Here is my problem. I have a model Project, that has a quote field in it. When a new instance of project is created I need to append the last 2 digits of the year plus a hyphen onto the start of the "quote" field. Ex. 2010 = "10-". Im just not quite sure how to start it?
As of right now I have hard coded in "10-" in as a pre-quote field, but I do not want to have to do that.
models.py
class Project(models.Model):
client = models.ForeignKey(Clients, related_name='projects')
created_by = models.ForeignKey(User, related_name='created_by')
#general information
proj_name = models.CharField(max_length=255, verbose_name='Project Name')
pre_quote = models.CharField(max_length=3,default='10-')
quote = models.IntegerField(max_length=10, verbose_name='Quote #', unique=True)
desc = models.TextField(verbose_name='Description')
starts_on = models.DateField(verbose_name='Start Date')
completed_on = models.DateField(verbose_name='Finished On')
Anyone have to do this before? Or have any suggestions?
Try this:
def save(self):
today = datetime.date.today()
self.quote = "%s-%s" % (str(today.year)[2:4], self.quote)
Assuming you imported datetime.
Your existing quote field is set as an integer. You will need to set this as a text field. Once you do that, you can override the save() function to prepend "10-" to the field.
class Project(models.Model):
client = models.ForeignKey(Clients, related_name='projects')
created_by = models.ForeignKey(User, related_name='created_by')
proj_name = models.CharField(max_length=255, verbose_name='Project Name')
quote = models.TextField(max_length=10, verbose_name='Quote #', unique=True)
desc = models.TextField(verbose_name='Description')
starts_on = models.DateField(verbose_name='Start Date')
completed_on = models.DateField(verbose_name='Finished On')
def save(self):
self.quote = "10-" + self.quote
Related
I have 2 models Transaction and FamilyGroup and im making some validations like below
class Transaction(models.Model):
chp_reference = models.CharField(max_length=50, unique=True)
rent_effective_date = models.DateField(null=True, blank=True)
income_period = models.CharField(max_length=11)
property_market_rent = models.DecimalField(max_digits=7)
number_of_familygroup = models.DecilmalField(max_digits=10)
def clean(self):
count_fg = self.family_groups.count()
if self.number_of_family_group != count_fg:
raise ValidationError(
' Number of family group doesnt match with FG_NO.')
class FamilyGroup(models.Model):
name = models.CharField(max_length=10)
transaction = models.ForeignKey(Transaction,
on_delete=models.CASCADE,related_name='family_groups')
last_rent = models.DecimalField(max_digits=7)
the probelm is when i change number_of_familygroup to eg. 3 and i make 3 FamilyGroup objects, it still give me an error Number of family group doesnt match with FG_NO , it doesnt let me save the new values. What is the best approach to make it work properly? Thanks in advance!
I'm trying to save Authors model, but it keeps saving twice into the database.
views.py
........................
for book_data in data['items']:
volume_info = book_data['volumeInfo']
title = volume_info['title']
genres = volume_info.get('categories')
authors = volume_info.get('authors')
description = volume_info.get('description')
if not Books.objects.filter(title=title).exists():
book = Books.objects.create(title=title, description=description)
# Does authors exists in database?
existing_authors = Authors.objects.filter(author_name__in=authors)
existing_authors_names = {authors.author_name for authors in existing_authors}
# Create a list of missing authors
missing_authors = [
Authors(author_name=author_name)
for author_name in authors
if author_name not in existing_authors_names
]
# Creating author before adding it to relation
if missing_authors:
missing_authors = Authors.objects.bulk_create(missing_authors)
print(missing_authors)
for m in missing_authors:
m.save()
# Adding to relation
book.authors.add(*existing_authors, *missing_authors)
..........................
I think the problem is in for m in missing_authors right?
models.py
class Authors(models.Model):
author_name = models.CharField(max_length=200)
def __str__(self):
return self.author_name
class Books(models.Model):
title = models.CharField(max_length=300)
description = models.TextField(blank=True, null=True)
authors = models.ManyToManyField(Authors, blank=True)
genres = models.ManyToManyField(Genres, blank=True)
def __str__(self):
return self.title
database is sqllite3
Django version is 2.2.1
The bulk_create method automatically saves the results after the query is executed.
