I'd like to Sum the post_value of all of the Posts for each post_user to eventually use in a chart. I'm struggling with how to formulate the query?
So far, I've got to:
user_totals = User.objects.annotate(post_value_total=Sum('post'))
models.py
class User(AbstractUser):
pass
class Post(models.Model):
post_user = models.ForeignKey(User, on_delete=models.CASCADE)
post_cat = models.ForeignKey(Category, on_delete=models.CASCADE)
post_action = models.ForeignKey(Action, on_delete=models.CASCADE)
post_quantity = models.PositiveIntegerField(blank=True, null=True)
post_value = models.PositiveIntegerField(default='0')
post_timestamp = models.DateTimeField(auto_now_add=True)
def __str__(self):
return f"{self.post_user}'s post at {self.post_timestamp}"
Thanks.
I'd like to Sum the post_value of all of the Posts for each post_user to eventually use in a chart.
Since each Post has a non-nullable post_user ForeignKey, it means that each Post belongs to exactly one user.
We thus can sum up the number of post_values of all Users with:
Post.objects.all().count()
If you only want to sum these up for a subset of the users, you can work with:
Post.objects.filter(
post_user__in=[user1, user2, user3]
).count()
or if you have ids:
Post.objects.filter(
post_user_id__in=[user_id1, user_id2, user_id3]
).count()
Or if you want to sum up the post_values, you can work with:
from django.db.models import Sum
total_post_value = Post.objects.aggregate(
total=Sum('post_value')
) or 0
The or 0 is necessary if the collection can be empty, since the sum of no records is NULL/None, not 0.
Or if you want to do this per User, we can work with:
user_totals = User.objects.annotate(
post_value_total=Sum('post__post_value')
)
The User objects that arise from this will have an extra attribute post_value_total that sums up the values of the related Posts. These can be None if a user has no related Posts. In that case we can work Coalesce [Django-doc]:
from django.db.models import Sum, Value
from django.db.models.functions import Coalesce
user_totals = User.objects.annotate(
post_value_total=Coalesce(Sum('post__post_value'), Value(0))
)
Maybe i have an understanding problem. I try to make 2 tabeles in one database. But additionaly i need to have some temporary values in one class that i doen´t want to write to the database.
I try to switch to peewee and read the dokumentation but i find no solution at my own.
without peewee i would make an init method where i write my attributes. But where did i have to write them now?
from peewee import *
import datetime
db = SqliteDatabase('test.db', pragmas={'foreign_keys': 1})
class BaseModel(Model):
class Meta:
database = db
class Sensor(BaseModel):
id = IntegerField(primary_key=True)
sort = IntegerField()
name = TextField()
#def __init__(self):
#self.sometemporaryvariable = "blabla"
def meineparameter(self, hui):
self.hui = hui
print(self.hui)
class Sensor_measure(BaseModel):
id = ForeignKeyField(Sensor, backref="sensorvalues")
timestamp = DateTimeField(default=datetime.datetime.now)
value = FloatField()
class Meta:
primary_key = CompositeKey("id", "timestamp")
db.connect()
db.create_tables([Sensor_measure, Sensor])
sensor1 = Sensor.create(id=2, sort=20, name="Sensor2")
#sensor1.sometemporaryvariable = "not so important to write to the database"
sensor1.save()
Remember to call super() whenever overriding a method in a subclass:
class Sensor(BaseModel):
id = IntegerField(primary_key=True)
sort = IntegerField()
name = TextField()
def __init__(self, **kwargs):
self.sometemporaryvariable = "blabla"
super().__init__(**kwargs)
I am trying to create a simple npyscreen curses application in python that requests user input on one screen, and then verifies it for the user on another screen.
Mostly, this is an effort to understand how values are stored and retrieved from within npyscreen. I am sure I am missing something simple, but I have been unable to find (or understand?) the answer within the documentation.
