[CSHARP-140] Hide hierarchy discriminator in query when anonymous type is used for wrapping. Created: 22/Dec/10  Updated: 02/Apr/15  Resolved: 27/Dec/10

Status: Closed
Project: C# Driver
Component/s: None
Affects Version/s: 0.9
Fix Version/s: 1.0

Type: Improvement Priority: Major - P3
Reporter: Timofei Mironov Assignee: Robert Stam
Resolution: Done Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified
Environment:

MongoDB v 1.6.3
C# Driver version: both Bison and Driver 0.9.1 (from github)



 Description   

Here is sample code firstly:
----------------------------------------
A a = new A();
a.b = "asd1";
a.c = "asd2";

db.GetCollection<A>("A").Insert(a);

var o1 = db.GetCollection<A>("A").FindOneAs<A>(Query.Wrap(new

{ c = "asd2" }));

object selector = new { c = "asd2" }

;
var o2 = db.GetCollection<A>("A").FindOneAs<A>(Query.Wrap(selector));

Assert.IsNotNull(o1); // Success
Assert.IsNotNull(o2); // Fail
----------------------------------------

The problem is when I want to use anonymous type instance as a selector for wrapping query.
Getting o1 I use it in a place of calling, so actualType and nominalType are equals and driver does not insert hierarhy discriminator into query.
sometimes I want to pass filter as argument for functions, so this case anonymous type insance casted to object, so actualType and nominalType are differ, and driver adds discriminator according to this code:

BsonClassMapSerialzier.Serialize(..) line 175.
----------------------------------------
if (actualType != nominalType || classMap.DiscriminatorIsRequired || classMap.HasRootClass) {
var discriminatorConvention = BsonDefaultSerializer.LookupDiscriminatorConvention(nominalType);
var discriminator = discriminatorConvention.GetDiscriminator(nominalType, actualType);
if (discriminator != null)

{ bsonWriter.WriteName(discriminatorConvention.ElementName); discriminator.WriteTo(bsonWriter); }

}
----------------------------------------

I think it would be better if no descriminator applied when using anonymous instance as a subject for wrapping.



 Comments   
Comment by Robert Stam [ 27/Dec/10 ]

We now never serialize a discriminator for anonymous classes or wrapped objects (with the exception of Update.Replace).

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