Only run the form validation stuff if we have a form.

If there is a default value, use it, regardless of whether the form is hidden (this is how the front end works)
  (accomplished by moving the hide_epxression check -> continue stuff below the set default_value code)

crc/services/workflow_service.py

@@ -199,7 +199,8 @@ class WorkflowService(object):
                         task,
                         add_docs_and_forms=True)  # Assure we try to process the documentation, and raise those errors.
                     # make sure forms have a form key
-                    if hasattr(task_api, 'form') and task_api.form is not None and task_api.form.key == '':
+                    if hasattr(task_api, 'form') and task_api.form is not None:
+                        if task_api.form.key == '':
                             raise ApiError(code='missing_form_key',
                                        message='Forms must include a Form Key.',
                                        task_id=task.id,
@@ -315,11 +316,6 @@ class WorkflowService(object):
             #                        task_id='task.id',
             #                        task_name=task.get_name())
 
-            # If the field is hidden it should not produce a value.
-            if field.has_property(Task.FIELD_PROP_HIDE_EXPRESSION):
-                if WorkflowService.evaluate_property(Task.FIELD_PROP_HIDE_EXPRESSION, field, task):
-                    continue
-
             # If we have a default_value, try to set the default
             if field.default_value:
                 try:
@@ -334,6 +330,10 @@ class WorkflowService(object):
             else:
                 form_data[field.id] = None
 
+            # If the field is hidden it should not produce a value.
+            if field.has_property(Task.FIELD_PROP_HIDE_EXPRESSION):
+                if WorkflowService.evaluate_property(Task.FIELD_PROP_HIDE_EXPRESSION, field, task):
+                    continue
 
             # If we are only populating required fields, and this isn't required. stop here.
             if required_only:

tests/data/required_expressions/required_expressions.bpmn

@@ -23,6 +23,11 @@
               <camunda:property id="required_expression" value="not boolean_field" />
             </camunda:properties>
           </camunda:formField>
+          <camunda:formField id="always_set" type="string" defaultValue="&#34;always&#34;">
+            <camunda:properties>
+              <camunda:property id="hide_expression" value="True" />
+            </camunda:properties>
+          </camunda:formField>
         </camunda:formData>
       </bpmn:extensionElements>
       <bpmn:incoming>SequenceFlow_0lvudp8</bpmn:incoming>
@@ -39,6 +44,11 @@ if boolean_field:
   result = required_if_true
 else:
   result = required_if_false
+
+# Note that hidden fields with a default
+# value should always exist.
+if not always_set == "always":
+  should_never_get_here
 </bpmn:script>
     </bpmn:scriptTask>
   </bpmn:process>

tests/workflow/test_workflow_spec_validation_api.py

@@ -177,7 +177,11 @@ class TestWorkflowSpecValidation(BaseTest):
     def test_fields_required_based_on_later_fields_correctly_populates(self):
         """Say you have a form, where the first field is required only if the
         SECOND field is checked true.  This assures such a case will validate and
-        that the variables that should exist (because they are required) do exist."""
+        that the variables that should exist (because they are required) do exist.
+
+        As a bonus test, we also assert that a default field is always present
+        regardless of it's hidden status.
+        """
         self.load_test_spec('empty_workflow', master_spec=True)
         self.create_reference_document()
         errors = self.validate_workflow("required_expressions")