paginate books

calibre-db/src/calibre.rs

@@ -24,7 +24,7 @@ impl Calibre {
         &self,
         limit: u64,
         cursor: Option<&str>,
-        sort_order: SortOrder,
+        sort_order: &SortOrder,
     ) -> Result<Vec<Book>, DataStoreError> {
         let conn = self.pool.get()?;
         Book::multiple(&conn, limit, cursor, sort_order)
@@ -91,6 +91,16 @@ impl Calibre {
         Author::has_more_authors(&conn, author_sort)
     }
 
+    pub fn has_previous_books(&self, book_sort: &str) -> Result<bool, DataStoreError> {
+        let conn = self.pool.get()?;
+        Book::has_previous_books(&conn, book_sort)
+    }
+
+    pub fn has_more_books(&self, book_sort: &str) -> Result<bool, DataStoreError> {
+        let conn = self.pool.get()?;
+        Book::has_more_books(&conn, book_sort)
+    }
+
     pub fn scalar_author(&self, id: u64) -> Result<Author, DataStoreError> {
         let conn = self.pool.get()?;
         Author::scalar_author(&conn, id)
@@ -108,7 +118,7 @@ mod tests {
     #[test]
     fn books() {
         let c = init_calibre();
-        let books = c.books(10, None, SortOrder::ASC).unwrap();
+        let books = c.books(10, None, &SortOrder::ASC).unwrap();
         assert_eq!(books.len(), 4);
     }
 

calibre-db/src/data/book.rs

@@ -28,9 +28,9 @@ impl Book {
         conn: &Connection,
         limit: u64,
         cursor: Option<&str>,
-        sort_order: SortOrder,
+        sort_order: &SortOrder,
     ) -> Result<Vec<Self>, DataStoreError> {
-        let pagination = Pagination::new("sort", cursor, limit, sort_order);
+        let pagination = Pagination::new("sort", cursor, limit, *sort_order);
         pagination.paginate(
             conn,
             "SELECT id, title, sort, path FROM books",
@@ -71,4 +71,22 @@ impl Book {
         let params = named_params! { ":id": id };
         Ok(stmt.query_row(params, Self::from_row)?)
     }
+
+    pub fn has_previous_books(conn: &Connection, sort_title: &str) -> Result<bool, DataStoreError> {
+        let mut stmt = conn
+            .prepare("SELECT Count(1) FROM books WHERE sort < (:sort_title) ORDER BY sort DESC")?;
+        let params = named_params! { ":sort_title": sort_title};
+        let count: u64 = stmt.query_row(params, |x| x.get(0))?;
+
+        Ok(count > 0)
+    }
+
+    pub fn has_more_books(conn: &Connection, sort_title: &str) -> Result<bool, DataStoreError> {
+        let mut stmt = conn
+            .prepare("SELECT Count(1) FROM books WHERE sort > (:sort_title) ORDER BY sort ASC")?;
+        let params = named_params! { ":sort_title": sort_title};
+        let count: u64 = stmt.query_row(params, |x| x.get(0))?;
+
+        Ok(count > 0)
+    }
 }