Entity Framework 第十篇 条件查询

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();
}