Change your code to this:
if missing_authors:
Authors.objects.bulk_create(missing_authors)
''' remove these lines
for m in missing_authors:
m.save()
#not sure what this line is doing exactly, but it might be causing your problem
book.authors.add(*existing_authors, *missing_authors)
'''
Update
If you can set unique=True for your author_name column, then try the following:
class Authors(models.Model):
author_name = models.CharField(max_length=200, unique=True)
Authors.objects.bulk_create(missing_authors, ignore_conflicts=True)
for m in missing_authors:
m.save()
book.authors.add(*existing_authors, *missing_authors)
I'm working on this big project with Django and I have to update the database. I have to add another table which will replace another later.
So I want to add in a model the possibility to have a field where I can have either the old model OR the new one.
Here is the code of the old model:
class Harvests(models.Model):
ident_culture = models.IntegerField(primary_key=True)
intitule_culture = models.CharField(max_length=50, blank=True)
nom_fertiweb = models.CharField(max_length=50, blank=True, null = True)
affichage_quintaux_tonne = models.CharField(max_length=1,
choices=RENDEMENT_CHOICES, default = 'T')
type_culture = models.ForeignKey("TypeCulture", null=True)
slug = models.SlugField(null=True, blank=True)
image = models.ImageField(upload_to = 'images_doc_culture/',
null=True, blank = True)
affichage = models.BooleanField(default = True)
class Meta:
verbose_name = "Liste - Culture"
verbose_name_plural = "Liste - Cultures"
ordering = ['intitule_culture']
def __str__(self):
return self.intitule_culture
def label(self):
return self.intitule_culture or ''
#classmethod
def get_choices(cls):
choices = [('', corp.EMPTY_CHOICE_LBL)]
c_category_lbl, c_category = '', []
for item in cls.objects.all():
choices.append((item.pk, item.intitule_culture))
return choices
And there is the code od the new one I created:
class Crops(models.Model):
intitule_culture = models.CharField(max_length=75, blank=True)
affichage_quintaux_tonne = models.CharField(max_length=2,
choices=RENDEMENT_CHOICES, default = 'T')
type_culture = models.ForeignKey("TypeCulture", null=True)
ident_culture = models.IntegerField(primary_key=True)
affichage = models.BooleanField(default = True)
id_marle = models.IntegerField(null=True)
class Meta:
verbose_name = "Liste - Culture 2019"
verbose_name_plural = "Liste - Cultures 2019"
ordering = ['intitule_culture']
def __str__(self):
return self.intitule_culture
def label(self):
return self.intitule_culture or ''
#classmethod
def get_choices(cls):
choices = [('', corp.EMPTY_CHOICE_LBL)]
c_category_lbl, c_category = '', []
for item in cls.objects.all():
choices.append((item.pk, item.intitule_culture))
return choices
I want to accept both models in the field culture in this model:
class CompanyHarvest(models.Model):
company = models.ForeignKey('corp.Company', verbose_name='Exploitation',
related_name ='cultures')
culture = models.ForeignKey(Harvests, verbose_name ='Culture')
precision = models.CharField(max_length=255, blank=True)
saison_culture = models.CharField(max_length=1, choices=SAISON_CHOICES,
default = 'P')
class Meta:
verbose_name = "Expl. - Culture"
verbose_name_plural = "Expl. - Cultures"
unique_together = ('company', 'culture', 'precision', 'saison_culture')
def __str__(self):
return str(self.culture) + ' ' + self.precision + \
' ' + str(self.get_saison_culture_display() )
#property
def slug(self):
return "_".join([slugify(str(self.culture or '')),
slugify(str(self.precision or ''))]
)
I'm new to Django, can anyone help me with this please ? (^-^)
This is not possible - at least not this way. And this is not a Django limitation but a SQL one, a foreign key cannot reference either one table or another.
A possible and simple obvious solution here would be to have two foreign keys in CompanyHarvest - one for each of the old and new model -, each with blank=True et default=None, but it can quickly make a mess of all the client code (all code using CompanyHarvest).
Much better solutions would be to either only keep the existing model (adding any new field/feature to it and eventually hiding obsolete ones) or migrate all old model records to the new model (this can be combined with the naive "two foreign keys" solution so you can keep the old table and records as archives if necessary).
