drop old fields, make use of new fields.

display decimal with 0 properly, non scientific

apps/transactions/models.py

@@ -1,5 +1,25 @@
 from django.db import models
 from django.contrib.auth.models import User
+from decimal import Decimal, Context
+
+class NonscientificDecimalField(models.DecimalField):
+    """ Prevents values from being displayed with E notation, with trailing 0's
+        after the decimal place  truncated. (This causes precision to be lost in
+        many cases, but is more user friendly and consistent for non-scientist
+        users)
+    """
+    def value_from_object(self, obj):
+        def remove_exponent(val):
+            """Remove exponent and trailing zeros.
+               >>> remove_exponent(Decimal('5E+3'))
+               Decimal('5000')
+            """
+            context = Context(prec=self.max_digits)
+            return val.quantize(Decimal(1), context=context) if val == val.to_integral() else val.normalize(context)
+
+        val = super(NonscientificDecimalField, self).value_from_object(obj)
+        if isinstance(val, Decimal):
+            return remove_exponent(val)
 
 # Create your models here.
 class Transaction(models.Model):
@@ -12,15 +32,12 @@ class Transaction(models.Model):
     trade_id = models.CharField(max_length=20, default='MANUAL')
     owner = models.ForeignKey(User, on_delete=models.CASCADE)
     crypto_currency = models.CharField(max_length=10)
-    crypto_amount = models.DecimalField(max_digits=24, decimal_places=10, null=True, blank=True)
-    crypto_fee = models.DecimalField(max_digits=24, decimal_places=10, null=True, blank=True)
-    amount_before_fee = models.DecimalField(max_digits=24, decimal_places=10)
-    amount_after_fee = models.DecimalField(max_digits=24, decimal_places=10)
-    exchange_rate = models.DecimalField(max_digits=24, decimal_places=10)
+    crypto_amount = NonscientificDecimalField(max_digits=24, decimal_places=10, null=True, blank=True)
+    crypto_fee = NonscientificDecimalField(max_digits=24, decimal_places=10, null=True, blank=True)
+    exchange_rate = NonscientificDecimalField(max_digits=24, decimal_places=10)
     fiat_currency = models.CharField(max_length=10)
-    fiat_amount = models.DecimalField(max_digits=24, decimal_places=10, null=True, blank=True)
-    fiat_fee = models.DecimalField(max_digits=24, decimal_places=10, null=True, blank=True)
-    amount = models.DecimalField(max_digits=24, decimal_places=10)
+    fiat_amount = NonscientificDecimalField(max_digits=24, decimal_places=10, null=True, blank=True)
+    fiat_fee = NonscientificDecimalField(max_digits=24, decimal_places=10, null=True, blank=True)
     date_valid = models.DateTimeField('date transfered')
     transaction_type = models.CharField(max_length=1, choices=TRANSACTION_TYPES, default='B')