Repository简化实现多条件查询
Repository 在做查询的时候,如果查询条件多的话,linq
查询表达式会写的很复杂,比如:
江达ssl适用于网站、小程序/APP、API接口等需要进行数据传输应用场景,ssl证书未来市场广阔!成为成都创新互联的ssl证书销售渠道,可以享受市场价格4-6折优惠!如果有意向欢迎电话联系或者加微信:18982081108(备注:SSL证书合作)期待与您的合作!
public IQueryableGet(int id, string name, string address, Status? status, DateTime createTime) { var query = _entities; if(id != 0) { query = query.where(x => x.Id == id); } if(!string.IsNullOrWhiteSpace(name)) { query = query.where(x => x.Name.Contains(name)); } if(!string.IsNullOrWhiteSpace(address)) { query = query.where(x => x.Address.Contains(address)); } if(status.HasValue) { query = query.where(x => x.Status == status.Value); } if(createTime != null) { query = query.where(x => x.CreateTime == createTime); } // ... return query; }
可以看到,查询条件多的话,我们会写很多的if
判断,代码看起来很不美观,解决方式使用Expression
,示例代码:
using System.Linq.Expressions; public IQueryableGet(int id, string name, string address, Status? status, DateTime createTime) { Expression > studentFunc = x => (id == 0 || x.Id == id) && (string.IsNullOrWhiteSpace(name) || x.Name.Contains(name)) && (string.IsNullOrWhiteSpace(address) || x.Address.Contains(address)) && (!status.HasValue || x.Status == status.Value) && (createTime == null || x.CreateTime <= createTime); return _entities.Where(studentFunc); }
生成示例sql
代码:
SELECT `x`.`id`, `x`.`name`, `x`.`address`, `x`.`status`, `x`.`create_time` FROM `students` AS `x` WHERE (`x`.`id` = 2) AND (`x`.`status` = 0) AND (`x`.`create_time` == '2017-04-25T16:24:29.769+08:00'))
网页名称:Repository简化实现多条件查询
分享路径:http://scyanting.com/article/jojpco.html