Bug: Error if product group is not set

[andreheuer]

When requesting a product for which the product group is not set, an exception is raised by pygrocy.
Following example from the demo instance:

from pygrocy import Grocy
grocy = Grocy('https://demo.grocy.info','',port=443)
product = grocy.product(27)

This raises the following exception:

Traceback (most recent call last):
  File "/mnt/d/Code/grocy-openfoodfacts/test.py", line 5, in <module>
    product = grocy.product(27)
  File "/home/andreheuer/.local/lib/python3.8/site-packages/pygrocy/grocy.py", line 96, in product
    resp = self._api_client.get_product(product_id)
  File "/home/andreheuer/.local/lib/python3.8/site-packages/pygrocy/grocy_api_client.py", line 349, in get_product
    return ProductDetailsResponse(**parsed_json)
  File "pydantic/main.py", line 406, in pydantic.main.BaseModel.__init__
pydantic.error_wrappers.ValidationError: 1 validation error for ProductDetailsResponse
product -> product_group_id
  value is not a valid integer (type=type_error.integer)

[SebRut]

I guess this is related to this grocy/grocy#1683.
The API response was changed back to string and so the pygrocy code has to be fixed too.

[blue-hound]

Hi,
I'd do a pull request for this but my Python isn't great and I don't know if this is the preferred way of fixing this.

I fixed the product_group_id problem by importing validator from pydantic and adding the second code block to the end of the ProductData definition. Not sure why the definition doesn't work that already exists but as I said, my Python is terrible.

from pydantic import BaseModel, Field, validator

validator('product_group_id', pre=True)            
def blank_string(value, field):                     
   if value == "":                                 
      return None                                  
   return value

[andreheuer]

fixed with #234