python django fields and row calculation

[sum abiut]

Hi,

I am working on an leave management system and I am having a some difficulties trying to figure out how to accomplished this scenario.

for example i have a table of.

when a user apply for a leave i want to get the previous total_leave_balance of the applicant and minus his/her current num_days and assign the result to be the total_leave_balance. Please advise what would be the best way to approach this.

username	first_name	second_name	num_days	leave_entitlement	beginning_bal	Total_leave_balance
jtom	james	tom	3	12	23	20
tjohn	tom	john	2	2	5	7
atom	anna	tom	3	21	2
jtom	james	tom	3	4	2
atom	anna	tom	3	3	5

cheers,

[Lachlan Musicman]

Depends on your models, but write a small function that returns the balance?

def balance(self):
    return self.entitlement - self.num_days

(for instance)

L.

------
The most dangerous phrase in the language is, "We've always done it this way."

- Grace Hopper

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[sum abiut]

Thank for taking your time to respond. my problem is automating that, for example when a user apply for a leave i want the system to calculate and update the total balance automatically. But Since a user can apply for a leave more that once which mean a user can have more that one record of leave application on the database. My problem is having to figure out when was the last time that the user has launch his/her leave application so that i can minus num_days from the that total balance.

thanks

 

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[Lachlan Musicman]

Well, if it's on the user model as a function, then it will happen as soon as you call it.

If they can have mulitple applications in process, then you will need to program your function(s) to account for that.

As they say "there's more than one way to do it".

You could add a "remaining days" var to the user model and store the info in there secretly.

You could get the function to programmatically work through the applications for the user in the order in which they have been received?
...

cheers

L.

------
The most dangerous phrase in the language is, "We've always done it this way."

- Grace Hopper

To view this discussion on the web visit https://groups.google.com/d/msgid/django-users/CAPCf-y5CNSJacdxNqL%2Bxwa0LkjAvsoT%3D1%2B384hNJ0KxfhGi87A%40mail.gmail.com.

[sum abiut]

Thanks heaps this should get me started

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[ijazz jazz]

In short, a model's manager is an object through which Django models perform ... (For row-level functionality – i.e., functions that act on a single instance of a model object ... This has a single method, title_count() , which does the calculation.

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