Move OpenGraph property generation to models (#52)

- Add auto-OpenGraph field to web log
- Only generate properties for posts/pages without them if this flag is set
- Set flag to yes on v3 database migration
- Add JSON converter for OpenGraph type
- Add tests for models

src/MyWebLog.Tests/Data/ConvertersTests.fs

@@ -90,7 +90,7 @@ let explicitRatingConverterTests = testList "ExplicitRatingConverter" [
     }
 ]
 
-/// Unit tests for the MarkupText type
+/// Unit tests for the MarkupTextConverter type
 let markupTextConverterTests = testList "MarkupTextConverter" [
     let opts = JsonSerializerSettings()
     opts.Converters.Add(MarkupTextConverter())
@@ -104,6 +104,20 @@ let markupTextConverterTests = testList "MarkupTextConverter" [
     }
 ]
 
+/// Unit tests for the OpenGraphTypeConverter type
+let openGraphTypeConverterTests = testList "OpenGraphTypeConverter" [
+    let opts = JsonSerializerSettings()
+    opts.Converters.Add(OpenGraphTypeConverter())
+    test "succeeds when serializing" {
+        let after = JsonConvert.SerializeObject(VideoTvShow, opts)
+        Expect.equal after "\"video.tv_show\"" "OpenGraph type serialized incorrectly"
+    }
+    test "succeeds when deserializing" {
+        let after = JsonConvert.DeserializeObject<OpenGraphType>("\"book\"", opts)
+        Expect.equal after Book "OpenGraph type deserialized incorrectly"
+    }
+]
+
 /// Unit tests for the PermalinkConverter type
 let permalinkConverterTests = testList "PermalinkConverter" [
     let opts = JsonSerializerSettings()
@@ -257,6 +271,7 @@ let configureTests = test "Json.configure succeeds" {
     Expect.hasCountOf ser.Converters 1u (has typeof<CustomFeedSourceConverter>) "Custom feed source converter not found"
     Expect.hasCountOf ser.Converters 1u (has typeof<ExplicitRatingConverter>) "Explicit rating converter not found"
     Expect.hasCountOf ser.Converters 1u (has typeof<MarkupTextConverter>) "Markup text converter not found"
+    Expect.hasCountOf ser.Converters 1u (has typeof<OpenGraphTypeConverter>) "OpenGraph type converter not found"
     Expect.hasCountOf ser.Converters 1u (has typeof<PermalinkConverter>) "Permalink converter not found"
     Expect.hasCountOf ser.Converters 1u (has typeof<PageIdConverter>) "Page ID converter not found"
     Expect.hasCountOf ser.Converters 1u (has typeof<PodcastMediumConverter>) "Podcast medium converter not found"
@@ -282,6 +297,7 @@ let all = testList "Converters" [
     customFeedSourceConverterTests
     explicitRatingConverterTests
     markupTextConverterTests
+    openGraphTypeConverterTests
     permalinkConverterTests
     pageIdConverterTests
     podcastMediumConverterTests