DieselCrud traits and derives

crates/diesel_crud_derive/src/read.rs

@@ -0,0 +1,38 @@
+use proc_macro2::Ident;
+use quote::quote;
+use syn::Expr;
+
+use crate::{common, StructAttributes};
+
+pub(crate) fn derive_diesel_crud_read_impl(
+    StructAttributes {
+        table, entity, pk, ..
+    }: &StructAttributes,
+    identifier: &Ident,
+) -> proc_macro2::TokenStream {
+    let body = function_body(table);
+    let return_type = common::return_type(quote! { Self::Entity });
+
+    quote! {
+        #[automatically_derived]
+        impl lib::diesel_crud_trait::DieselCrudRead for #identifier {
+            type PK = #pk;
+            type Entity = #entity;
+            fn read<'a, 'b>(&'a self, pk: Self::PK) -> #return_type
+                where
+                    Self: Sync + 'a,
+                    'a: 'b
+            {
+                Box::pin(async move {
+                    #body
+                })
+            }
+        }
+    }
+}
+
+fn function_body(table: &Expr) -> proc_macro2::TokenStream {
+    common::function_body(quote! {
+        diesel_async::RunQueryDsl::get_result(diesel::QueryDsl::find(#table::table::table(), pk), &mut connection).await.map_err(Into::into)
+    })
+}