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/Template.fs

@@ -192,7 +192,12 @@ let parser =
             let attrEnc = System.Web.HttpUtility.HtmlAttributeEncode
 
             // OpenGraph tags
-            if app.IsPage || app.IsPost then
+            let doOpenGraph =
+                   (app.WebLog.AutoOpenGraph && (app.IsPage || app.IsPost))
+                || (app.IsPage && Option.isSome app.Page.OpenGraph)
+                || (app.IsPost && Option.isSome app.Posts.Posts[0].OpenGraph)
+
+            if doOpenGraph then
                 let writeOgProp (name, value) =
                     writer.WriteLine $"""{s}<meta property=%s{name} content="{attrEnc value}">"""
                 writeOgProp ("og:title", if app.IsPage then app.Page.Title else app.Posts.Posts[0].Title)
@@ -202,20 +207,7 @@ let parser =
                 |> app.WebLog.AbsoluteUrl
                 |> function url -> writeOgProp ("og:url", url)
                 match if app.IsPage then app.Page.OpenGraph else app.Posts.Posts[0].OpenGraph with
-                | Some props ->
-                    writeOgProp ("og:type", string props.Type)
-                    props.Image.Properties |> Seq.iter writeOgProp
-                    match props.Description with Some desc -> writeOgProp ("og:description", desc) | None -> ()
-                    match props.Determiner  with Some det  -> writeOgProp ("og:determiner",  det)  | None -> ()
-                    match props.Locale      with Some loc  -> writeOgProp ("og:locale",      loc)  | None -> ()
-                    match props.LocaleAlternate with
-                    | Some alt -> alt |> List.iter (fun it -> writeOgProp ("og:locale:alternate", it))
-                    | None -> ()
-                    match props.Audio with Some audio -> audio.Properties |> Seq.iter writeOgProp | None -> ()
-                    match props.Video with Some video -> video.Properties |> Seq.iter writeOgProp | None -> ()
-                    match props.Other with
-                    | Some oth -> oth |> List.iter (fun it -> writeOgProp (it.Name, it.Value))
-                    | None -> ()
+                | Some props -> props.Properties |> Seq.iter writeOgProp
                 | None -> ()
 
             writer.WriteLine $"""{s}<meta name=generator content="{app.Generator}">"""

src/MyWebLog/Views/WebLog.fs

@@ -795,6 +795,13 @@ let webLogSettings
                             selectField [] (nameof model.Uploads) "Default Upload Destination" model.Uploads uploads
                                         string string []
                         ]
+                        div [ _class "col-12 col-md-6 offset-md-3 col-xl-4 offset-xl-4" ] [
+                            checkboxSwitch [] (nameof model.AutoOpenGraph) "Auto-Add OpenGraph Properties"
+                                           model.AutoOpenGraph []
+                            span [ _class "form-text fst-italic" ] [
+                                raw "Adds title, site name, and permalink to all pages and posts"
+                            ]
+                        ]
                     ]
                     div [ _class "row pb-3" ] [
                         div [ _class "col text-center" ] [