Linq to Sql在Where子句中为null [英] Linq to Sql is null in Where clause

问题描述

如果Sessions.Current.AdminProductId为null，是否可以忽略Where子句?我想将下面的代码优化为一行代码.

Is it possible to ignore Where clause if Sessions.Current.AdminProductId is null? I would like to optimize code below into one line of code.

if (Sessions.Current.AdminProductId == null)
  gvUsers.DataSource = DataAccess.Instance.Users;
else
  gvUsers.DataSource = DataAccess.Instance.Users.Where(p => p.Orders.Any(o => o.ProductId == Sessions.Current.AdminProductId));

推荐答案

您只需要在where子句中添加null检查，就像这样:

You just need to add the null check in the where clause like this:

 gvUsers.DataSource = DataAccess.Instance.Users.Where(p => (Sessions.Current.AdminProductId == null) || (Sessions.Current.AdminProductId != null && p.Orders.Any(o => o.ProductId == Sessions.Current.AdminProductId)));

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