ASP.NET Web API如何仅查询并更新AdditionalDetailAbstract模型数据？

针对你的场景，核心是避免查询时加载不必要的FullDetails关联数据，同时高效更新AmountPaid字段，以下是几种实用方案：

1. 投影查询+跟踪更新（需先读取数据场景） #

通过Select投影只获取AdditionalDetailAbstract包含的字段，EF不会加载关联的FullDetails，之后将投影对象附加到上下文并标记需要更新的字段：

// 投影到抽象类实例，仅获取需要的字段
var additionalData = dbContext.AdditionalDetail
    .Where(c => c.AdditionalDetailId == 525 && c.CompanyId == 15)
    .Select(c => new AdditionalDetailAbstract
    {
        AdditionalDetailId = c.AdditionalDetailId,
        DetailsId = c.DetailsId,
        CompanyId = c.CompanyId,
        AmountToBePay = c.AmountToBePay,
        AmountPaid = c.AmountPaid
    })
    .FirstOrDefault();

if (additionalData != null)
{
    // 修改AmountPaid字段
    additionalData.AmountPaid = 100.00m; // 替换为实际金额
    
    // 将实体附加到上下文并标记修改
    dbContext.Attach(additionalData);
    dbContext.Entry(additionalData).Property(x => x.AmountPaid).IsModified = true;
    
    dbContext.SaveChanges();
}

2. 直接执行更新操作（性能最优，无需查询实体） #

如果不需要先读取当前数据，直接用EF的批量更新功能（EF Core 7+支持）或原生SQL，完全跳过实体加载步骤，适合大数据量场景：

EF Core 7+ 写法 #

dbContext.AdditionalDetail
    .Where(c => c.AdditionalDetailId == 525 && c.CompanyId == 15)
    .ExecuteUpdate(setters => setters
        .SetProperty(c => c.AmountPaid, 100.00m)); // 替换为实际金额

旧版本EF 原生SQL写法 #

dbContext.Database.ExecuteSqlRaw(
    "UPDATE AdditionalDetail SET AmountPaid = @amountPaid WHERE AdditionalDetailId = @id AND CompanyId = @companyId",
    new SqlParameter("@amountPaid", 100.00m),
    new SqlParameter("@id", 525),
    new SqlParameter("@companyId", 15));

3. 关闭延迟加载（全局/局部避免关联数据加载） #

如果希望默认不加载关联数据，可以全局关闭延迟加载代理，或在局部查询时禁用：

全局关闭（DbContext配置） #

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
    optionsBuilder.UseSqlServer("你的连接字符串")
        .UseLazyLoadingProxies(false); // 关闭延迟加载
}

局部查询禁用 #

var additionalData = dbContext.AdditionalDetail
    .AsNoTracking() // 无需跟踪的话用这个，需要跟踪就去掉
    .Where(c => c.AdditionalDetailId == 525 && c.CompanyId == 15)
    .FirstOrDefault();

// 修改并保存
if (additionalData != null)
{
    additionalData.AmountPaid = 100.00m;
    dbContext.Entry(additionalData).Property(x => x.AmountPaid).IsModified = true;
    dbContext.SaveChanges();
}

内容的提问来源于stack exchange，提问作者Surendra