enforce max amount on sith account

counter/fields.py

@@ -1,22 +1,67 @@
 from decimal import Decimal
 
 from django.conf import settings
+from django.core import checks
+from django.core.validators import MaxValueValidator, MinValueValidator
 from django.db import models
+from django.utils.functional import cached_property
 
 
 class CurrencyField(models.DecimalField):
     """Custom database field used for currency."""
 
-    def __init__(self, *args, **kwargs):
-        kwargs["max_digits"] = 12
-        kwargs["decimal_places"] = 2
-        super().__init__(*args, **kwargs)
+    def __init__(
+        self, verbose_name=None, name=None, min_value=None, max_value=None, **kwargs
+    ):
+        kwargs.update({"max_digits": 12, "decimal_places": 2})
+        self.min_value = min_value
+        self.max_value = max_value
+        super().__init__(verbose_name, name, **kwargs)
 
     def to_python(self, value):
         if value is None:
             return None
         return super().to_python(value).quantize(Decimal("0.01"))
 
+    @cached_property
+    def validators(self):
+        res = []
+        if self.max_value:
+            res.append(MaxValueValidator(self.max_value))
+        if self.min_value:
+            res.append(MinValueValidator(self.min_value))
+        return [*super().validators, *res]
+
+    def check(self, **kwargs):
+        errors = super().check(**kwargs)
+        for name, val in ("min_value", self.min_value), ("max_value", self.max_value):
+            if not val:
+                continue
+            try:
+                float(val)
+            except ValueError:
+                errors.append(
+                    checks.Error(
+                        f"CurrencyField.{name} must be a valid float",
+                        obj=self,
+                        id="sith.E001",
+                    )
+                )
+        return errors
+
+    def formfield(self, **kwargs):
+        return super().formfield(
+            **{"min_value": self.min_value, "max_value": self.max_value, **kwargs}
+        )
+
+    def deconstruct(self):
+        name, path, args, kwargs = super().deconstruct()
+        if self.min_value is not None:
+            kwargs["min_value"] = self.min_value
+        if self.max_value is not None:
+            kwargs["max_value"] = self.max_value
+        return name, path, args, kwargs
+
 
 if settings.TESTING:
     from model_bakery import baker