From 41d2d919ac27e4f9148d84855c1e591c0b100a11 Mon Sep 17 00:00:00 2001
From: Melody Horn <melody@boringcactus.com>
Date: Wed, 30 Jun 2021 00:46:18 -0600
Subject: add Model::new

---
 tosin-macros/src/lib.rs | 39 +++++++++++++++++++++++++++++++++------
 1 file changed, 33 insertions(+), 6 deletions(-)

diff --git a/tosin-macros/src/lib.rs b/tosin-macros/src/lib.rs
index 0da725e..60803ae 100644
--- a/tosin-macros/src/lib.rs
+++ b/tosin-macros/src/lib.rs
@@ -124,6 +124,15 @@ fn to_field_spec(field: &syn::Field) -> FieldInfo<impl quote::ToTokens> {
     }
 }
 
+fn is_id(field: &syn::Field) -> bool {
+    let name_matches = field
+        .ident
+        .as_ref()
+        .map_or(false, |name| name.to_string() == "id");
+    let type_matches = field.ty == syn::parse_str("Option<Id>").unwrap();
+    name_matches && type_matches
+}
+
 fn impl_model(ast: &syn::DeriveInput) -> TokenStream {
     let name = &ast.ident;
     let lowercase_name = quote::format_ident!("{}", name.to_string().to_lowercase());
@@ -136,18 +145,29 @@ fn impl_model(ast: &syn::DeriveInput) -> TokenStream {
         .fields
         .iter()
         .map(|field| {
-            if field
-                .ident
-                .as_ref()
-                .map_or(false, |name| name.to_string() == "id")
-                && field.ty == syn::parse_str("Option<Id>").unwrap()
-            {
+            if is_id(field) {
                 syn::parse_str("Id").unwrap()
             } else {
                 field.ty.clone()
             }
         })
         .collect();
+    let new_params: Vec<_> = ast_data
+        .fields
+        .iter()
+        .filter(|field| !is_id(field))
+        .map(|field| {
+            let ty = &field.ty;
+            let name = &field.ident;
+            quote! { #name: #ty }
+        })
+        .collect();
+    let field_names: Vec<_> = ast_data
+        .fields
+        .iter()
+        .filter(|field| !is_id(field))
+        .map(|field| &field.ident)
+        .collect();
     let FieldsInfo {
         tosin_fields,
         diesel_columns,
@@ -159,6 +179,13 @@ fn impl_model(ast: &syn::DeriveInput) -> TokenStream {
                 name: stringify!(#name),
                 fields: &[ #(#tosin_fields),* ],
             };
+
+            pub fn new(#(#new_params),*) -> Self {
+                Self {
+                    id: None,
+                    #(#field_names),*
+                }
+            }
         }
 
         impl<__DB: tosin::db::diesel_backend::Backend, __ST> tosin::db::Queryable<__ST, __DB> for #name
-- 
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