external_data.rb in vault-tree-0.3.3

- old
+ new

@@ -1,13 +1,32 @@
 module VaultTree
   class ExternalData < Keyword
 
     def evaluate
+      check_for_external_data
       contract.external_data(id)
     end
 
     def id
       vault.id
+    end
+
+    private
+
+    def check_for_external_data
+      raise(Exceptions::MissingExternalData) if missing_external_data?
+    end
+
+    def missing_external_data?
+      nil_external_data? || empty_external_data?
+    end
+
+    def nil_external_data?
+      contract.external_data_hash.nil?
+    end
+
+    def empty_external_data?
+      contract.external_data_hash.empty?
     end
 
   end
 end