Create model method using fields from two different models?
I am trying to create a model method that takes data from a field in one model and performs simple arithmetic using data from a field in another model. I am not trying to create a QuerySet in views.py, rather I am trying to create a model method in models.py that I can easily access via a context variable in my html (e.g. obj.model.modelmethod).
Below is a very simplified version of my models (before adding the desired model method):
class Person(models.Model):
'''
This table serves as the ultimate parent.
'''
id = models.IntegerField(auto_created=False, primary_key=True)
name = models.CharField(max_length=128, null=True, blank=True)
def __str__(self):
return self.name
class SalaryYearOne(models.Model):
id = models.OneToOneField(
Person,
on_delete=models.DO_NOTHING,
db_constraint=False,
primary_key=True
)
salary1 = models.IntegerField(null=True, blank=True)
class SalaryYearTwo(models.Model):
id = models.OneToOneField(
Person,
on_delete=models.DO_NOTHING,
db_constraint=False,
primary_key=True
)
salary2 = models.IntegerField(null=True, blank=True)
The model method I want to create will be under the SalaryYearOne class. The goal is calculate the salary percent change year-over-year (rounded to two decimal places). For example:
class SalaryYearOne(models.Model):
...
def salary_percent_change(self):
return round((self.salary1 - self.salary2) / self.salary2, 2)
The aforementioned is more for illustrative purposes. I understand that there are several issues with it as written. For example, I understand that the SalaryYearOne table does not have a field named salary2 etc. However, I hope this clearly shows my intent. Lastly, for further background the instance of Person will be selected from a ListView and I want to be able to display salary_percent_change as a context variable in my html through my DetailView.
How would you recommend I go about this?
django python-3.x django-models django-templates django-views
asked Nov 26 '18 at 0:08
jc4mjc4m
62
add a comment |
I am trying to create a model method that takes data from a field in one model and performs simple arithmetic using data from a field in another model. I am not trying to create a QuerySet in views.py, rather I am trying to create a model method in models.py that I can easily access via a context variable in my html (e.g. obj.model.modelmethod).
Below is a very simplified version of my models (before adding the desired model method):
class Person(models.Model):
'''
This table serves as the ultimate parent.
'''
id = models.IntegerField(auto_created=False, primary_key=True)
name = models.CharField(max_length=128, null=True, blank=True)
def __str__(self):
return self.name
class SalaryYearOne(models.Model):
id = models.OneToOneField(
Person,
on_delete=models.DO_NOTHING,
db_constraint=False,
primary_key=True
)
salary1 = models.IntegerField(null=True, blank=True)
class SalaryYearTwo(models.Model):
id = models.OneToOneField(
Person,
on_delete=models.DO_NOTHING,
db_constraint=False,
primary_key=True
)
salary2 = models.IntegerField(null=True, blank=True)
The model method I want to create will be under the SalaryYearOne class. The goal is calculate the salary percent change year-over-year (rounded to two decimal places). For example:
class SalaryYearOne(models.Model):
...
def salary_percent_change(self):
return round((self.salary1 - self.salary2) / self.salary2, 2)
The aforementioned is more for illustrative purposes. I understand that there are several issues with it as written. For example, I understand that the SalaryYearOne table does not have a field named salary2 etc. However, I hope this clearly shows my intent. Lastly, for further background the instance of Person will be selected from a ListView and I want to be able to display salary_percent_change as a context variable in my html through my DetailView.
How would you recommend I go about this?
django python-3.x django-models django-templates django-views
asked Nov 26 '18 at 0:08
jc4mjc4m
62
add a comment |
I am trying to create a model method that takes data from a field in one model and performs simple arithmetic using data from a field in another model. I am not trying to create a QuerySet in views.py, rather I am trying to create a model method in models.py that I can easily access via a context variable in my html (e.g. obj.model.modelmethod).
Below is a very simplified version of my models (before adding the desired model method):
class Person(models.Model):
'''
This table serves as the ultimate parent.
'''
id = models.IntegerField(auto_created=False, primary_key=True)
name = models.CharField(max_length=128, null=True, blank=True)
def __str__(self):
return self.name
class SalaryYearOne(models.Model):
id = models.OneToOneField(
Person,
on_delete=models.DO_NOTHING,
db_constraint=False,
primary_key=True
)
salary1 = models.IntegerField(null=True, blank=True)
class SalaryYearTwo(models.Model):
id = models.OneToOneField(
Person,
on_delete=models.DO_NOTHING,
db_constraint=False,
primary_key=True
)
salary2 = models.IntegerField(null=True, blank=True)
The model method I want to create will be under the SalaryYearOne class. The goal is calculate the salary percent change year-over-year (rounded to two decimal places). For example:
class SalaryYearOne(models.Model):
...
def salary_percent_change(self):
return round((self.salary1 - self.salary2) / self.salary2, 2)
The aforementioned is more for illustrative purposes. I understand that there are several issues with it as written. For example, I understand that the SalaryYearOne table does not have a field named salary2 etc. However, I hope this clearly shows my intent. Lastly, for further background the instance of Person will be selected from a ListView and I want to be able to display salary_percent_change as a context variable in my html through my DetailView.
How would you recommend I go about this?
django python-3.x django-models django-templates django-views
asked Nov 26 '18 at 0:08
jc4mjc4m
62
I am trying to create a model method that takes data from a field in one model and performs simple arithmetic using data from a field in another model. I am not trying to create a QuerySet in views.py, rather I am trying to create a model method in models.py that I can easily access via a context variable in my html (e.g. obj.model.modelmethod).
Below is a very simplified version of my models (before adding the desired model method):
class Person(models.Model):
'''
This table serves as the ultimate parent.
'''
id = models.IntegerField(auto_created=False, primary_key=True)
name = models.CharField(max_length=128, null=True, blank=True)
def __str__(self):
return self.name
class SalaryYearOne(models.Model):
id = models.OneToOneField(
Person,
on_delete=models.DO_NOTHING,
db_constraint=False,
primary_key=True
)
salary1 = models.IntegerField(null=True, blank=True)
class SalaryYearTwo(models.Model):
id = models.OneToOneField(
Person,
on_delete=models.DO_NOTHING,
db_constraint=False,
primary_key=True
)
salary2 = models.IntegerField(null=True, blank=True)
The model method I want to create will be under the SalaryYearOne class. The goal is calculate the salary percent change year-over-year (rounded to two decimal places). For example:
class SalaryYearOne(models.Model):
...
def salary_percent_change(self):
return round((self.salary1 - self.salary2) / self.salary2, 2)
The aforementioned is more for illustrative purposes. I understand that there are several issues with it as written. For example, I understand that the SalaryYearOne table does not have a field named salary2 etc. However, I hope this clearly shows my intent. Lastly, for further background the instance of Person will be selected from a ListView and I want to be able to display salary_percent_change as a context variable in my html through my DetailView.
How would you recommend I go about this?
django python-3.x django-models django-templates django-views
django python-3.x django-models django-templates django-views
asked Nov 26 '18 at 0:08
jc4mjc4m
62
asked Nov 26 '18 at 0:08
jc4mjc4m
62
asked Nov 26 '18 at 0:08
jc4mjc4m
62
asked Nov 26 '18 at 0:08
jc4mjc4m
62
asked Nov 26 '18 at 0:08
jc4mjc4m
62
62
add a comment |
add a comment |
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