Entity Framework 第十篇 条件查询

Posted 2020-07-28 尘嚣之上

业务类中 我们根据条件来动态的查询

创建IQueryable接口

 public IQueryable<TEntity> GetQueryable()
        {
            IQueryable<TEntity> query = dbContext.Set<TEntity>();
            return query;
        }

 

为什么创建IQueryable接口？IQueryable会在调用ToList()或者Count()等方法的时候，才回向数据库查询，所以只会向数据库提交一次带条件的查询语句，从而提升了性能。

 

 public IList<Shop> Query(Shop model)
        {

            IQueryable<Shop> query = GetQueryable().Where(m => m.DelStatus == 0);
            if (model.ShopID != null)
            {
                query = query.Where(m => m.ShopID == model.ShopID);
            }
            if (!string.IsNullOrEmpty(model.Name))
            {
                query = query.Where(m => m.Name.Contains(model.Name));
            }
            if (!string.IsNullOrEmpty(model.Province))
            {
                query = query.Where(m => m.Province == model.Province);
            }
            if (!string.IsNullOrEmpty(model.City))
            {
                query = query.Where(m => m.City == model.City);
            }
            if (!string.IsNullOrEmpty(model.Area))
            {
                query = query.Where(m => m.Area == model.Area);
            }
            query = query.OrderBy(m => m.ShopID);
            return query.ToList();

        }