kirpit · December 16, 2015 16:08 · Aug 21, 2013 · Apr 30, 2013 · Apr 29, 2013 · Apr 26, 2013
diff --git a/fields_dict.py b/fields_dict.py
@@ -7,8 +7,9 @@ class FieldsDict(dict):
     FIELDS = None
     REQUIRED = None
 
-    def __init__(self, seq, **kwargs):
+    def __init__(self, seq=None, **kwargs):
         # create a single dict
+        seq = seq or {}
         mapping = dict(seq, **kwargs)
         # make sure all fields are expected
         try:
@@ -20,14 +21,13 @@ def __init__(self, seq, **kwargs):
         # and check the required fields
         if self.REQUIRED:
             try:
-                req = next(r for r in self.REQUIRED if r[0] not in mapping)
+                req = next(r for r in self.REQUIRED if r not in mapping)
             except StopIteration:
                 pass
             else:
-                raise ValueError(req[1])
+                raise ValueError("The field '%s' is required" % req)
         super(FieldsDict, self).__init__(mapping)
 
-
 # use as:
 class Person(FieldsDict):
     FIELDS = (
@@ -39,16 +39,16 @@ class Person(FieldsDict):
         'birthday',
     )
     REQUIRED = (
-        ('title', "Title is required"),
-        ('first_name', "First name is required"),
-        ('last_name', "Last name is required"),
+        'title',
+        'first_name',
+        'last_name',
     )
 
 
-# should give ValueError("Title is required")
+# should give ValueError("The field 'title' is required")
 me = Person(first_name='Roy')
 
-# should give ValueError("Last name is required")
+# should give ValueError("The field 'last_name' is required")
 me = Person({'title': 'MR', 'first_name': 'Roy'})
 
 # should give ValueError("The field 'level' was not expected")

diff --git a/fields_dict.py b/fields_dict.py
@@ -8,8 +8,8 @@ class FieldsDict(dict):
     REQUIRED = None
 
     def __init__(self, seq, **kwargs):
-        # clear empty fields
-        mapping = dict([(k, v) for k, v in dict(seq, **kwargs).iteritems()])
+        # create a single dict
+        mapping = dict(seq, **kwargs)
         # make sure all fields are expected
         try:
             unexpected = next(key for key in mapping if key not in self.FIELDS)

diff --git a/fields_dict.py b/fields_dict.py
@@ -9,7 +9,7 @@ class FieldsDict(dict):
 
     def __init__(self, seq, **kwargs):
         # clear empty fields
-        mapping = dict([(k, v) for k, v in dict(seq, **kwargs).iteritems() if v])
+        mapping = dict([(k, v) for k, v in dict(seq, **kwargs).iteritems()])
         # make sure all fields are expected
         try:
             unexpected = next(key for key in mapping if key not in self.FIELDS)

diff --git a/gistfile1.py → fields_dict.py b/gistfile1.py → fields_dict.py
diff --git a/gistfile1.py b/gistfile1.py
@@ -0,0 +1,60 @@
+#! /usr/bin/env python
+from abc import ABCMeta
+
+
+class FieldsDict(dict):
+    __metaclass__ = ABCMeta
+    FIELDS = None
+    REQUIRED = None
+
+    def __init__(self, seq, **kwargs):
+        # clear empty fields
+        mapping = dict([(k, v) for k, v in dict(seq, **kwargs).iteritems() if v])
+        # make sure all fields are expected
+        try:
+            unexpected = next(key for key in mapping if key not in self.FIELDS)
+        except StopIteration:
+            pass
+        else:
+            raise ValueError("The field '%s' was not expected" % unexpected)
+        # and check the required fields
+        if self.REQUIRED:
+            try:
+                req = next(r for r in self.REQUIRED if r[0] not in mapping)
+            except StopIteration:
+                pass
+            else:
+                raise ValueError(req[1])
+        super(FieldsDict, self).__init__(mapping)
+
+
+# use as:
+class Person(FieldsDict):
+    FIELDS = (
+        'title',
+        'first_name',
+        'last_name',
+        'email',
+        'phone',
+        'birthday',
+    )
+    REQUIRED = (
+        ('title', "Title is required"),
+        ('first_name', "First name is required"),
+        ('last_name', "Last name is required"),
+    )
+
+
+# should give ValueError("Title is required")
+me = Person(first_name='Roy')
+
+# should give ValueError("Last name is required")
+me = Person({'title': 'MR', 'first_name': 'Roy'})
+
+# should give ValueError("The field 'level' was not expected")
+me = Person({'level': 'PRO', 'first_name': 'Roy'})
+
+# should be fine
+me = Person({'title': 'MR', 'first_name': 'Roy', 'last_name': 'Enjoy', 'email': '[email protected]'})
+# or that is fine too
+me = Person(title='MR', first_name='Roy', last_name='Enjoy', phone=123456)