Sample code below which will not pass the value properly:
#!/usr/bin/env python3.5
import npyscreen as np
class EmployeeForm(np.Form):
def afterEditing(self):
self.parentApp.switchForm('CONFIRMFM')
def create(self):
self.myName = self.add(np.TitleText, name='Name')
self.myDepartment = self.add(np.TitleSelectOne, scroll_exit=True, max_height=3, name='Department', values = ['Department 1', 'Department 2', 'Department 3'])
self.myDate = self.add(np.TitleDateCombo, name='Date Employed')
class EmployeeConfirmForm(np.Form):
def afterEditing(self):
self.parentApp.setNextForm(None)
def create(self):
self.value = None
self.wgName = self.add(np.TitleText, name = "Name:",)
self.wgDept = self.add(np.TitleText, name = "Dept:")
self.wgEmp = self.add(np.TitleText, name = "Employed:")
def beforeEditing(self):
if self.value:
self.name = "Is this correct?"
self.wgName.value = self.myName.value
self.wgDept.value = self.myDepartment.value
self.wgEmp.value = self.myDate.value
def on_cancel(self):
self.parentApp.switchFormPrevious()
class myApp(np.NPSAppManaged):
def onStart(self):
self.addForm('MAIN', EmployeeForm, name='Employee Entry')
self.addForm('CONFIRMFM', EmployeeConfirmForm, name='Employee Confirmation')
if __name__ == '__main__':
TestApp = myApp().run()
I haven't found a straightforward way to directly pass variables between forms. However, you can work around this by using variables that have a global scope among forms.
The NPSAppManaged app class runs completely encapsulated, so if you try to declare global variables at the top of the Python file, the forms within will not have access to them. Instead, declare the variables inside the NPSAppManaged app class before the onStart method as shown below.
class myApp(np.NPSAppManaged):
# declare variables here that have global scope to all your forms
myName, myDepartment, myDate = None, None, None
def onStart(self):
self.addForm('MAIN', EmployeeForm, name='Employee Entry')
self.addForm('CONFIRMFM', EmployeeConfirmForm, name='Employee Confirmation')
if __name__ == '__main__':
TestApp = myApp().run()
You can then access these variables using self.parentApp.[variable name] as follows:
class EmployeeConfirmForm(np.Form):
def afterEditing(self):
self.parentApp.setNextForm(None)
def create(self):
self.add(np.FixedText, value = "Is this correct?")
self.wgName = self.add(np.TitleText, name = "Name:", value = self.parentApp.myName)
self.wgDept = self.add(np.TitleText, name = "Dept:", value = self.parentApp.myDepartment)
self.wgEmp = self.add(np.TitleText, name = "Employed:", value = self.parentApp.myDate)
def on_cancel(self):
self.parentApp.switchFormPrevious()
Note: you don't need to have a separate beforeEditing method since the values will be loaded directly into EmployeeConfirmForm during the create method from the app class global variables.
One way to do this is to use getForm before switchForm to pass the values. The following works for me using python2 to pass the name. Passing other values should be similar. I'm very much learning this myself but please comment if you have further questions.
import npyscreen as np
class EmployeeForm(np.ActionForm):
def create(self):
self.myName = self.add(np.TitleText, name='Name')
self.myDepartment = self.add(np.TitleSelectOne, scroll_exit=True, max_height=3, name='Department', values = ['Department 1', 'Department 2', 'Department 3'])
self.myDate = self.add(np.TitleDateCombo, name='Date Employed')
def afterEditing(self):
self.parentApp.getForm('CONFIRMFM').wgName.value = self.myName.value
self.parentApp.switchForm('CONFIRMFM')
class EmployeeConfirmForm(np.Form):
def afterEditing(self):
self.parentApp.setNextForm(None)
def create(self):
self.value = None
self.wgName = self.add(np.TitleFixedText, name = "Name:",)
self.wgDept = self.add(np.TitleText, name = "Dept:")
self.wgEmp = self.add(np.TitleText, name = "Employed:")
def on_cancel(self):
self.parentApp.switchFormPrevious()
class myApp(np.NPSAppManaged):
def onStart(self):
self.addForm('MAIN', EmployeeForm, name='Employee Entry')
self.addForm('CONFIRMFM', EmployeeConfirmForm, name='Employee Confirmation')
if __name__ == '__main__':
TestApp = myApp().run()
Assign values (including the value returned by addForm) to self.whatever.
So if you do
self.myAppValue = 2
self.mainForm = self.addForm('MAIN', MainForm, ...)
self.form2 = self.addForm('FORM2', Form2, ...)
you can use these in any form
self.parentApp.myAppValue
self.parentApp.mainForm.main_form_widget.main_form_value
And in myApp() you can do
self.mainForm.main_form_widget.main_form_value
I had the same problems during development as the documentation is not very detailed about passing values between forms.
