How to retrieve a subset of fields using the C# MongoDB driver?

Question

I've searched the world over and can't seem to find the answer to this.

How do I do this in C#:

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

Thanks!

OK, well, I was misreading an example elsewhere, but just for the record, here is the solution: users.FindAs(Query.EQ("_id", "test@foo.com")) .SetFields(Fields.Include(new string[] { "first_name", "last_name" })) — Christopher Davies, Jun 30 '11 at 19:52
possible duplicate of [Mongodb -- include or exclude certain elements with c# driver](http://stackoverflow.com/questions/8448179/mongodb-include-or-exclude-certain-elements-with-c-sharp-driver) — i3arnon, Jul 12 '14 at 13:03
Hm. Kind of the other way around, really. This thread is older, but they are dups of each other. — Christopher Davies, Jul 13 '14 at 21:17
The other question has a better answer though, and that's what should count. http://meta.stackoverflow.com/a/252017/885318 — i3arnon, Jul 13 '14 at 21:26

score 16 · Answer 1 · edited Mar 19 '13 at 17:57

16

To include:

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

To exclude fields:

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

To do both:

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

edited Mar 19 '13 at 17:57

Michael Haren

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answered Jul 08 '11 at 23:37

kheya

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score 7 · Accepted Answer · answered Mar 11 '14 at 13:07

Note that you can now use a (type/refactoring)-safe version:

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

How to retrieve a subset of fields using the C# MongoDB driver?

2 Answers2

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