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Type:
New Feature
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Resolution: Done
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Priority:
Minor - P4
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Affects Version/s: 1.4.2
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Component/s: None
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Fully Compatible
Casting is not currently supported by the linq driver.
We would like the ability to query collections containing derrived types with different properties.
For example
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public class Base
{
public string A { get; set; }
}
public class T1 : Base
{
public string B { get; set; }
}
public class T2 : Base
{
public string C { get; set; }
}
[Test]
public void CastTest()
{
var server = MongoServer.Create("...");
var db = server.GetDatabase("test");
var collection = db.GetCollection<Base>("castTest");
var t1 = new T1 { A = "T1.A", B = "T1.B" };
var t2 = new T2 { A = "T2.A" };
collection.Insert(t1);
collection.Insert(t2);
var query = from t in collection.AsQueryable() where t is T1 && ((T1)t).B == "T1.B" select t;
var results = query.ToList();
Assert.That(results.Count, Is.EqualTo(1));
Assert.That(results[0], Is.InstanceOf(typeof(T1)));
Assert.That(results[0].A, Is.EqualTo("T1.A"));
}
This test currently throws an error
System.NullReferenceException : Object reference not set to an instance of an object. at MongoDB.Driver.Linq.SelectQuery.GetSerializationInfoMember(IBsonSerializer serializer, MemberExpression memberExpression) in C:\work\10gen\mongodb\mongo-csharp-driver\Driver\Linq\Translators\SelectQuery.cs: line 1539
as the Convert expression is not handled.