一、简化查询1. 先看一下查询的例子////// 账户获取服务/////////public class AccountGetService(AccountTable table, IShadowBuilder builder){private readonly SqlSource _source new(builder.DataSource);private readonly IParamQuery _accountQuery builder.BuildResult(table.ToQuery().And(account account.Id.Equal()).ToSelect().SelectSelfColumns());////// 获取账户////////////public Task GetAsync(Account param, CancellationToken token default) _accountQuery.GetFirstAsync(_source, param, token);}2. 调用方式如下var account await accountGetService.GetAsync(new Account { Id 1L });3. 这个例子我们可以简化一下参数直接使用Id(类型由Account简化为long)很大一部分数据库操作都只有一个参数(GetById、GetByName等)为此定义一个含单个属性类有点浪费按上面的例子使用实体类作为参数也感觉怪怪的DBShadow.net支持这种简化操作单个参数无需封装,直接使用参数类型即可public class AccountGetService(AccountTable table, IShadowBuilder builder){private readonly SqlSource _source new(builder.DataSource);private readonly IParamQuery _accountQuery builder.BuildResult(table.ToQuery().And(account account.Id.Equal()).ToSelect().SelectSelfColumns());public Task GetAsync(long accountId, CancellationToken token default) _accountQuery.GetFirstAsync(_source, param, token);}var account await accountGetService.GetAsync(1L);4. 特别注意不要在Dapper中这样使用Dapper是不支持这种简化操作以下Dapper错误示例会抛出异常System.InvalidOperationException:“Must add values for the following parameters: Id”await using var conn _dataSource.CreateConnection();var sql SELECT \Id\,\Title\,\Content\,\Done\,\LastTime\ FROM \Todo\ WHERE \Id\Id;var first await conn.QueryFirstOrDefaultAsync(sql, 1L);二、 集合参数也支持简化操作1. IN查询简化的例子In的参数名是可选和前面例子的Equal是一样的,默认字段名In查询的实参支持数组、集合及字典只有In一个集合参数时支持直接传数组、集合或字典这时参数名(eg: AccountIds)就无所谓取什么名了因为不需要按参数名反射获取属性了////// 批量账户获取服务/////////public class AccountBatchService(AccountTable table, IShadowBuilder builder){private readonly SqlSource _source new(builder.DataSource);private readonly IParamQuery _accountQuery builder.BuildResult(table.ToQuery().And(account account.Id.In(AccountIds)).ToSelect().SelectSelfColumns());////// 批量获取账户////////////public IAsyncEnumerable GetAsync(long[] accountIds, CancellationToken token default) _accountQuery.QueryAsync(_source, accountIds, token);}2. 以上调用的例子如下[Fact]public async Task Batch(){var count 0;var service new AccountBatchService(table, builder);var list service.GetAsync([1L, 2L, 3L]);await foreach (var item in list){_output.WriteLine(${item.Id}:{item.Amount});count;}Assert.Equal(3, count);}// 1:100// 2:200// 3:300三、泛型查询1. 泛型服务类代码该服务用来按字段Id查询表Account参数TParam是泛型,这样可以直接使用DTO参数来查询,减少类型转化的开销返回值TAccount也是泛型,这样就可以直接返回视图模型或者领域模型这样的泛型服务类就非常的通用////// 账户获取泛型服务/////////public class AccountGetService(AccountTable table, IShadowBuilder builder){private readonly SqlSource _source new(builder.DataSource);private readonly IParamQuery _accountQuery builder.BuildResult(table.ToQuery().And(account account.Id.Equal()).ToSelect().SelectSelfColumns());////// 获取账户////////////public Task GetAsync(TParam param, CancellationToken token default) _accountQuery.GetFirstAsync(_source, param, token);}2. 中规中矩的调用方式var service new AccountGetService(_table, _builder);var account await service.GetAsync(new Account { Id 1L });Assert.NotNull(account);3. 支持简单调用方式var service new AccountGetService(_table, _builder);var account await service.GetAsync(1L);Assert.NotNull(account);四、总结DBShadow.net预编译比较智能只有1个参数时支持化繁为简,支持直接传值做为参数值这样可以节约定义只有一个属性的参数类参数和返回值类型还可以定义为泛型,可以做到更加灵活烦诖悠欢