feat: make orm row decoding fallible (#361)

Author: KKould

kite_sql_serde_macros/src/orm.rs

@@ -66,7 +66,9 @@ pub(crate) fn handle(ast: DeriveInput) -> Result<TokenStream, Error> {
         ));
     };
 
-    let mut assignments = Vec::new();
+    let mut field_initializers = Vec::new();
+    let mut field_index_declarations = Vec::new();
+    let mut field_index_resolvers = Vec::new();
     let mut params = Vec::new();
     let mut orm_fields = Vec::new();
     let mut orm_columns = Vec::new();
@@ -132,6 +134,13 @@ pub(crate) fn handle(ast: DeriveInput) -> Result<TokenStream, Error> {
                     "decimal field cannot be skipped",
                 ));
             }
+            generics
+                .make_where_clause()
+                .predicates
+                .push(parse_quote!(#field_ty : ::core::default::Default));
+            field_initializers.push(quote! {
+                #field_name: ::core::default::Default::default()
+            });
             continue;
         }
 
@@ -163,6 +172,7 @@ pub(crate) fn handle(ast: DeriveInput) -> Result<TokenStream, Error> {
         let is_unique = field.unique;
         let is_index = field.index;
         let column_index = orm_columns.len();
+        let field_index_ident = format_ident!("__kite_orm_{field_name}_index");
 
         persisted_columns.push((field_name_string, column_name.clone()));
         column_names.push(column_name.clone());
@@ -223,11 +233,22 @@ pub(crate) fn handle(ast: DeriveInput) -> Result<TokenStream, Error> {
             quote! { None::<::kite_sql::types::value::DataValue> }
         };
 
-        assignments.push(quote! {
-            if let Some(value) = ::kite_sql::orm::try_get::<#field_ty>(&mut tuple, schema, #column_name_lit) {
-                struct_instance.#field_name = value;
+        field_index_declarations.push(quote! {
+            let mut #field_index_ident = None;
+        });
+        field_index_resolvers.push(quote! {
+            if #field_index_ident.is_none() && __kite_orm_column_name == #column_name_lit {
+                #field_index_ident = Some(__kite_orm_index);
+                __kite_orm_found_fields += 1;
             }
         });
+        field_initializers.push(quote! {
+            #field_name: ::kite_sql::orm::take_value_at::<#field_ty>(
+                &mut tuple,
+                #field_index_ident,
+                #column_name_lit,
+            )?
+        });
         params.push(quote! {
             (#placeholder_lit, ::kite_sql::orm::ToDataValue::to_data_value(&self.#field_name))
         });
@@ -379,23 +400,31 @@ pub(crate) fn handle(ast: DeriveInput) -> Result<TokenStream, Error> {
     let primary_key_value = primary_key_value.expect("primary key checked above");
     let _primary_key_column = primary_key_column.expect("primary key checked above");
     let _primary_key_placeholder = primary_key_placeholder.expect("primary key checked above");
-    let mut from_generics = generics.clone();
-    from_generics.params.insert(0, parse_quote!('__kite_arena));
-    from_generics.params.insert(0, parse_quote!('__kite_schema));
-    let (from_impl_generics, _, from_where_clause) = from_generics.split_for_impl();
+    let field_count = field_index_declarations.len();
     let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
 
