Уважаемое сообщество StackOverflow. Мой вопрос связан со вставкой новой записи в таблицу, содержащую поле many2many fields.
Целый день я пытался решить эту проблему самостоятельно, читал документацию по django и рылся в stackoverflow.
Мои модели.py:
from django.db import models
from django_extensions.db.models import TimeStampedModel
class clans(TimeStampedModel):
rfam_acc = models.CharField(max_length=7)
rfam_id = models.CharField(max_length=40)
description = models.CharField(max_length=100)
author = models.CharField(max_length=100)
comment = models.CharField(max_length=2000, null=True)
class Meta:
ordering = ('rfam_id',)
def __str__(self):
return self.rfam_id
class families(TimeStampedModel):
rfam_acc = models.CharField(max_length=7)
rfam_id = models.CharField(max_length=40)
description = models.CharField(max_length=75)
author = models.CharField(max_length=100)
clan = models.ManyToManyField(clans, null=True, blank=True)
comment = models.CharField(max_length=2000, null=True)
мой скрипт для сбора данных (из другой базы данных) и вставки в мою БД: (это запускается из manage.py shell_plus).
import mysql.connector
from browse.models import clans, families
def run():
#... Query from another DB
# Query for clans using cursor. assign results to list of lists row_clans
query_clans = ("SELECT c.clan_acc, c.id, c.description, c.author, c.comment FROM clan c")
cursor_clans.execute(query_clans)
row_clans = cursor_clans.fetchall()
# Creation of entry clans in the database.
for clan in row_clans:
clap = clans.objects.create(
rfam_acc=clan[0],
rfam_id=clan[1],
description=clan[2],
author=clan[3],
comment=clan[4],
)
# Query for families, that have clan = just created clan. Result in a list of lists row_family.
query_families = ("SELECT f.rfam_acc, f.rfam_id, f.description, f.author, f.comment, c.id FROM clan_membership cm, family f, clan c WHERE f.rfam_acc = cm.rfam_acc AND cm.clan_acc = c.clan_acc AND c.id =")
cursor_families.execute(query_families + "\"" + clan[1] + "\"")
row_family = cursor_families.fetchall()
# Creation of entryes families in the database.
for family in row_family:
families.objects.create(
rfam_acc=family[0],
rfam_id=family[1],
description=family[2],
author=family[3],
comment=family[4],
clan=clan[1]
)
print ("insert family ", family[1], " in ", clan[1])
# close the cursors and close the connection to the server
cursor_clans.close()
cursor_families.close()
cnx.close()
И, наконец, ошибка в оболочке:
Traceback (most recent call last):
File "<console>", line 1, in <module>
File "/Users/work/Desktop/StructuRNA/website/scripts/SQLfromRfamIntoClansFamily.py", line 42, in run
clan=clan[1]
File "/Users/work/Desktop/StructuRNA/.VirEnvStructuRna/lib/python3.6/site-packages/django/db/models/manager.py", line 85, in manager_method
return getattr(self.get_queryset(), name)(*args, **kwargs)
File "/Users/work/Desktop/StructuRNA/.VirEnvStructuRna/lib/python3.6/site-packages/django/db/models/query.py", line 397, in create
obj = self.model(**kwargs)
File "/Users/work/Desktop/StructuRNA/.VirEnvStructuRna/lib/python3.6/site-packages/django/db/models/base.py", line 550, in __init__
setattr(self, prop, kwargs[prop])
File "/Users/work/Desktop/StructuRNA/.VirEnvStructuRna/lib/python3.6/site-packages/django/db/models/fields/related_descriptors.py", line 499, in __set__
manager = self.__get__(instance)
File "/Users/work/Desktop/StructuRNA/.VirEnvStructuRna/lib/python3.6/site-packages/django/db/models/fields/related_descriptors.py", line 476, in __get__
return self.related_manager_cls(instance)
File "/Users/work/Desktop/StructuRNA/.VirEnvStructuRna/lib/python3.6/site-packages/django/db/models/fields/related_descriptors.py", line 783, in __init__
(instance, self.source_field_name))
ValueError: "<families: families object>" needs to have a value for field "families" before this many-to-many relationship can be used.
Любая помощь? Я не могу понять, что не работает.
Еще забавно, что в своей базе данных я нашел вставку первого элемента (повторяющуюся столько раз, сколько я пытался запустить скрипт). Этот элемент также имеет правильное значение для полей m2m.
