apksel-dev/apskel-pos-backend
4
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

feat(order): support weight-based products

Browse Source 
Products like fish are sold per weighing (4.2 ons, 5.6 ons), which the
order line could not represent: quantity is INTEGER and prices are always
computed as quantity * unit_price.

Model one weighing as one order line. quantity stays INTEGER and keeps
meaning "how many items"; the measured amount goes into a new nullable
order_items.weight, and the line is priced weight * unit_price. Two
weighings of the same product are two lines, never merged into one.

Keeping quantity integral avoids float comparisons in void, refund and
split bill, where accumulated rounding error would silently misbehave —
"1.4 + 1.4 + 1.4" is not 4.2 in float64, which would leave a fully paid
split-bill item marked unpaid.

BillableQuantity() is now the single place that decides between weight
and count; every price and cost calculation goes through it. Missing one
would bill a 4.2 ons fish as a single ons — wrong money, no error.

Two database constraints back the design: a weighed line always carries a
positive weight, and its quantity is pinned to 1. The latter also makes
void all-or-nothing for weighed lines, so the row-splitting branch can
never produce a zero-weight remainder row.

Also wires product.unit_id through the API, which was previously not
settable at all, and corrects the misleading comment on the request's
unit_price field — that value has never been used; price always comes
from the database.

