wrap __format__ method of _value and enforce Decimal() type in __init__

Author: Daniel Hiepler

drafthorse/models/elements.py

@@ -158,13 +158,16 @@ def from_etree(self, root, strict=True):
 class DecimalElement(StringElement):
     def __init__(self, namespace, tag, value=None):
         super().__init__(namespace, tag)
-        self._value = value
+        self._value = Decimal(value) if value is not None else None
 
     def to_etree(self):
         node = self._etree_node()
         node.text = str(self._value) if self._value is not None else ""
         return node
 
+    def __format__(self, fmt):
+        return self._value.__format__(fmt)
+
     def __str__(self):
         return str(self._value)