如何在linq查询中添加动态“where”子句? [英] How do you add dynamic 'where' clauses to a linq query?
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问题描述
var users = from d in dc.Users
其中((u.UserRolesBitmask& 1)== 1)
|| ((u.UserRolesBitmask& 4)== 4)
|| ((u.UserRolesBitmask& 16)== 16)
select u;
我想将其重写为以下方法,从给定角色返回所有用户我可以重用它:
私人列表<用户> GetUsersFromRoles(uint [] UserRoles){}
有关如何动态构建查询的任何指针?谢谢
解决方案
您可以使用 PredicateBuilder 类。
PredicateBuilder已在 LINQKit NuGet软件包
LINQKit是一套免费的扩展LINQ to SQL和实体框架的高级用户。
I've got a User table with a bitmask that contains the user's roles. The linq query below returns all the users whose roles include 1, 4 or 16.
var users = from u in dc.Users
where ((u.UserRolesBitmask & 1) == 1)
|| ((u.UserRolesBitmask & 4) == 4)
|| ((u.UserRolesBitmask & 16) == 16)
select u;
I'd like to rewrite this into the method below to returns all the users from the given roles so I can reuse it:
private List<User> GetUsersFromRoles(uint[] UserRoles) {}
Any pointers on how to dynamically build my query? Thanks
解决方案
You can use the PredicateBuilder class.
PredicateBuilder has been released in the LINQKit NuGet package
LINQKit is a free set of extensions for LINQ to SQL and Entity Framework power users.
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