Support saving arbitrary attributes

When an `ITopicRepository` implementation calls `GetAttributes()`, they will now receive arbitrary attributes—i.e., attributes that aren't specified in the `ContentTypeDescriptor` schema, but are defined in the `AttributeValueCollection`. This allows those arbitrary values to be programmatically defined and `Save()`d using the **OnTopic Library**. Previously, this functionality was exclusively available via the SQL database.

Arbitrary attributes present some ambiguity. One source of ambiguity is whether they should be stored as _indexed_ or _extended_ attributes. Currently, most arbitrary attributes defined in the database are stored as _indexed_ attributes, which are easier to update and lookup via SQL. They also tend to be short, so this is an optimal format for them. That said, an arbitrary attribute _could_ be longer than 255—the limit for indexed attributes.

Given this, the `GetAttributes()` will return an arbitrary attribute as _indexed_ if the length is 255 characters or less, and as _extended_ if it's greater than 255 characters. As part of this, I've also made the condtion for returning an attribute more concise.

Finally, this includes a couple of unit tests for validating that arbitrary values are correctly being returned as either indexed or extended attributes via `GetAttributes()`.

This supports Programmatic Support for Arbitrary Attributes (#19)

Author: JeremyCaney

OnTopic.Tests/TopicRepositoryBaseTest.cs

@@ -106,6 +106,48 @@ public void GetAttributes_ExtendedAttributes_ReturnsExtendedAttributes() {
 
     }
 
+    /*==========================================================================================================================
+    | TEST: GET ATTRIBUTES: ARBITRARY ATTRIBUTE WITH SHORT VALUE: RETURNS AS INDEXED ATTRIBUTE
+    \-------------------------------------------------------------------------------------------------------------------------*/
+    /// <summary>
+    ///   Sets an arbitrary (unmatched) attribute on a <see cref="Topic"/> with a value shorter than 255 characters, then
+    ///   ensures that it is returned as an an <i>indexed</i> <see cref="AttributeValue"/> when calling <see
+    ///   cref="TopicRepositoryBase.GetAttributes(Topic, Boolean?, Boolean?)"/>.
+    /// </summary>
+    [TestMethod]
+    public void GetAttributes_ArbitraryAttributeWithShortValue_ReturnsAsIndexedAttributes() {
+
+      var topic                 = TopicFactory.Create("Test", "ContentTypes");
+
+      topic.Attributes.SetValue("ArbitraryAttribute", "Value");
+
+      var attributes            = _topicRepository.GetAttributesProxy(topic, false);
+
+      Assert.IsTrue(attributes.Any(a => a.Key.Equals("ArbitraryAttribute", StringComparison.InvariantCultureIgnoreCase)));
+
+    }
+
+    /*==========================================================================================================================
+    | TEST: GET ATTRIBUTES: ARBITRARY ATTRIBUTE WITH LONG VALUE: RETURNS AS EXTENDED ATTRIBUTE
+    \-------------------------------------------------------------------------------------------------------------------------*/
+    /// <summary>
+    ///   Sets an arbitrary (unmatched) attribute on a <see cref="Topic"/> with a value longer than 255 characters, then
+    ///   ensures that it is returned as an an <see cref="AttributeDescriptor.IsExtendedAttribute"/> when calling <see
+    ///   cref="TopicRepositoryBase.GetAttributes(Topic, Boolean?, Boolean?)"/>.
+    /// </summary>
+    [TestMethod]
+    public void GetAttributes_ArbitraryAttributeWithLongValue_ReturnsAsExtendedAttributes() {
+
+      var topic                 = TopicFactory.Create("Test", "ContentTypes");
+
+      topic.Attributes.SetValue("ArbitraryAttribute", new string('x', 256));
+
+      var attributes            = _topicRepository.GetAttributesProxy(topic, true);
+
+      Assert.IsTrue(attributes.Any(a => a.Key.Equals("ArbitraryAttribute", StringComparison.InvariantCultureIgnoreCase)));
+
+    }
+
     /*==========================================================================================================================
     | TEST: GET UNMATCHED ATTRIBUTES: RETURNS ATTRIBUTES
     \-------------------------------------------------------------------------------------------------------------------------*/

OnTopic/Repositories/TopicRepositoryBase.cs

@@ -502,7 +502,10 @@ protected IEnumerable<AttributeValue> GetAttributes(Topic topic, bool? isExtende
           attribute             = contentType.AttributeDescriptors[key];
         }
 
-        if (attribute != null && (isExtendedAttribute == null || attribute.IsExtendedAttribute == isExtendedAttribute)) {
+        //Add the attribute based on the isExtendedAttribute paramter. Add all parameters if isExtendedAttribute is null. Assume
+        //an attribute is extended if the corresponding attribute descriptor cannot be located and the value is over 255
+        //characters.
+        if (isExtendedAttribute?.Equals(attribute?.IsExtendedAttribute?? attributeValue.Value?.Length > 255)?? true) {
           attributes.Add(attributeValue);
         }