如何使用C#MongoDB驱动程序检索字段子集？

Question

我在世界各地搜索过,似乎无法找到答案.

我如何在C#中执行此操作:

// retrieve ssn field for documents where last_name == 'Smith':
db.users.find({last_name: 'Smith'}, {'ssn': 1});

谢谢!

Answer 1

包括:

.SetFields(Fields.Include("first_name", "last_name"));

要排除字段:

.SetFields(Fields.Exclude("SSN","Salary"));

要做到两件事:

.SetFields(Fields.Include("first_name", "last_name").Exclude("SSN","Salary"));

Answer 2

请注意,您现在可以使用(类型/重构)-safe版本:

usersCollection.FindAllAs<User>()
               .SetFields(Fields<User>.Include(user => user.FirstName,
                                               user => user.LastName)
                                      .Exclude(user => user.SSN)
               .ToArray();