To compute the start date based on the end date and allocated hours in Odoo, you can use Python's datetime module to handle date and time calculations. In Odoo 16, you would generally use datetime.timedelta for this kind of calculation. The error you encountered suggests there's an issue with the way you're trying to subtract time from a date.

Here's how you can correctly implement this in your model:

1. Ensure datetime Module Import:
   • Import datetime and timedelta at the beginning of your Python file.
2. Correct Computation Method:
   • Use timedelta to subtract hours from the end date. The fields.Datetime class in Odoo doesn't directly support operations like subtraction, so you need to convert the datetime field to a Python datetime object, perform the calculation, and then set the result back to the Odoo field.

Here’s how you can update your _compute_shift_start method:

pythonCopy codefrom datetime import datetime, timedelta
from odoo import models, fields

class PlanningSlot(models.Model):
    _name = 'planning.slot'
    _description = 'Planning Slot'

    x_studio_studio_shift_start = fields.Datetime(compute='_compute_shift_start', store=True)
    x_studio_studio_shift_end = fields.Datetime(string='End Date')
    allocated_hours = fields.Float(string='Allocated Hours')

    def _compute_shift_start(self):
        for record in self:
            if record.x_studio_studio_shift_end and record.allocated_hours:
                end_date = fields.Datetime.from_string(record.x_studio_studio_shift_end)
                allocated_time = timedelta(hours=record.allocated_hours)
                start_date = end_date - allocated_time
                record.x_studio_studio_shift_start = fields.Datetime.to_string(start_date)
            else:
                record.x_studio_studio_shift_start = record.x_studio_studio_shift_end

Explanation:

1. Imports:
   • timedelta is used to create a time difference of the allocated hours.
2. Conversion to datetime:
   • fields.Datetime.from_string(record.x_studio_studio_shift_end) converts the Odoo datetime field to a Python datetime object.
   • fields.Datetime.to_string(start_date) converts the Python datetime object back to an Odoo-compatible datetime string.
3. Subtracting Time:
   • end_date - allocated_time performs the date-time subtraction to compute the start date.

Additional Notes:

• Ensure that store=True is used in the field definition if you want to persist computed values in the database.
• If the allocated_hours can be a fraction (e.g., 8.5 hours), ensure that your model's field type is set to Float for allocated_hours.

This approach should work for your requirement to compute the start date by subtracting allocated hours from the end date. Let me know if you encounter any further issues!

This does not work.

Hi,

Have a look at this:

@api.depends( 'x_studio_studio_shift_end' , 'allocated_hours' ) 

def _compute_shift_start ( self ): 

for record in self: 

​if record.x_studio_studio_shift_end and record.allocated_hours: 

      ​ ​# Calculate start date by subtracting allocated hours from end date record.

​​x_studio_studio_shift_start = record. x_studio_studio_shift_end - timedelta(hours=record.allocated_hours)  ​

​else : 

​ ​record.x_studio_studio_shift_start = record.x_studio_studio_shift_end ​

Thanks & Regards,