I have an invoicing rails app and I am trying to add a column that is called invoice_number and the table has a primary key of invoice_id I want invoice_number to be set on save and increment by 1
So every user should have invoices where the invoice_number starts from 1
The number I want to add is only for auditing purposes and should be private.
I wanted to know what the best way to do something like this would be
after_save :increment_invoice_number
private
def increment_invoice_number
self.invoice_number = current_user.invoice.count + 1
end
I know this block wont work but its kind of what im trying to do.
Does anyone know of a way I can achieve this?
The following should work... it assumes that you never destroy invoices (otherwise you may end up with duplicate invoice numbers)
before_save :increment_invoice_number
private
def increment_invoice_number
return if persisted?
self.invoice_number = user.invoices.count + 1
end
Note the return if persisted? which means you only set the invoice number for a new record, not for an existing one.
Related
I have made a previous post related to this problem here but because this is a related but new problem I thought it would be best to make another post for it.
I'm using Django 1.8
I have a User model and a UserAction model. A user has a type. UserAction has a time, which indicates how long the action took as well as a start_time which indicates when the action began. They look like this:
class User(models.Model):
user_type = models.IntegerField()
class UserAction:
user = models.ForeignKey(User)
time = models.IntegerField()
start_time = models.DateTimeField()
Now what I want to do is get all users of a given type and the sum of time of their actions, optionally filtered by the start_time.
What I am doing is something like this:
# stubbing in a start time to filter by
start_time = datetime.now() - datetime.timedelta(days=2)
# stubbing in a type
type = 2
# this gives me the users and the sum of the time of their actions, or 0 if no
# actions exist
q = User.objects.filter(user_type=type).values('id').annotate(total_time=Coalesce(Sum(useraction__time), 0)
# now I try to add the filter for start_time of the actions to be greater than or # equal to start_time
q = q.filter(useraction__start_time__gte=start_time)
Now what this does is of course is an INNER JOIN on UserAction, thus removing all the users without actions. What I really want to do is the equivalent of my LEFT JOIN with a WHERE clause, but for the life of me I can't find how to do that. I've looked at the docs, looked at the source but am not finding an answer. I'm (pretty) sure this is something that can be done, I'm just not seeing how. Could anyone point me in the right direction? Any help would be very much appreciated. Thanks much!
I'm having the same kind of problem as you. I haven't found any proper way of solving the problem yet, but I've found a few fixes.
One way would be looping through all the users:
q = User.objects.filter(user_type=type)
for (u in q):
u.time_sum = UserAction.filter(user=u, start_time__gte=start_time).aggregate(time_sum=Sum('time'))['time_sum']
This method does however a query at the database for each user. It might do the trick if you don't have many users, but might get very time-consuming if you have a large database.
Another way of solving the problem would be using the extra method of the QuerySet API. This is a method that is detailed in this blog post by Timmy O'Mahony.
valid_actions = UserAction.objects.filter(start_time__gte=start_time)
q = User.objects.filter(user_type=type).extra(select={
"time_sum": """
SELECT SUM(time)
FROM userAction
WHERE userAction.user_id = user.id
AND userAction.id IN %s
""" % (%s) % ",".join([str(uAction.id) for uAction in valid_actions.all()])
})
This method however relies on calling the database with the SQL table names, which is very un-Django - if you change the db_table of one of your databases or the db_column of one of their columns, this code will no longer work. It though only requires 2 queries, the first one to get the list of valid userAction and the other one to sum them to the matching user.
I have a database schema similar to this:
class User(models.Model):
… (Some fields irrelevant for this query)
class UserNotifiy(models.Model):
user = models.ForeignKey(User)
target = models.ForeignKey(<Some other Model>)
notification_level = models.SmallPositivIntegerField(choices=(1,2,3))
Now I want to query for all Users that have a UserNotify object for a specific target and at least a specific notification level (e.g. 2).
If I do something like this:
User.objects.filter(usernotify__target=desired_target,
usernotify__notification_level__gte=2)
I get all Users that have a UserNotify object for the specified target and at least one UserNotify object with a notification_level greater or equal to 2. These two UserNotify objects, however, do not have to be identical.
I am aware that I can do something like this:
user_ids = UserNotify.objects.filter(target=desired_target,
notification_level__gte=2).values_list('user_id', flat=True)
users = User.objects.filter(id__in=user_ids).distinct()
But this seems a step too much for me and I believe it executes two queries.
Is there a way to solve my problem with a single query?
Actually I don't see how you can run the first query, given that usernotify is not a valid field name for User.
You should start from UserNotify as you did in your second example:
UserNotify.objects.filter(
target=desired_target,
notification_level__gte=2
).select_related('user').values('user').distinct()
I've been looking for this behaviour but I've never found a better way than the one you describe (creating a query for user ids and inject it in a User query). Note this is not bad since if your database support subqueries, your code should fire only one request composed by a query and a subquery.
However, if you just need a particular field from the User objects (for example first_name), you may try
qs = (UserNotify.objects
.filter(target=desired_target, notification_level__gte=2)
.values_list('user_id', 'user__first_name')
.order_by('user_id')
.distinct('user_id')
)
I am not sure if I understood your question, but:
class User(models.Model):
… (Some fields irrelevant for this query)
class UserNotifiy(models.Model):
user = models.ForeignKey(User, related_name="notifications")
target = models.ForeignKey(<Some other Model>)
notification_level = models.SmallPositivIntegerField(choices=(1,2,3))
Then
users = User.objects.select_related('notifications').filter(notifications__target=desired_target,
notifications__notification_level__gte=2).distinct('id')
for user in users:
notifications = [x for x in user.notifications.all()]
I don't have my vagrant box handy now, but I believe this should work.