I have added a few modification, the first one was changing Form to ActionForm in the confirmation form to have access to ok and cancel buttons. Secondly, the values on the confirmation form should not be editable as this is a confirmation. You can press cancel to edit on the previous form. The last one was passing the first element of the department list rather than the value - it would be just a list index. I hope it helps a little.
#!/usr/bin/env python3.5
import npyscreen as np
class EmployeeForm(np.Form):
def create(self):
self.myName = self.add(np.TitleText, name='Name')
self.myDepartment = self.add(np.TitleSelectOne, scroll_exit=True, max_height=3, name='Department', values = ['Department 1', 'Department 2', 'Department 3'])
self.myDate = self.add(np.TitleDateCombo, name='Date Employed')
def afterEditing(self):
self.parentApp.switchForm('CONFIRMFM')
self.parentApp.getForm('CONFIRMFM').wgName.value = self.myName.value
self.parentApp.getForm('CONFIRMFM').wgDept.value = self.myDepartment.values[0]
self.parentApp.getForm('CONFIRMFM').wgEmp.value = self.myDate.value
class EmployeeConfirmForm(np.ActionForm):
def create(self):
self.add(np.FixedText, value="Is this correct?", editable=False)
self.wgName = self.add(np.TitleText, name = "Name:", editable=False)
self.wgDept = self.add(np.TitleText, name = "Dept:", editable=False)
self.wgEmp = self.add(np.TitleText, name = "Employed:", editable=False)
def on_ok(self):
self.parentApp.setNextForm(None)
def on_cancel(self):
self.parentApp.switchFormPrevious()
class myApp(np.NPSAppManaged):
def onStart(self):
self.addForm('MAIN', EmployeeForm, name='Employee Entry')
self.addForm('CONFIRMFM', EmployeeConfirmForm, name='Employee Confirmation')
if __name__ == '__main__':
TestApp = myApp().run()
I am working on this problem a couple of days, my idea is from this model:
class oceni(db.Model):
user = db.UserProperty()
weight = db.FloatProperty()
item = db.StringProperty()
..to create a dictionary in this format:
collection = dict()
collection = {
'user1':{'item1':weight1,'item2':weight2..},
'user2':{'item3':weight3,'item4':weight4..},
..}
..and as far as I reached is this:
kontenier = db.GqlQuery('SELECT * FROM oceni')
kolekcija = dict()
tmp = dict()
lista = []
for it in kontenier:
lista.append(it.user)
set = []
for e in lista:
if e not in set:
set.append(e)
for i in set:
kontenier = db.GqlQuery('SELECT * FROM oceni WHERE user=:1',i)
for it in kontenier:
tmp[it.item]=it.weight
kolekcija[i]=tmp
..but this creates a dictionary where all the users have the same dictionary with items and their weight. I know this isn't the most pythonic way, but I'm new to this so I will be eager to learn something more about this problem.
I've used your variable names your notation in this snippet.
kontenier = db.GqlQuery('SELECT * FROM oceni')
kolekcija = {}
for it in kontenier:
if it.user not in kolekcija:
kolekcija[it.user] = {}
kolekcija[it.user][it.item] = it.weight
I have a datastore model representing items in an ecommerce site:
class Item(db.Model):
CSIN = db.IntegerProperty()
name = db.StringProperty()
price = db.IntegerProperty()
quantity = db.IntegerProperty()
Is there some way to enforce integrity constraints? For instance, I would like to make sure that quantity is never set to be less than 0.
The Property constructor lets you specify a function with the 'validator' named argument. This function should take one argument, the value, and raise an exception if the valid is invalid. For example:
def range_validator(minval, maxval):
def validator(v):
if (minval is not None and v < minval) or (maxval is not None and v > maxval):
raise ValueError("Value %s outside range (%s, %s)" % (v, minval, maxval))
return validator
class Item(db.Model):
CSIN = db.IntegerProperty()
name = db.StringProperty()
price = db.IntegerProperty()
quantity = db.IntegerProperty(validator=range_validator(0, None))
Note that the example uses a nested function to define general-purpose validators - you can, of course, use simple functions if you want to write a more special purpose validator.