0 is out of stock and nothing is available from now on

migration/src/lib.rs

@@ -41,6 +41,7 @@ mod m20260621_000003_discount_profiles;
 mod m20260621_000004_add_business_sale_price_to_products;
 mod m20260622_000001_audience_discount_profiles;
 mod m20260622_000002_product_variants;
+mod m20260622_000003_variant_stock_nullable;
 pub struct Migrator;
 
 #[async_trait::async_trait]
@@ -86,6 +87,7 @@ impl MigratorTrait for Migrator {
             Box::new(m20260621_000004_add_business_sale_price_to_products::Migration),
             Box::new(m20260622_000001_audience_discount_profiles::Migration),
             Box::new(m20260622_000002_product_variants::Migration),
+            Box::new(m20260622_000003_variant_stock_nullable::Migration),
             // inject-above (do not remove this comment)
         ]
     }

migration/src/m20260622_000003_variant_stock_nullable.rs

@@ -0,0 +1,36 @@
+//! Make `product_variants.stock` nullable: a NULL stock means the variant is
+//! "available" but not inventory-tracked — always purchasable, no quantity cap,
+//! and never decremented on order. A numeric stock is tracked/capped as before.
+
+use sea_orm_migration::prelude::*;
+
+#[derive(DeriveMigrationName)]
+pub struct Migration;
+
+#[async_trait::async_trait]
+impl MigrationTrait for Migration {
+    async fn up(&self, m: &SchemaManager) -> Result<(), DbErr> {
+        m.get_connection()
+            .execute_unprepared(
+                r#"
+                ALTER TABLE product_variants ALTER COLUMN stock DROP DEFAULT;
+                ALTER TABLE product_variants ALTER COLUMN stock DROP NOT NULL;
+                "#,
+            )
+            .await?;
+        Ok(())
+    }
+
+    async fn down(&self, m: &SchemaManager) -> Result<(), DbErr> {
+        m.get_connection()
+            .execute_unprepared(
+                r#"
+                UPDATE product_variants SET stock = 0 WHERE stock IS NULL;
+                ALTER TABLE product_variants ALTER COLUMN stock SET DEFAULT 0;
+                ALTER TABLE product_variants ALTER COLUMN stock SET NOT NULL;
+                "#,
+            )
+            .await?;
+        Ok(())
+    }
+}