I have trouble to make these kind of queries with lots of joins. I didn't found examples, but I guess they are not so complicated to write. It's just there are several FKs.
Here is the models.py (not complicated)
class User(AbstractBaseUser, PermissionsMixin): # Django custom user model
# Some stuff
class CliProfile(models.Model):
user = models.OneToOneField(settings.AUTH_USER_MODEL)
class BizProfile(models.Model):
user = models.OneToOneField(settings.AUTH_USER_MODEL)
class Card(models.Model):
linked_client = models.ForeignKey(CliProfile, blank=True, null=True)
class Points(models.Model):
benef_card = models.ForeignKey(Card)
at_owner = models.ForeignKey(BizProfile)
creation_date = models.DateTimeField(auto_now_add=True)
Quick description of the model
a user can be a client (using CliProfile) or a business (using BizProfile)
each card is linked to a client
each card contains a [points - business] association
This way: a client has a card and can has 3 points at Pizza Hut, and 5 points at McDonalds with the same card)
The request I'm trying to write
Functionally speaking, the purpose is a owner (like PizzaHut) can see all his clients (client who have cards which has points at Pizza Hut)
Technically speaking, I'm trying to write a query to get all clients (ie. a CliProfile queryset) whose cards (at least 1 of all) whose points (at least 1 of all) whose owner (there is only 1) whose user (there is only 1) = request.user ?
Do you have any idea how to write such a query? Thanks a lot.
To match fields within models in filter() you need to use two underscores. The following worked for me
CliProfile.objects.filter(card__points__at_owner=request.user)
But #Alex's suggestion makes the most sense unless this was just an example of what you are trying to do.
If you wanted profiles that are associated with one of several cards you can use the __in field lookup:
CliProfile.objects.filter(card__in=IterableOfCards)
Also you don't use == in filter(). That would return True or False and then pass that value in the filter() call effectively making the call filter(True or False) which won't do anything useful. you have to use = because you are passing a named parameter into the filter function.
Why card instead of card_set()?
cart_set only exists within an instance of a CliProfile. You are not in an instance of a CliProfile, you are trying to get a list of them.
You can try it in the terminal and it will tell you the valid choices.
#Note that it doesn't matter what you put after=, since it fails before that is checked.
>>> CliProfile.objects.filter(card_set=True)
FieldError: Cannot resolve keyword 'card_set' into field. Choices are: card, id, user
a CliProfile can be referenced by multiple cards, which is why card_set exists in it but you are trying to match one card. The card whose points at_owner field is request.user.
You would use a_cliprofile_instance.card_set.filter() to get a subset of their cards or a_cliprofile_instance.card_set.all() to display all of their cards
I want to update budget of Category model in Django.
class Category(models.Model):
user = models.ForeignKey(User)
name = models.CharField(max_length=128)
budget = models.DecimalField(default=0.0, decimal_places=2, max_digits=12, help_text="Amount in dollars ($)")
I would have a list of new budget like this which is equal to number of data in Category:
>>> new_category_budget
[Decimal('2700.000'), Decimal('750.000'), Decimal('1500.000')]
I am updating like this:
>>> for budget in new_category_budget:
... Category.objects.filter(user=2).update(budget=budget)
...
3L
3L
3L
But all of these return the same data. What's wrong with my update statement?
What you're doing is iterating over your budget values, and updating all records with user=2 to each one, overriding the previous value.
The return value of QuerySet.update is the number of updated records. Each time you call update(), you get the result that 3 records were updated.
I don't quite understand what you are actually trying to do, but it might be something like this (untested!):
for (budget, category) in zip(new_category_budget, list(Category.objects.filter(user=2)):
category.budget=budget
category.save()
Of course, this assumes that the number of filtered categories will exactly match the number of budgets in new_category_budget, and also the order of iteration over categories is not obvious. All in all, this seems weird :)
When you call update on a QuerySet, it will set all items in the QuerySet to that value. See the example here.
So through your for loop, you are updating all the Category objects with user=2 to each budget. At the end of the for loop, all the Category objects should be have budget == new_category_budget[-1] or the last budget item.
If you want different values for each Category object, you'll need to call save on them individually.
I need to group all entries by user and get the count doing something like this:
class Promotion(models.Model):
pass
class Entry(models.Model):
user = models.ForeignKey('User');
promotion = models.ForeignKey('Promotion')
def get_uniques(promotion_id):
promotion = Promotion.objects.get(promotion_id)
entries = promotion.entry_set.annotate(Count('user'))
return entries
However it's returning the same user multiple times. I've also tried the following after looking around StackOverflow, and it seem to be doing something other than what I want:
promotion.entry_set.annotate(Count('user')).order_by('user')[:10]
promotion.entry_set.all().values('user').annotate(entry_count=Count('user')).order_by()
Entry.objects.filter(promotion=promotion).annotate(Count('user')).order_by('user')
Basically I'm trying to do this, giving me an Entry object for each user:
Entry.objects.raw("""
SELECT *
FROM promotion_entry
WHERE promotion_id = %s
GROUP BY user_id""", (promotion_id,))
Then I'll perform a second query to get the entry count, still not ideal. Can I do a GROUP BY without raw?
There seem to be a ticket that would let me do what I want in the future over on the bugtracker by enabling DISTINCT ON: https://code.djangoproject.com/ticket/6422
If you want to count entries for each user use:
promotion.entry_set.all().values('user').annotate(entry_count=Count('id')).order_by()
If you want some entry for each user use:
promotion.entry_set.all().values('user').annotate(entry_id=Max('id')).order_by()
This will give you id's of entries, use __in to get objects themselves.