Job code price history

Using Django
1

Hi guy, question…

Gat a crew code-price tracker implemented using Django and MySql
Job code change in a few weeks meaning certain task pay more while other pay less, what would be the easiest and best way to implement price history. Job codes are stored in a separate table from jobs.
Added code_price_history = FieldHistoryTracker(['code_price']) back in the day when app developed but not sure how to use it ::
If I update the code price with new price it will effect the entire year of job and not just the jobs after certain date, need some advice please.

class Job(models.Model):

    user = models.ForeignKey(
        Tech, on_delete=models.DO_NOTHING)

    JOB_TYPES = (
        ('wo', 'Work Order'),
        ('sc', 'Service Call')
    )

    work_order = models.CharField(max_length=64)
    job_type = models.CharField(max_length=16, choices=JOB_TYPES)
    address = models.CharField(max_length=256)
    customer_name = models.CharField(max_length=256)
    note = models.TextField(null=True, blank=True)
    codes = models.ManyToManyField(JobCode, through='JobCode')

    job_start = models.TimeField(null=True, blank=True)
    job_end = models.TimeField(null=True, blank=True)

    processed = models.BooleanField(null=True, blank=True)

    created_at = CustomDateTimeField(auto_now_add=True)
    updated_at = CustomDateTimeField(auto_now=True)


class JobCode(models.Model):
    code = models.CharField(max_length=4)
    code_type = models.CharField(max_length=32, default= '')
    code_description = models.CharField(max_length=256, default='')
    code_price = models.DecimalField(default=0, max_digits=6, decimal_places=2)
    code_link = models.URLField(max_length=256, default='')

    code_price_history = FieldHistoryTracker(['code_price'])
2

I am no sure what do you want to achieve, but if what you want is to keep track of the changes in your instance you cold use Django Simple History.

3

For example job code 565 paid $25 but from November 1 it will pay $26.50
All the contractor when they check their code tracker will get inaccurate sum for the year to date payouts as the previously submitted work orders code price will now reflect $26.50 even though the new price only effective from November 1st and onwards.

4

What we do for historical data is create a “History” table with a small number of key fields and one JSON field. We create the JSON field with all the data needed to recreate a particular invoice. There are no foreign keys or references to anything else. That way, those invoices remain static regardless of any changes to the rest of the system.

5

I think you should make other field with that information, one for the actual “market price” and another for the price you will pay to the contractor.

6

Almost every contractor got different rate, it was easy as I give each of them a rate %70-%95 what’s linked to the user profile than total * rate give them them payout.
I think this code need to look for the code_price_history (somehow)

def calculate_total(self):
        sum = 0
        for match in self.jobtbc_set.all(): 
            sum += round_half_up(float(match.posted_price * match.quantity) * (self.user.ratio / 100),2)  
        return sum