Add Fluid where filter, fix slug (#47)

- Fix issue with path base and logon redirects

src/MyWebLog/Template.fs

@@ -172,6 +172,21 @@ let options () =
                 |> Option.defaultValue $"-- {name} not found --"
             |> sValue)
 
+    // A filter to search through a collection of objects for a matching property
+    it.Filters.AddFilter("where",
+        fun input args ctx ->
+            let name = args.At(0).ToStringValue()
+            let value = args.At(1).ToStringValue()
+            input.Enumerate(ctx)
+            |> Seq.filter (fun it ->
+                let theItem = it.ToObjectValue()
+                match theItem.GetType().GetProperties() |> Array.tryFind (fun x -> x.Name = name) with
+                | Some pi -> pi.GetValue(theItem) = value
+                | None -> false)
+            |> Seq.toArray
+            |> ArrayValue :> FluidValue
+            |> VTask)
+
     it
 
 open Giraffe.Htmx.Common
@@ -234,11 +249,11 @@ let parser =
                 writer.WriteLine $"""{s}<link rel=canonical href="{app.WebLog.AbsoluteUrl Permalink.Empty}">"""
 
             if app.WebLog.Rss.IsCategoryEnabled && app.IsCategoryHome then
-                let slug = context.AmbientValues["slug"] :?> string
+                let slug = (context.Model.ToObjectValue() :?> AppViewContext).Slug
                 writer.WriteLine(feedLink app.WebLog.Name $"category/{slug}/{app.WebLog.Rss.FeedName}")
 
             if app.WebLog.Rss.IsTagEnabled && app.IsTagHome then
-                let slug = context.AmbientValues["slug"] :?> string
+                let slug = (context.Model.ToObjectValue() :?> AppViewContext).Slug
                 writer.WriteLine(feedLink app.WebLog.Name $"tag/{slug}/{app.WebLog.Rss.FeedName}")
 
             if app.IsPost then
@@ -287,7 +302,7 @@ let parser =
                 "</ul>"
             }
             |> Seq.iter writer.WriteLine
-            ok())
+            ok ())
 
     it