h-data: Refactor the Diesel helper traits to use Associated Types.

hammond-data/src/models/episode.rs

@@ -31,10 +31,12 @@ pub struct Episode {
     podcast_id: i32,
 }
 
-impl Save<Episode, DataError> for Episode {
+impl Save<Episode> for Episode {
+    type Error = DataError;
+
     /// Helper method to easily save/"sync" current state of self to the
     /// Database.
-    fn save(&self) -> Result<Episode, DataError> {
+    fn save(&self) -> Result<Episode, Self::Error> {
         let db = connection();
         let tempdb = db.get()?;
 
@@ -224,10 +226,12 @@ impl From<Episode> for EpisodeWidgetQuery {
     }
 }
 
-impl Save<usize, DataError> for EpisodeWidgetQuery {
+impl Save<usize> for EpisodeWidgetQuery {
+    type Error = DataError;
+
     /// Helper method to easily save/"sync" current state of self to the
     /// Database.
-    fn save(&self) -> Result<usize, DataError> {
+    fn save(&self) -> Result<usize, Self::Error> {
         use schema::episode::dsl::*;
 
         let db = connection();
@@ -363,10 +367,12 @@ pub struct EpisodeCleanerQuery {
     played: Option<i32>,
 }
 
-impl Save<usize, DataError> for EpisodeCleanerQuery {
+impl Save<usize> for EpisodeCleanerQuery {
+    type Error = DataError;
+
     /// Helper method to easily save/"sync" current state of self to the
     /// Database.
-    fn save(&self) -> Result<usize, DataError> {
+    fn save(&self) -> Result<usize, Self::Error> {
         use schema::episode::dsl::*;
 
         let db = connection();

hammond-data/src/models/mod.rs

@@ -30,22 +30,30 @@ pub enum IndexState<T> {
     NotChanged,
 }
 
-pub trait Insert<T, E> {
+pub trait Insert<T> {
-    fn insert(&self) -> Result<T, E>;
+    type Error;
+
+    fn insert(&self) -> Result<T, Self::Error>;
 }
 
-pub trait Update<T, E> {
+pub trait Update<T> {
-    fn update(&self, i32) -> Result<T, E>;
+    type Error;
+
+    fn update(&self, i32) -> Result<T, Self::Error>;
 }
 
 // This might need to change in the future
-pub trait Index<T, E>: Insert<T, E> + Update<T, E> {
+pub trait Index<T>: Insert<T> + Update<T> {
-    fn index(&self) -> Result<T, E>;
+    type Error;
+
+    fn index(&self) -> Result<T, <Self as Index<T>>::Error>;
 }
 
 /// FIXME: DOCS
-pub trait Save<T, E> {
+pub trait Save<T> {
+    /// The Error type to be returned.
+    type Error;
     /// Helper method to easily save/"sync" current state of a diesel model to
     /// the Database.
-    fn save(&self) -> Result<T, E>;
+    fn save(&self) -> Result<T, Self::Error>;
 }

hammond-data/src/models/new_episode.rs

@@ -43,7 +43,9 @@ impl From<NewEpisodeMinimal> for NewEpisode {
     }
 }
 
-impl Insert<(), DataError> for NewEpisode {
+impl Insert<()> for NewEpisode {
+    type Error = DataError;
+
     fn insert(&self) -> Result<(), DataError> {
         use schema::episode::dsl::*;
         let db = connection();
@@ -58,7 +60,9 @@ impl Insert<(), DataError> for NewEpisode {
     }
 }
 
-impl Update<(), DataError> for NewEpisode {
+impl Update<()> for NewEpisode {
+    type Error = DataError;
+
     fn update(&self, episode_id: i32) -> Result<(), DataError> {
         use schema::episode::dsl::*;
         let db = connection();
@@ -73,7 +77,9 @@ impl Update<(), DataError> for NewEpisode {
     }
 }
 
-impl Index<(), DataError> for NewEpisode {
+impl Index<()> for NewEpisode {
+    type Error = DataError;
+
     // Does not update the episode description if it's the only thing that has
     // changed.
     fn index(&self) -> Result<(), DataError> {

hammond-data/src/models/new_podcast.rs

@@ -26,8 +26,10 @@ pub(crate) struct NewPodcast {
     source_id: i32,
 }
 
-impl Insert<(), DataError> for NewPodcast {
+impl Insert<()> for NewPodcast {
-    fn insert(&self) -> Result<(), DataError> {
+    type Error = DataError;
+
+    fn insert(&self) -> Result<(), Self::Error> {
         use schema::podcast::dsl::*;
         let db = connection();
         let con = db.get()?;
@@ -40,8 +42,10 @@ impl Insert<(), DataError> for NewPodcast {
     }
 }
 
-impl Update<(), DataError> for NewPodcast {
+impl Update<()> for NewPodcast {
-    fn update(&self, podcast_id: i32) -> Result<(), DataError> {
+    type Error = DataError;
+
+    fn update(&self, podcast_id: i32) -> Result<(), Self::Error> {
         use schema::podcast::dsl::*;
         let db = connection();
         let con = db.get()?;
@@ -57,7 +61,9 @@ impl Update<(), DataError> for NewPodcast {
 
 // TODO: Maybe return an Enum<Action(Resut)> Instead.
 // It would make unti testing better too.
-impl Index<(), DataError> for NewPodcast {
+impl Index<()> for NewPodcast {
+    type Error = DataError;
+
     fn index(&self) -> Result<(), DataError> {
         let exists = dbqueries::podcast_exists(self.source_id)?;
 

hammond-data/src/models/podcast.rs

@@ -25,10 +25,12 @@ pub struct Podcast {
     source_id: i32,
 }
 
-impl Save<Podcast, DataError> for Podcast {
+impl Save<Podcast> for Podcast {
+    type Error = DataError;
+
     /// Helper method to easily save/"sync" current state of self to the
     /// Database.
-    fn save(&self) -> Result<Podcast, DataError> {
+    fn save(&self) -> Result<Podcast, Self::Error> {
         let db = connection();
         let tempdb = db.get()?;
 

hammond-data/src/models/source.rs

@@ -34,10 +34,12 @@ pub struct Source {
     http_etag: Option<String>,
 }
 
-impl Save<Source, DataError> for Source {
+impl Save<Source> for Source {
+    type Error = DataError;
+
     /// Helper method to easily save/"sync" current state of self to the
     /// Database.
-    fn save(&self) -> Result<Source, DataError> {
+    fn save(&self) -> Result<Source, Self::Error> {
         let db = connection();
         let con = db.get()?;