制造业成本管理系统搭建案例：从车间成本模糊到单品成本精准核算实操

// 产品成本计算服务
public class ProductCostCalculator
{
    private readonly ICostRepository _costRepository;
    
    public ProductCostCalculator(ICostRepository costRepository)
    {
        _costRepository = costRepository;
    }
    
    /// 

    /// 计算单品成本
    /// 
    /// 产品ID
    /// 批次号
    /// 成本明细
    public async Task CalculateProductCostAsync(int productId, string batchNumber)
    {
        // 获取直接材料成本
        var materialCost = await _costRepository.GetMaterialCostAsync(productId, batchNumber);
        
        // 获取直接人工成本
        var laborCost = await _costRepository.GetLaborCostAsync(productId, batchNumber);
        
        // 计算制造费用分摊
        var overheadCost = await CalculateOverheadCostAsync(productId, batchNumber);
        
        // 汇总成本
        var totalCost = materialCost + laborCost + overheadCost;
        
        return new ProductCostDetail
        {
            ProductId = productId,
            BatchNumber = batchNumber,
            MaterialCost = materialCost,
            LaborCost = laborCost,
            OverheadCost = overheadCost,
            TotalCost = totalCost,
            CalculationTime = DateTime.Now
        };
    }
    
    /// 

    /// 计算制造费用分摊
    /// 
    private async Task CalculateOverheadCostAsync(int productId, string batchNumber)
    {
        // 基于作业成本法(ABC)的费用分摊算法
        var overheadActivities = await _costRepository.GetOverheadActivitiesAsync();
        decimal totalOverheadCost = 0;
        
        foreach (var activity in overheadActivities)
        {
            // 获取成本动因量
            var driverQuantity = await _costRepository.GetCostDriverQuantityAsync(
                productId, batchNumber, activity.CostDriverId);
            
            // 计算分摊金额
            var allocatedCost = activity.Rate * driverQuantity;
            totalOverheadCost += allocatedCost;
        }
        
        return totalOverheadCost;
    }
}

// 产品成本实体
public class ProductCost
{
    public int Id { get; set; }
    
    [Required]
    public int ProductId { get; set; }
    
    [Required]
    [MaxLength(50)]
    public string BatchNumber { get; set; }
    
    [Precision(18, 4)]
    public decimal MaterialCost { get; set; }
    
    [Precision(18, 4)]
    public decimal LaborCost { get; set; }
    
    [Precision(18, 4)]
    public decimal OverheadCost { get; set; }
    
    [Precision(18, 4)]
    public decimal TotalCost { get; set; }
    
    public DateTime CalculationTime { get; set; }
    
    // 导航属性
    public virtual Product Product { get; set; }
    public virtual ICollection CostDetails { get; set; }
}

// 成本明细实体
public class CostDetail
{
    public int Id { get; set; }
    
    public int ProductCostId { get; set; }
    
    [Required]
    [MaxLength(100)]
    public string CostType { get; set; } // 成本类型：材料、人工、制造费用
    
    [Required]
    [MaxLength(200)]
    public string Description { get; set; }
    
    [Precision(18, 4)]
    public decimal Amount { get; set; }
    
    // 导航属性
    public virtual ProductCost ProductCost { get; set; }
}

// 数据库上下文
public class CostManagementContext : DbContext
{
    public CostManagementContext(DbContextOptions options) 
        : base(options)
    {
    }
    
    public DbSet ProductCosts { get; set; }
    public DbSet CostDetails { get; set; }
    
    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        // 配置实体关系和数据约束
        modelBuilder.Entity()
            .HasMany(pc => pc.CostDetails)
            .WithOne(cd => cd.ProductCost)
            .HasForeignKey(cd => cd.ProductCostId);
    }
}