diff --git a/crates/generator-macros/src/select_include/definitions.rs b/crates/generator-macros/src/select_include/definitions.rs
index 65421d83..5eabeaf7 100644
--- a/crates/generator-macros/src/select_include/definitions.rs
+++ b/crates/generator-macros/src/select_include/definitions.rs
@@ -1,5 +1,5 @@
 use convert_case::Casing;
-use prisma_client_rust_generator_shared::Arity;
+use prisma_client_rust_generator_shared::{Arity, RelationArity};
 use proc_macro2::TokenStream;
 use quote::quote;
 use syn::Field;
@@ -59,15 +59,10 @@ pub fn definitions(input: &Input) -> TokenStream {
                 return None;
             }
 
-            let field = quote! {
-                #(#attrs)*
-                pub #ident: #dollar::#model_path::#ty
-            };
-
-            let field_module = field_in_selectables
+            let (field_type, field_module) = field_in_selectables
                 .zip(field_in_selection.and_then(|f| f.sub_selection.as_ref()))
                 .and_then(|(field_in_selectables, (variant, sub_selection))| {
-                    let Arity::Relation(relation_model_path, _) = &field_in_selectables.arity else {
+                    let Arity::Relation(relation_model_path, arity) = &field_in_selectables.arity else {
 						return None;
 					};
 
@@ -79,8 +74,22 @@ pub fn definitions(input: &Input) -> TokenStream {
                         }
                     };
 
-                    Some(value)
-                });
+                    let base = quote!(#ident::Data);
+
+                    let typ = match arity {
+                    RelationArity::One => base,
+                    RelationArity::Many => quote!(Vec<#base>),
+                    RelationArity::Optional => quote!(Option<#base>),
+                    };
+
+                    Some((typ, Some(value)))
+                })
+                .unwrap_or_else(|| (quote!(#dollar::#model_path::#ty), None));
+
+            let field = quote! {
+                #(#attrs)*
+                pub #ident: #field_type
+            };
 
             Some((field, field_module))
         })
diff --git a/crates/generator-macros/src/select_include/selection/mod.rs b/crates/generator-macros/src/select_include/selection/mod.rs
index 1e671c40..145aecc7 100644
--- a/crates/generator-macros/src/select_include/selection/mod.rs
+++ b/crates/generator-macros/src/select_include/selection/mod.rs
@@ -82,18 +82,6 @@ pub fn selection_to_params(input: &Input, variant: Variant) -> Vec<TokenStream>
                     },
                     Arity::Relation(relation_model_path, relation_arity) => {
                         match (relation_arity, sub_selection) {
-                            (RelationArity::One, None) => quote! {
-                                #into(#variant_type_path::Fetch)
-                            },
-                            (RelationArity::One, Some((selection_variant, selection))) => quote! {
-                                #into(
-                                    #variant_type_path::#selection_variant(
-                                        #dollar::#relation_model_path::#selection_variant! {
-                                            selection_to_params @ #selection
-                                        }.into_iter().collect()
-                                    )
-                                )
-                            },
                             (RelationArity::Many, None) => quote! {
                                 #into(
                                     #variant_type_path::Fetch(
@@ -115,6 +103,21 @@ pub fn selection_to_params(input: &Input, variant: Variant) -> Vec<TokenStream>
                                     )
                                 )
                             },
+                            (RelationArity::One | RelationArity::Optional, None) => quote! {
+                                #into(#variant_type_path::Fetch)
+                            },
+                            (
+                                RelationArity::One | RelationArity::Optional,
+                                Some((selection_variant, selection)),
+                            ) => quote! {
+                                #into(
+                                    #variant_type_path::#selection_variant(
+                                        #dollar::#relation_model_path::#selection_variant! {
+                                            selection_to_params @ #selection
+                                        }.into_iter().collect()
+                                    )
+                                )
+                            },
                         }
                     }
                 }
diff --git a/crates/generator-shared/src/lib.rs b/crates/generator-shared/src/lib.rs
index d8a527da..714349b5 100644
--- a/crates/generator-shared/src/lib.rs
+++ b/crates/generator-shared/src/lib.rs
@@ -19,6 +19,7 @@ pub mod select_include;
 pub enum RelationArity {
     One,
     Many,
+    Optional,
 }
 
 impl Parse for RelationArity {
@@ -28,7 +29,13 @@ impl Parse for RelationArity {
         Ok(match ident.to_string().as_str() {
             "One" => Self::One,
             "Many" => Self::Many,
-            _ => return Err(syn::Error::new_spanned(ident, "expected `One` or `Many`")),
+            "Optional" => Self::Optional,
+            _ => {
+                return Err(syn::Error::new_spanned(
+                    ident,
+                    "expected `One`, `Many`, or `Optional`",
+                ))
+            }
         })
     }
 }
@@ -38,6 +45,7 @@ impl ToTokens for RelationArity {
         tokens.extend(match self {
             Self::One => quote!(One),
             Self::Many => quote!(Many),
+            Self::Optional => quote!(Optional),
         })
     }
 }
@@ -99,7 +107,8 @@ impl FieldTuple {
 
                 let relation_arity = match &field.ast_field().arity {
                     FieldArity::List => RelationArity::Many,
-                    _ => RelationArity::One,
+                    FieldArity::Optional => RelationArity::Optional,
+                    FieldArity::Required => RelationArity::One,
                 };
 
                 Arity::Relation(
diff --git a/integration-tests/tests/lib.rs b/integration-tests/tests/lib.rs
index 0040ea9e..31b49cbf 100644
--- a/integration-tests/tests/lib.rs
+++ b/integration-tests/tests/lib.rs
@@ -8,7 +8,7 @@ mod utils;
 
 #[tokio::test]
 async fn aaaa_run_migrations() -> TestResult {
-    let client = db::new_client().await.unwrap();
+    let client = db::PrismaClient::_builder().build().await.unwrap();
 
     client._db_push().accept_data_loss().await.unwrap();