Specify the values parameter value for Boolean. Increase documentatio…

…n to give a hint as to how this will be used by Studio.

xblock/core.py

@@ -67,9 +67,9 @@ class ModelType(object):
       `default` : static value to default to if not otherwise specified (defaults to None)
       `scope` : the scope in which this field class is used (defaults to Scope.content)
       `display_name` : the display name for the field class, suitable for presenting in a GUI (defaults to name of class)
-      `values` : for field classes with a finite number of valid values, provides the ability to specify the set of
+      `values` : for field classes with a known set of valid values, provides the ability to explicitly specify the
                valid values. This can be specified as either a static return value, or a function that generates
-               the valid values.
+               the valid values. For example formats, see the values property definition.
     """
 
     def __init__(self, help=None, default=None, scope=Scope.content, display_name=None,
@@ -92,9 +92,15 @@ def name(self):
     @property
     def values(self):
         """
-        Returns the valid values for this class.
+        Returns the valid values for this class. This is useful for representing possible values in a UI.
 
-        If this field class does not define a finite number of valid values, this method will return None.
+        Example formats:
+            '[1, 2, 3]' : a finite set of elements
+            '[{"display_name": "Always", "value": "always"}, {"display_name": "Past Due", "value": "past_due"}] :
+                a finite set of elements where the display names differ from the values
+            '{"min" : 0 , "max" : 10, "step": .1}' : a range for floating point numbers with increment .1
+
+        If this field class does not define a set of valid values, this method will return None.
         """
         if callable(self._values):
             return self._values()
@@ -226,7 +232,12 @@ class Float(ModelType):
 
 
 class Boolean(ModelType):
-    pass
+    """
+    A field class for representing a Boolean. This class has the values property predefined.
+    """
+    def __init__(self, help=None, default=None, scope=Scope.content, display_name=None,
+                 values=({'display_name': "True", "value": True}, {'display_name': "False", "value": False})):
+        super( Boolean, self ).__init__(help, default, scope, display_name, values)
 
 
 class Object(ModelType):

xblock/test/test_core.py

@@ -407,6 +407,9 @@ def test_field_display_name():
     attempts._name = "max_problem_attempts"
     assert_equals("Maximum Problem Attempts", attempts.display_name)
 
+    boolean_field = Boolean(display_name= "boolean field")
+    assert_equals("boolean field", boolean_field.display_name)
+
     class TestNamespace(Namespace):
         field_x = List(display_name="Field Known as X")
 
@@ -425,3 +428,15 @@ def test_values():
 
     # default if nothing specified
     assert_equals(None, String().values)
+
+    # Test boolean, which by default has values specified
+    test_field = Boolean()
+    assert_equals(({'display_name': "True", "value": True}, {'display_name': "False", "value": False}), test_field.values)
+
+    # Test that you can override the Boolean default for values
+    test_field = Boolean(values=[False])
+    assert_equals([False], test_field.values)
+
+    # Test the format expected for integers
+    test_field = Integer(values={"min": 1, "max" : 100})
+    assert_equals({"min": 1, "max" : 100}, test_field.values)