self.solve_lookup_type(arg) 

    File "/usr/local/lib/python2.7/dist-packages/django/db/models/sql/query.py", line 1035, in solve_lookup_type 
    _, field, _, lookup_parts = self.names_to_path(lookup_splitted, self.get_meta()) 

    File "/usr/local/lib/python2.7/dist-packages/django/db/models/sql/query.py", line 1330, in names_to_path 
    "Choices are: %s" % (name, ", ".join(available))) 

FieldError: Cannot resolve keyword u'servicelog' into field. Choices are: additional_county_worker_notes, adoption_disrupted, adoption_first_name, adoption_last_name, adoption_middle_name, adoption_placement_date, adoption_placement_reason, adoption_placement_reason_id, adoption_placement_type, adoption_risk_level, adoption_risk_level_id, adoption_termination_date, adoption_termination_destination, adoption_termination_reason, adoption_termination_reason_id, adoptive_placement, agency, agency_id, all_items_outstanding, all_items_past_due, appeal_process_date, attached_file, attends_college, attorney_email_address, attorney_email_address_id, attorney_fax, attorney_fax_id, attorney_investigator_email_address, attorney_investigator_email_address_id, attorney_investigator_fax, attorney_investigator_fax_id, attorney_investigator_name, attorney_investigator_phone, attorney_investigator_phone_id, attorney_name, attorney_phone, attorney_phone_id, blood_related_to_applicants, blood_relationship, casa_email_address, casa_email_address_id, casa_fax, casa_fax_id, casa_name, casa_phone, casa_phone_id, certification_items_outstanding, certification_items_past_due, classification, classification_id, client, client_id, county_adoption_worker, county_adoption_worker_cell, county_adoption_worker_cell_id, county_adoption_worker_email_address, county_adoption_worker_email_address_id, county_adoption_worker_fax, county_adoption_worker_fax_id, county_adoption_worker_office, county_adoption_worker_office_id, county_adoption_worker_phone, county_adoption_worker_phone_id, county_adoption_worker_title, county_case_number, county_worker, county_worker_cell, county_worker_cell_id, county_worker_email_address, county_worker_email_address_id, county_worker_fax, county_worker_fax_id, county_worker_office, county_worker_office_id, county_worker_phone, county_worker_phone_id, county_worker_title, court, court_case_name, court_case_number, court_department, court_id, created, current_grade, date_identified_adoptive, date_placed_with_home, deleted, discharge_summary, eligibility_worker, eligibility_worker_email_address, eligibility_worker_email_address_id, eligibility_worker_phone, eligibility_worker_phone_id, emergency_placement, employed_80_hours, enable_discharge_summary, expected_type, expected_type_id, extended_family_contact_allowed, final_payment_amount, finalization_date, foreign_placement, hearing_36626_date, homestudy, id, incident_placement_1, incident_placement_2, incident_placement_3, incident_placement_4, individualized_plan_review, inhousemove, interpretive_summary, item_due, items_approved, items_pending, items_rejected, items_update_requested, la_county_id, medi_cal, medi_cal_eligibility_phone, medi_cal_eligibility_phone_id, medi_cal_eligibility_worker, medi_cal_id, modified, monthly_monitored_visit_hours, mother_child, move_in_type, move_out_type, new_protective_custody_petition, non_minor_dependent, non_truant, notes, number_of_files_required, other_school_contact, other_school_contact_first_name, other_school_contact_last_name, parent_payment_override_annually, parent_payment_override_daily, parent_payment_override_monthly, parental_contact_allowed, parental_group, parental_group_id, payment_amount, percent_certified, percent_items_complete, person_number, placement, placement_date, placement_id, placement_payment_override_annually, placement_payment_override_daily, placement_payment_override_monthly, placement_reason, placement_reason_details, placement_reason_id, placement_self, placer_shelter_bed, prior_placement, progress_summary, projected_adoption_36626_date, projected_adoption_finalization_date, projected_adoption_placement_date, recordreview, requires_educational_support, requires_mental_health_services, respite, school, school_different, school_id, school_liaison_email, school_liaison_first_name, school_liaison_last_name, school_liaison_phone, school_liaison_phone_extension, school_notes, serial_number, servicecontact_onbehalf, servicedeliverylog, servicelog, social_worker_at_termination, social_worker_at_termination_id, special_health_care_needs, state_case_number, teachers, termination_date, termination_destination, termination_reason, termination_reason_details, termination_reason_id, therapist, therapy_code, therapy_supervision_requirements, treatment_abilities, treatment_needs, treatment_preferences, treatment_strengths, treatmentneed, update_requested, update_requested_by, update_requested_by_id, update_requested_date, update_requested_note, updateable, use_number_required, uses_psychotropic_medication, visit_frequency_override, visit_frequency_override_id, visitation_restrictions, who_can_pickup_at_home, who_can_pickup_at_school, who_can_visit 

UPDATE - 추가 모델/잘못된 뷰 코드

models.py 
class ParentalGroup(models.Model): 
    many fields... 

class Placement(models.Model): 
    parental_group = models.ForeignKey(ParentalGroup, null=True, blank=True) 
    many more fields... 

class ServiceLog(models.Model): 
    parental_group = models.ForeignKey(ParentalGroup, null=True, blank=True) 
    placement = models.ManyToManyField(Placement, blank=True) 
    many more fields... 


views.py: 
data.service_log = ServiceLog.objects.filter(
    parental_group=data.pg, 
).prefetch_related(
    Prefetch(
     'placement', 
     queryset=Placement.objects.all(), 
     to_attr='placements' 
    ), 
) 

for service in data.service_log: 
    some code to generate data to pass to template... 

return render_to_response(...) 

Answer 1

나는 Gunicorn/장고의 runserver에 장고 1.8.6을 사용하여 비슷한 문제가 있었다. 필자는 쉘/노트북 환경에서도 오류를 재현하지 못했습니다.

ManyToManyField에 related_name을 추가하여 임의로 발생하는 FieldError를 해결했습니다. ManyToManyField에서 a through model을 사용했습니다. 귀하의 경우에는

:

class ServiceLog(models.Model): 
    parental_group = models.ForeignKey(ParentalGroup, null=True, blank=True) 
    placement = models.ManyToManyField(Placement, blank=True, related_name='servicelog') 

월