     Ok(quote! {
-        impl #from_impl_generics ::core::convert::From<(&::kite_sql::types::tuple::SchemaView<'__kite_schema, '__kite_arena>, ::kite_sql::types::tuple::Tuple)>
+        impl #impl_generics ::kite_sql::orm::FromQueryRow
             for #struct_name #ty_generics
-            #from_where_clause
+            #where_clause
         {
-            fn from((schema, mut tuple): (&::kite_sql::types::tuple::SchemaView<'__kite_schema, '__kite_arena>, ::kite_sql::types::tuple::Tuple)) -> Self {
-                let mut struct_instance = <Self as ::core::default::Default>::default();
-
-                #(#assignments)*
+            fn from_query_row(
+                schema: &::kite_sql::types::tuple::SchemaView<'_, '_>,
+                mut tuple: ::kite_sql::types::tuple::Tuple,
+            ) -> ::std::result::Result<Self, ::kite_sql::errors::DatabaseError> {
+                let mut __kite_orm_found_fields = 0usize;
+                #(#field_index_declarations)*
+                for (__kite_orm_index, __kite_orm_column) in schema.iter().enumerate() {
+                    let __kite_orm_column_name = __kite_orm_column.name();
+                    #(#field_index_resolvers)*
+                    if __kite_orm_found_fields == #field_count {
+                        break;
+                    }
+                }
 
-                struct_instance
+                Ok(Self {
+                    #(#field_initializers),*
+                })
             }
         }
 

kite_sql_serde_macros/src/projection.rs

@@ -1,7 +1,7 @@
 use darling::ast::Data;
 use darling::{FromDeriveInput, FromField};
 use proc_macro2::{Span, TokenStream};
-use quote::quote;
+use quote::{format_ident, quote};
 use syn::{parse_quote, DeriveInput, Error, Generics, Ident, LitStr, Type};
 
 #[derive(Debug, FromDeriveInput)]
@@ -34,7 +34,9 @@ pub(crate) fn handle(ast: DeriveInput) -> Result<TokenStream, Error> {
     };
 
     let mut projection_exprs = Vec::new();
-    let mut assignments = Vec::new();
+    let mut field_initializers = Vec::new();
+    let mut field_index_declarations = Vec::new();
+    let mut field_index_resolvers = Vec::new();
 
     for field in data_struct.fields {
         let ProjectionFieldOpts {
@@ -50,6 +52,7 @@ pub(crate) fn handle(ast: DeriveInput) -> Result<TokenStream, Error> {
         let source_name = rename.clone().unwrap_or_else(|| field_name_string.clone());
         let source_name_lit = LitStr::new(&source_name, Span::call_site());
         let field_name_lit = LitStr::new(&field_name_string, Span::call_site());
+        let field_index_ident = format_ident!("__kite_projection_{field_name}_index");
         let relation_expr = if let Some(source_relation) = from {
             let relation_lit = LitStr::new(&source_relation, Span::call_site());
             quote!(#relation_lit)
@@ -74,17 +77,25 @@ pub(crate) fn handle(ast: DeriveInput) -> Result<TokenStream, Error> {
                 scope.column_ref(#relation_expr, #source_name_lit)?
             }
         });
-        assignments.push(quote! {
-            if let Some(value) = ::kite_sql::orm::try_get::<#field_ty>(&mut tuple, schema, #field_name_lit) {
-                struct_instance.#field_name = value;
+        field_index_declarations.push(quote! {
+            let mut #field_index_ident = None;
+        });
+        field_index_resolvers.push(quote! {
+            if #field_index_ident.is_none() && __kite_orm_column_name == #field_name_lit {
+                #field_index_ident = Some(__kite_orm_index);
+                __kite_orm_found_fields += 1;
             }
         });
+        field_initializers.push(quote! {
+            #field_name: ::kite_sql::orm::take_value_at::<#field_ty>(
+                &mut tuple,
+                #field_index_ident,
+                #field_name_lit,
+            )?
+        });
     }
 
-    let mut from_generics = generics.clone();
-    from_generics.params.insert(0, parse_quote!('__kite_arena));
-    from_generics.params.insert(0, parse_quote!('__kite_schema));
-    let (from_impl_generics, _, from_where_clause) = from_generics.split_for_impl();
+    let field_count = field_index_declarations.len();
     let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
 
     Ok(quote! {
@@ -105,13 +116,26 @@ pub(crate) fn handle(ast: DeriveInput) -> Result<TokenStream, Error> {
             }
         }
 
