first version

app/Models/ProductPriceModel.php

@@ -0,0 +1,54 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Factories\HasFactory;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+
+/**
+ * 商品价格模型（同一商品按客户等级定价，联合键 product_id + level_id）
+ */
+class ProductPriceModel extends Model
+{
+    use HasFactory;
+
+    protected $table = 'product_price';
+    protected $primaryKey = 'id';
+
+    protected $fillable = [
+        'product_id',
+        'level_id',
+        'price',
+    ];
+
+    protected $casts = [
+        'product_id' => 'integer',
+        'level_id' => 'integer',
+        'price' => 'decimal:2',
+    ];
+
+    /**
+     * 所属商品
+     */
+    public function product(): BelongsTo
+    {
+        return $this->belongsTo(ProductModel::class, 'product_id', 'id');
+    }
+
+    /**
+     * 所属客户等级
+     */
+    public function level(): BelongsTo
+    {
+        return $this->belongsTo(CustomerLevelModel::class, 'level_id', 'id');
+    }
+
+    /**
+     * 按商品 + 等级筛选价格
+     */
+    public function scopeForProductLevel($query, int $productId, int $levelId)
+    {
+        return $query->where('product_id', $productId)->where('level_id', $levelId);
+    }
+}