CODEWITHSUNDEEP
djangodjango-modelsdjango-validation
Uribe2304
Uribe2304

Reputation: 51

Validate if a field value is greater than another model´s field

I have problems with the parameters, when The validator is written used this way:

    cantidadusada = models.DecimalField(max_digits=50, decimal_places=3,validators=[insumo_existencias])

It automatically gets the value of the respective field in the validator.py

def insumo_existencias(value):
#Por alguna razon, me esta devolviendo un string
insumo = models.Insumo.objects.get(id=1)

if (insumo.cantidadexistencias < value):
    raise ValidationError(
        _('Error no hay existencias suficientes'),
    )

So, I just have to call it value and that´s it, but when I want to pass another parameter,the function does not longer get the value of the field. I tried this:

  cantidadusada = models.DecimalField(max_digits=50, decimal_places=3,validators=[insumo_existencias(cantidadusada,idinsumo)])

It is not working. Obviosuly the validator function was changed to acept to parameters

Upvotes: 1

Views: 770

Answers (2)

Tabasss_e
Tabasss_e

Reputation: 1

you can pass multiple parameters to a validator by creating a custom validator function or class.

Using a Function

   from django.core.exceptions import ValidationError

   def custom_validator(value, param1, param2):
       if not some_condition(value, param1, param2):
           raise ValidationError(f'{value} failed the validation with {param1} and {param2}')

Since Django validators only accept a single argument (value), you need to use a lambda or a partial function to pass additional parameters:

   from functools import partial

   class MyModel(models.Model):
       my_field = models.CharField(max_length=100, validators=[partial(custom_validator, param1='value1', param2='value2')])

but using the save function of the class is going to let you do some logic before saving it to the database

Upvotes: 0

Tabasss_e
Tabasss_e

Reputation: 1

You can change it in save function:

def save(self,*args, **kwargs):
    if (insumo.cantidadexistencias > value):
       super().save(*args, **kwargs)
    else:
       pass
       #do not save it!and raise error

Upvotes: 0

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