add sync function

macros/src/lib.rs

@@ -4,8 +4,6 @@ use syn::{parse_macro_input, Data, DeriveInput, Fields};
 
 // TODO: wrap functions in a trait
 
-// TODO: add sync function (set fields of self by querying db)
-
 // TODO: doc comments
 
 #[proc_macro_derive(Table)]
@@ -126,7 +124,7 @@ pub fn derive_table(input: TokenStream) -> TokenStream {
     );
 
     let update_fn = quote! {
-        pub fn update(&mut self, conn: &rusqlite::Connection) -> rusqlite::Result<bool>
+        pub fn update(&self, conn: &rusqlite::Connection) -> rusqlite::Result<bool>
             where #(#to_sql_trait_bounds),*
         {
             if self.id.is_none() {
@@ -138,6 +136,22 @@ pub fn derive_table(input: TokenStream) -> TokenStream {
     };
 
 
+    let sync_fn = quote! {
+        pub fn sync(&mut self, conn: &rusqlite::Connection) -> rusqlite::Result<bool>
+            where #(#from_sql_trait_bounds),*
+        {
+            if self.id.is_none() {
+                return Ok(false);
+            }
+            match #struct_name::get_by_id(conn, self.id.unwrap())? {
+                Some(person) => *self = person,
+                _ => return Ok(false),
+            };
+            Ok(true)
+        }
+    };
+
+
     let get_by_id_fn = quote! {
         pub fn get_by_id(conn: &rusqlite::Connection, id: i64) -> rusqlite::Result<Option<Self>>
         where
@@ -197,6 +211,7 @@ pub fn derive_table(input: TokenStream) -> TokenStream {
             #insert_fn
             #upsert_fn
             #update_fn
+            #sync_fn
             #get_by_id_fn
             #delete_fn
             #delete_by_id_fn

src/test/macros.rs

@@ -87,11 +87,22 @@ fn test_table_derive_macro() {
     let larry_copy = Person::get_by_id(&conn, larry_id).expect("Querying a row should work");
     assert_eq!(larry_copy, Some(larry.clone()), "Retrieving upserted row should give an identical row");
 
+    conn.execute("UPDATE Person SET (age) = (27) WHERE id = ?1", [larry_id])
+        .expect("Explicit Sqlite statement (not a library test) failed");
+
+    let found = larry.sync(&conn).expect("Syncing struct to existing row should succeed");
+    assert!(found, "Row should have been found");
+    assert_eq!(larry.age, 27, "Syncing struct to edited table row should work");
+
     Person::drop_table(&conn).expect("Dropping table should work");
     Person::drop_table(&conn).expect_err("Dropping previously dropped table should err");
+
+    let exists: bool = conn.query_row("SELECT EXISTS(SELECT 1 FROM sqlite_master WHERE type='table' AND name='Person');", [], |row| row.get(0)).expect("Explicit Sqlite statement (not a library test) failed");
+    assert!(!exists, "Deleted table should not exist anymore but does");
 }
 
 
+
 // TODO: implement compile-error test(s) -- perhaps with `trybuild`?
 //
 // #[test]