EFCore扩展Select⽅法(根据实体定制查询语句)EFCore扩展Select⽅法(根据实体定制查询语句)通常⽤操作数据库的时候查询返回的字段是跟我们的定义的实体是不⼀致的,所以往往针对UI或者接⼝层创建⼤量的Model, ⽽且需要⼿动对应字段,⾮常繁琐。本⽂将通过表达式树解决这些重复的过程。先贴上实现代码 ...
}publicstaticMemberInitExpression GetExpression(Expression parameter, Type sourceType, Type targetType) {varmemberBindings =newList<MemberBinding>();foreach(vartargetItemintargetType.GetProperties().Where(x =>x.CanWrite)) {varfromEntityAttr = targetItem.GetCustomAttribute<FromEntityAttribute>();if(fromEnti...
; } public static MemberInitExpression GetExpression(Expression parameter, Type sourceType, Type targetType) { var memberBindings = new List<MemberBinding>(); foreach (var targetItem in targetType.GetProperties().Where(x => x.CanWrite)) { var fromEntityAttr = targetItem.GetCustomAttribute<FromEntit...
如果您具有自定义投影Select,则Include将被完全忽略,因此您的过滤器也将被忽略。这不是一个错误,只有...
EFCore扩展Select方法(自动映射自定义实体) 通常用操作数据库的时候查询返回的字段是跟 我们的定义的实体是不一致的,所以往往针对UI或者接口层创建大量的Model, 而且需要手动对应字段,非常繁琐。 本文将通过表达式树解决这些重复的过程。 先贴上实现代码 Queryable 类中 的扩展方法 Select<TSource, TResult>(this IQu...
(1) EFCore删除必须先查询再删除,优化后可直接删除:context.User.Where(t => t.Id == 100).Delete; 3、正确使用Find(id=10)来代替FirstOrDefault(t=>t.id=10) Find会优先查询缓存,当前面已经查询过这条数据的时候使用,而FirstOrDefault每次都会查询数据库;当id=10的数据被修改之后,find查出的数据是新数...
ToTimeZone(thisDateTime?source,string timeZone){if(!source.HasValue)returnnull;vartz=TimeZoneInfo....
I'm trying to "translate" in EF core this SQL query: SELECT * FROM Estrazioni WHERE Estrazioni.DataEstrazione = (SELECT MAX(maxEstrazione.DataEstrazione) FROM Estrazioni AS maxEstrazione) I have tried to write this, copying from internet, but I receive a lot of error that I don't understa...
varcities = _dbContext.Cities.Select(city=>newCityViewModel() { Code = city.Code, CityName = city.Name }).ToList(); 那么现在,愉快的使用它吧: varcities = _dbContext.Cities.Select<City, CityViewModel>().ToList(); EFCore自动生成的脚本如下图(并没有查询Id和ProvinceId)...
19 EF Core Single vs. Split Queries 0 The background task I am running in my asp.net application is taking long time to execute and is getting stuck at a linq query Related 1 FirstOrDefault() || Select() which is faster? 135 Entity Framework 4 Single() vs First() vs Fir...