Also - totally unrelated but -, this:
#classmethod
def get_choices(cls):
choices = [('', corp.EMPTY_CHOICE_LBL)]
c_category_lbl, c_category = '', []
for item in cls.objects.all():
choices.append((item.pk, item.intitule_culture))
return choices
1/ should be defined on the manager (cf https://docs.djangoproject.com/en/2.1/topics/db/managers/#adding-extra-manager-methods)
2/ should be written using .values() queryset (which will save on both the db query and building full-blown instances for no good reason):
for item in cls.objects.values("pk", "intitule_culture"):
choices.append(item)
3/ and could very possibly (i'd have to see how it's used) replaced by a ModelChoiceField in the calling code.
Oh and yes: if you allow blanks for text fields, you very probably want to force the empty string as default so you don't two possible (and incompatible) cases (sql NULL and the empty string) when no value is given.
I'm making a program that helps log missions in a game. In each of these missions I would like to be able to select a number of astronauts that will go along with it out of the astronauts table. This is fine when I only need one, but how could I approach multiple foreign keys in a field?
I currently use a 'binary' string that specifies which astronauts are to be associated with the mission (1 refers to Jeb, but not Bill, Bob, or Val and 0001 means only Val), with the first digit specifying the astronaut with id 1 and so forth. This works, but it feels quite clunky.
Here's the model.py for the two tables in question.
class astronauts(models.Model):
name = models.CharField(max_length=200)
adddate = models.IntegerField(default=0)
experience = models.IntegerField(default=0)
career = models.CharField(max_length=9, blank=True, null=True)
alive = models.BooleanField(default=True)
def __str__(self):
return self.name
class Meta:
verbose_name_plural = "Kerbals"
class missions(models.Model):
# mission details
programid = models.ForeignKey(programs, on_delete=models.SET("Unknown"))
missionid = models.IntegerField(default=0)
status = models.ForeignKey(
missionstatuses, on_delete=models.SET("Unknown"))
plan = models.CharField(max_length=1000)
# launch
launchdate = models.IntegerField(default=0)
crewmembers = models.IntegerField(default=0)
# recovery
summary = models.CharField(max_length=1000, blank=True)
recdate = models.IntegerField(default=0)
def __str__(self):
return str(self.programid) + '-' + str(self.missionid)
class Meta:
verbose_name_plural = "Missions"
I saw a post about an 'intermediate linking table' to store the crew list but that also isn't ideal.
Thanks!
This is the use case for Django's ManyToManyField. Change the appropriate field on the missions:
class missions(models.Model):
crewmembers = models.ManyToManyField('astronauts')
You can access this from the Astronaut model side like so:
jeb = astronaut.objects.get(name='Jebediah Kerman')
crewed_missions = jeb.missions_set.all()
Or from the mission side like so:
mission = missions.objects.order_by('?')[0]
crew = mission.crewmembers.all()
This creates another table in the database, in case that is somehow a problem for you.
I'm asking if I set up the create method up correctly. Or does it need to be added for the other two models as well? How would this be changed?
class PointModel(models.Model):
x = models.IntegerField()
y = models.IntegerField()
index = models.IntegerField()
class DatetimeRangeModel(models.Model):
start_datetime = models.CharField(max_length=14)
end_datetime = models.CharField(max_length=14)
class PlanModel(models.Model):
data_number = models.IntegerField()
data_datetime_range = models.ForeignKey(DatetimeRangeModel, blank=True, null=True, on_delete=models.SET_NULL)
data_polygon = models.ForeignKey(PointModel, blank=True, null=True, on_delete=models.SET_NULL)
#classmethod
def create(cls, data_number, data_datetime_range, data_polygon):
plan = cls(data_number=data_number, data_datetime_range = data_datetime_range,
data_polygon=data_polygon)
return plan
EDIT: I change the structure which fixed the undefined and added some logic that prevents the PlanModel from being deleted with the "blank=True, null=True, on_delete=models.SET_NULL"
Does this look right?
see the docs for creating objects
#classmethod
def create(cls, title):
book = cls(title=title)
# do something with the book
return book
there's no much reason to add those unless you have something to add there on the # do something with the book line
EDIT: instead of calling create you're usually do:
plan = PlanModel(data_number=1, ....)
plan.save()
or sometimes:
plan = PlanModel()
plan.data_number=1
...
plan.save()