Design notes and the audit of every price multiplication site are in
docs/rfc-weight-based-products.md.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
This commit is contained in:
efrilm
2026-09-06 17:14:42 +07:00
co-authored by Claude Opus 5
parent 1e5573af75
commit 992bb04816
30 changed files with 901 additions and 66 deletions
Download Patch File Download Diff File Expand all files Collapse all files
internal/contract/analytics_contract.go
+2
View File
@@ -198,6 +198,7 @@ type ProductAnalyticsData struct {
CategoryName string `json:"category_name"`
CategoryOrder int `json:"category_order"`
QuantitySold int64 `json:"quantity_sold"`
WeightSold float64 `json:"weight_sold"`
Revenue float64 `json:"revenue"`
AveragePrice float64 `json:"average_price"`
OrderCount int64 `json:"order_count"`
@@ -324,6 +325,7 @@ type ParentCategoryAnalyticsProductData struct {
ProductSku string `json:"product_sku"`
ProductPrice float64 `json:"product_price"`
QuantitySold int64 `json:"quantity_sold"`
WeightSold float64 `json:"weight_sold"`
Revenue float64 `json:"revenue"`
AveragePrice float64 `json:"average_price"`
OrderCount int64 `json:"order_count"`
internal/contract/order_contract.go
+35 -27
View File
@@ -40,13 +40,16 @@ type UpdateOrderRequest struct {
}
type CreateOrderItemRequest struct {
ProductID uuid.UUID `json:"product_id" validate:"required"`
ProductVariantID *uuid.UUID `json:"product_variant_id,omitempty"`
Quantity int `json:"quantity" validate:"required,min=1"`
UnitPrice *float64 `json:"unit_price,omitempty" validate:"omitempty,min=0"` // Optional, will use database price if not provided
Modifiers []map[string]interface{} `json:"modifiers,omitempty"`
Notes *string `json:"notes,omitempty" validate:"omitempty,max=500"`
Metadata map[string]interface{} `json:"metadata,omitempty"`
ProductID uuid.UUID `json:"product_id" validate:"required"`
ProductVariantID *uuid.UUID `json:"product_variant_id,omitempty"`
Quantity int `json:"quantity" validate:"required,min=1"`
// Weight is required for products with sell_by = "weight" and must be absent otherwise.
// One weighing is one line, so quantity stays 1 and the line is priced weight * unit_price.
Weight *float64 `json:"weight,omitempty" validate:"omitempty,gt=0"`
UnitPrice *float64 `json:"unit_price,omitempty" validate:"omitempty,min=0"` // Ignored: price always comes from the database
Modifiers []map[string]interface{} `json:"modifiers,omitempty"`
Notes *string `json:"notes,omitempty" validate:"omitempty,max=500"`
Metadata map[string]interface{} `json:"metadata,omitempty"`
}
type UpdateOrderItemRequest struct {
@@ -92,26 +95,31 @@ type OrderResponse struct {
}
type OrderItemResponse struct {
ID uuid.UUID `json:"id"`
OrderID uuid.UUID `json:"order_id"`
ProductID uuid.UUID `json:"product_id"`
ProductName string `json:"product_name"`
ProductVariantID *uuid.UUID `json:"product_variant_id"`
ProductVariantName *string `json:"product_variant_name,omitempty"`
CategoryID *uuid.UUID `json:"category_id,omitempty"`
CategoryName *string `json:"category_name,omitempty"`
Quantity int `json:"quantity"`
UnitPrice float64 `json:"unit_price"`
TotalPrice float64 `json:"total_price"`
Modifiers []map[string]interface{} `json:"modifiers"`
Notes *string `json:"notes,omitempty"`
Metadata map[string]interface{} `json:"metadata,omitempty"`
Status string `json:"status"`
CreatedAt time.Time `json:"created_at"`
UpdatedAt time.Time `json:"updated_at"`
PrinterType string `json:"printer_type"`
PrintToChecker bool `json:"print_to_checker"`
PaidQuantity int `json:"paid_quantity"`
ID uuid.UUID `json:"id"`
OrderID uuid.UUID `json:"order_id"`
ProductID uuid.UUID `json:"product_id"`
ProductName string `json:"product_name"`
ProductVariantID *uuid.UUID `json:"product_variant_id"`
ProductVariantName *string `json:"product_variant_name,omitempty"`
CategoryID *uuid.UUID `json:"category_id,omitempty"`
CategoryName *string `json:"category_name,omitempty"`
Quantity int `json:"quantity"`
// Weight is set only for products sold by weight; the line is priced weight * unit_price.
Weight *float64 `json:"weight,omitempty"`
UnitID *uuid.UUID `json:"unit_id,omitempty"`
UnitName *string `json:"unit_name,omitempty"`
UnitAbbreviation *string `json:"unit_abbreviation,omitempty"`
UnitPrice float64 `json:"unit_price"`
TotalPrice float64 `json:"total_price"`
Modifiers []map[string]interface{} `json:"modifiers"`
Notes *string `json:"notes,omitempty"`
Metadata map[string]interface{} `json:"metadata,omitempty"`
Status string `json:"status"`
CreatedAt time.Time `json:"created_at"`
UpdatedAt time.Time `json:"updated_at"`
PrinterType string `json:"printer_type"`
PrintToChecker bool `json:"print_to_checker"`
PaidQuantity int `json:"paid_quantity"`
}
type ListOrdersQuery struct {
internal/contract/product_contract.go
+6
View File
@@ -18,6 +18,8 @@ type CreateProductRequest struct {
ImageURL *string `json:"image_url,omitempty" validate:"omitempty,max=500"`
PrinterType *string `json:"printer_type,omitempty" validate:"omitempty,max=50"`
PrintToChecker *bool `json:"print_to_checker,omitempty"`
UnitID *uuid.UUID `json:"unit_id,omitempty"`
SellBy *string `json:"sell_by,omitempty" validate:"omitempty,oneof=unit weight"`
Metadata map[string]interface{} `json:"metadata,omitempty"`
IsActive *bool `json:"is_active,omitempty"`
Variants []CreateProductVariantRequest `json:"variants,omitempty"`
@@ -38,6 +40,8 @@ type UpdateProductRequest struct {
ImageURL *string `json:"image_url,omitempty" validate:"omitempty,max=500"`
PrinterType *string `json:"printer_type,omitempty" validate:"omitempty,max=50"`
PrintToChecker *bool `json:"print_to_checker,omitempty"`
UnitID *uuid.UUID `json:"unit_id,omitempty"`
SellBy *string `json:"sell_by,omitempty" validate:"omitempty,oneof=unit weight"`
Metadata map[string]interface{} `json:"metadata,omitempty"`
IsActive *bool `json:"is_active,omitempty"`
ReorderLevel *int `json:"reorder_level,omitempty" validate:"omitempty,min=0"`
@@ -73,6 +77,8 @@ type ProductResponse struct {
BusinessType string `json:"business_type"`
ImageURL *string `json:"image_url"`
PrinterType string `json:"printer_type"`
UnitID *uuid.UUID `json:"unit_id,omitempty"`
SellBy string `json:"sell_by"`
PrintToChecker bool `json:"print_to_checker"`
Metadata map[string]interface{} `json:"metadata"`
IsActive bool `json:"is_active"`
internal/contract/self_order_contract.go
+1
View File
@@ -58,6 +58,7 @@ type SelfOrderCreateOrderItem struct {
ProductID uuid.UUID `json:"product_id" validate:"required"`
ProductVariantID *uuid.UUID `json:"product_variant_id,omitempty"`
Quantity int `json:"quantity" validate:"required,min=1"`
Weight *float64 `json:"weight,omitempty" validate:"omitempty,gt=0"`
Notes *string `json:"notes,omitempty"`
}