-        impl #from_impl_generics From<(&::kite_sql::types::tuple::SchemaView<'__kite_schema, '__kite_arena>, ::kite_sql::types::tuple::Tuple)> for #struct_name #ty_generics
-        #from_where_clause
+        impl #impl_generics ::kite_sql::orm::FromQueryRow for #struct_name #ty_generics
+        #where_clause
         {
-            fn from((schema, mut tuple): (&::kite_sql::types::tuple::SchemaView<'__kite_schema, '__kite_arena>, ::kite_sql::types::tuple::Tuple)) -> Self {
-                let mut struct_instance = <Self as ::std::default::Default>::default();
-                #(#assignments)*
-                struct_instance
+            fn from_query_row(
+                schema: &::kite_sql::types::tuple::SchemaView<'_, '_>,
+                mut tuple: ::kite_sql::types::tuple::Tuple,
+            ) -> ::std::result::Result<Self, ::kite_sql::errors::DatabaseError> {
+                let mut __kite_orm_found_fields = 0usize;
+                #(#field_index_declarations)*
+                for (__kite_orm_index, __kite_orm_column) in schema.iter().enumerate() {
+                    let __kite_orm_column_name = __kite_orm_column.name();
+                    #(#field_index_resolvers)*
+                    if __kite_orm_found_fields == #field_count {
+                        break;
+                    }
+                }
+
+                Ok(Self {
+                    #(#field_initializers),*
+                })
             }
         }
     })

src/db.rs

@@ -37,6 +37,8 @@ use crate::optimizer::heuristic::batch::HepBatchStrategy;
 use crate::optimizer::heuristic::optimizer::HepOptimizerPipeline;
 use crate::optimizer::rule::implementation::ImplementationRuleImpl;
 use crate::optimizer::rule::normalization::NormalizationRuleImpl;
+#[cfg(feature = "orm")]
+use crate::orm::FromQueryRow;
 use crate::planner::operator::Operator;
 use crate::planner::{LogicalPlan, PlanArena, TableArenaCell};
 #[cfg(all(not(target_arch = "wasm32"), feature = "lmdb"))]
@@ -945,12 +947,12 @@ pub trait ResultIter: BorrowResultIter + Iterator<Item = Result<Tuple, DatabaseE
     /// Converts this iterator into a typed ORM iterator.
     ///
     /// This is available when the `orm` feature is enabled and the target type
-    /// implements `From<(&SchemaView, Tuple)>`, which is typically generated by
-    /// `#[derive(Model)]`.
+    /// implements `FromQueryRow`, which is typically generated by
+    /// `#[derive(Model)]` or `#[derive(Projection)]`.
     fn orm<T>(self) -> OrmIter<Self, T>
     where
         Self: Sized,
-        T: for<'view, 'schema, 'arena> From<(&'view SchemaView<'schema, 'arena>, Tuple)>,
+        T: FromQueryRow,
     {
         OrmIter::new(self)
     }
@@ -969,7 +971,7 @@ pub struct OrmIter<I, T> {
 impl<I, T> OrmIter<I, T>
 where
     I: ResultIter,
-    T: for<'view, 'schema, 'arena> From<(&'view SchemaView<'schema, 'arena>, Tuple)>,
+    T: FromQueryRow,
 {
     fn new(inner: I) -> Self {
         Self {
@@ -993,7 +995,7 @@ where
 impl<I, T> Iterator for OrmIter<I, T>
 where
     I: ResultIter,
-    T: for<'view, 'schema, 'arena> From<(&'view SchemaView<'schema, 'arena>, Tuple)>,
+    T: FromQueryRow,
 {
     type Item = Result<T, DatabaseError>;
 
@@ -1002,7 +1004,7 @@ where
             Ok(tuple) => tuple,
             Err(err) => return Some(Err(err)),
         };
-        Some(Ok(self.inner.schema(|schema| T::from((schema, tuple)))))
+        Some(self.inner.schema(|schema| T::from_query_row(schema, tuple)))
     }
 }