From 7e53eea27a6b7d23edb4e00102d33a909e2ab2eb Mon Sep 17 00:00:00 2001
From: Jack Zhuang <277994282+os-zhuang@users.noreply.github.com>
Date: Sun, 7 Jun 2026 15:41:26 +0800
Subject: [PATCH] feat(showcase): make invoice line amount a computed
 (expression) currency
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Give showcase_invoice_line.amount an `expression` (quantity × unit_price). It
stays a stored currency column — the server only treats `type: 'formula'` as
computed, so the client-sent value is persisted and the parent Invoice.total
summary still rolls it up — but the new line-item grid reads the expression to
render Amount read-only and recompute it live as quantity/unit_price change.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---
 .../app-showcase/src/objects/invoice.object.ts     | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/examples/app-showcase/src/objects/invoice.object.ts b/examples/app-showcase/src/objects/invoice.object.ts
index 0e4746850..93c1d35e1 100644
--- a/examples/app-showcase/src/objects/invoice.object.ts
+++ b/examples/app-showcase/src/objects/invoice.object.ts
@@ -61,6 +61,18 @@ export const InvoiceLine = ObjectSchema.create({
     product: Field.text({ label: 'Product', required: true, maxLength: 200 }),
     quantity: Field.number({ label: 'Qty', required: true, min: 0, defaultValue: 1 }),
     unit_price: Field.currency({ label: 'Unit Price', scale: 2, min: 0 }),
-    amount: Field.currency({ label: 'Amount', scale: 2, min: 0 }),
+    // Amount = Qty × Unit Price. Kept as a *stored* currency column (so the
+    // parent Invoice.total summary can roll it up — summary aggregation reads
+    // stored columns, not on-read formula fields), but the `expression` makes
+    // the line-item grid render it READ-ONLY and recompute it live client-side
+    // as quantity/unit_price change, then persist the computed value. The
+    // server does not treat a non-`formula` field's expression as computed, so
+    // the client-sent value is stored as-is.
+    amount: Field.currency({
+      label: 'Amount',
+      scale: 2,
+      min: 0,
+      expression: 'record.quantity * record.unit_price',
+    }),
   },
 });