fix(meta): detail types and metadata endpoint carry unrated as null

MovieDetail and SeriesDetail normalise TMDB's vote_average: 0 to None
like the persisted structs (#156), and #146's metadata endpoint passes
the Option through so no surface reports 0.0 as a rating. vote_count is
untouched.

crates/arr-api/src/metadata.rs

@@ -46,7 +46,9 @@ pub struct MovieMetadata {
     pub status: String,
     pub poster_path: Option<String>,
     pub backdrop_path: Option<String>,
-    pub vote_average: f64,
+    /// TMDB's rating when votes exist; an unrated title is `null`, never `0.0`
+    /// (#156).
+    pub vote_average: Option<f64>,
     pub vote_count: u32,
     pub homepage: Option<String>,
     /// §9.6 links out to `IMDb` for movies.
@@ -68,7 +70,9 @@ pub struct SeriesMetadata {
     pub status: String,
     pub poster_path: Option<String>,
     pub backdrop_path: Option<String>,
-    pub vote_average: f64,
+    /// TMDB's rating when votes exist; an unrated title is `null`, never `0.0`
+    /// (#156).
+    pub vote_average: Option<f64>,
     pub vote_count: u32,
     pub homepage: Option<String>,
     /// §9.6 links out to TVDB for series.
@@ -366,7 +370,7 @@ mod tests {
                 "genres": [{"id": 18, "name": "Drama"}],
                 "backdrop_path": "/eMhDKZscBd07OLpAeeAyu3N3U8c.jpg",
                 "poster_path": "/uKvVjHNqB5VmOrdxqAt2F7J78ED.jpg",
-                "vote_average": 8.5,
+                "vote_average": 0.0,
                 "vote_count": 2_911,
                 "homepage": "",
                 "status": "Returning Series",
@@ -397,6 +401,11 @@ mod tests {
 
         assert_eq!(body["tmdb_id"], 82_728);
         assert_eq!(body["tvdb_id"], 392_256);
+        // TMDB reports vote_average: 0 for an unrated title (#156): it leaves
+        // as null, never as a rating of zero. The movie case covers the rated
+        // pass-through.
+        assert_eq!(body["vote_average"], serde_json::Value::Null);
+        assert_eq!(body["vote_count"], 2_911);
         // TMDB sends a list of episode lengths; the API reports one runtime.
         assert_eq!(body["runtime"], 55);
         assert_eq!(body["status"], "Returning Series");

crates/arr-meta/src/model.rs

@@ -213,8 +213,8 @@ pub struct Video {
 /// `append_to_response`, served through the same cache as everything else;
 /// nothing here is persisted.
 ///
-/// No float fields are involved in equality except `vote_average`, so this is
-/// `PartialEq` only.
+/// No float fields are involved in equality except [`MovieDetail::vote_average`],
+/// so this is `PartialEq` only.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 pub struct MovieDetail {
     pub tmdb_id: u32,
@@ -223,7 +223,9 @@ pub struct MovieDetail {
     pub genres: Vec<Genre>,
     pub backdrop_path: Option<String>,
     pub poster_path: Option<String>,
-    pub vote_average: f64,
+    /// TMDB's rating when votes exist; zero is normalised away like
+    /// [`Movie::vote_average`].
+    pub vote_average: Option<f64>,
     pub vote_count: u32,
     pub homepage: Option<String>,
     pub status: String,
@@ -244,7 +246,9 @@ pub struct SeriesDetail {
     pub genres: Vec<Genre>,
     pub backdrop_path: Option<String>,
     pub poster_path: Option<String>,
-    pub vote_average: f64,
+    /// TMDB's rating when votes exist; zero is normalised away like
+    /// [`Movie::vote_average`].
+    pub vote_average: Option<f64>,
     pub vote_count: u32,
     pub homepage: Option<String>,
     pub status: String,
@@ -771,7 +775,7 @@ impl From<RawMovieDetail> for MovieDetail {
                 .collect(),
             backdrop_path: non_empty(raw.backdrop_path),
             poster_path: non_empty(raw.poster_path),
-            vote_average: raw.vote_average,
+            vote_average: rating(raw.vote_average),
             vote_count: raw.vote_count,
             homepage: non_empty(raw.homepage),
             status: raw.status,
@@ -799,7 +803,7 @@ impl From<RawSeriesDetail> for SeriesDetail {
                 .collect(),
             backdrop_path: non_empty(raw.backdrop_path),
             poster_path: non_empty(raw.poster_path),
-            vote_average: raw.vote_average,
+            vote_average: rating(raw.vote_average),
             vote_count: raw.vote_count,
             homepage: non_empty(raw.homepage),
             status: raw.status,

crates/arr-meta/tests/tmdb.rs

@@ -613,7 +613,7 @@ async fn movie_detail_parses_the_rich_fields() {
     assert_eq!(movie.genres[0].name, "Science Fiction");
     assert!(movie.poster_path.is_some());
     assert!(movie.backdrop_path.is_some());
-    assert!((movie.vote_average - 8.152).abs() < f64::EPSILON);
+    assert_eq!(movie.vote_average, Some(8.152));
     assert_eq!(movie.vote_count, 6_249);
     assert_eq!(movie.homepage.as_deref(), Some("https://www.dunemovie.com"));
     assert_eq!(movie.status, "Released");