RavenDb Strange Behaviour with objects with equality members - ravendb

Question

I got to the bottom of a strange bug (in my code ) when I was trying to store a list of objects to ravendb. The problem was that the object to be stored has equality members generated by resharper. The object in question is as follows (note that I have commented out the equality members to solve the issue) -
//[DataContract(Namespace = "")]
//[KnownType(typeof(IApplicationEntity))]
public class ApplicationEntity: IApplicationEntity
{
public ApplicationEntity()
{
}
public ApplicationEntity(string processName)
{
ProcessName = processName;
Id = "Processes/" + ProcessName;
}
public ApplicationEntity(string key, string processName)
{
ProcessName = processName;
Key = key;
Id = string.Format("Processes/{0}_{1}", Key, ProcessName);
}
//[DataMember]
public string Id { get; set; }
//[DataMember]
public string Key { get; set; }
//[DataMember]
public string ProcessName { get; set; }
//[DataMember]
public string ProcessDescription { get; set; }
/// <summary>
/// used to generate sequential unique activity ID generation only.
/// </summary>
//[DataMember]
public string ActivityCount { get; set; }
//public bool Equals(ApplicationEntity other)
//{
// if (ReferenceEquals(null, other)) return false;
// if (ReferenceEquals(this, other)) return true;
// return Equals(other.ProcessName, ProcessName);
//}
//public override bool Equals(object obj)
//{
// if (ReferenceEquals(null, obj)) return false;
// if (ReferenceEquals(this, obj)) return true;
// if (obj.GetType() != typeof (ApplicationEntity)) return false;
// return Equals((ApplicationEntity) obj);
//}
//public override int GetHashCode()
//{
// return (ProcessName != null ? ProcessName.GetHashCode() : 0);
//}
}
Now if I stored the object with equality members implement then the following code produces strange results -
int count = 0;
using (var session = _store.OpenSession(_databaseName))
{
foreach (var applicationEntity in _listOfApplications)
{
var entity = new ApplicationEntity(count.ToString(), applicationEntity.ProcessName);
//ravenRepositoryCachable.Add(entity);
session.Store(entity);
count++;
}
session.SaveChanges();
}
The strange behaviour is that I would expect the Key field to be incrementing to 400 as the list has 400 members , but instead the Key for the first 10 object stored is correct i.e 0 to 9. but the 11th one started from 0 again and so on.
but if I comment the equality members off(as in the code snippet above) then this problem disappears.
Also If i add the objects one at a time as opposed to batch the problem disappears -
int count = 0;
foreach (var applicationEntity in _listOfApplications)
{
using (var session = _store.OpenSession(_databaseName))
{
var entity = new ApplicationEntity(count.ToString(), applicationEntity.ProcessName);
//ravenRepositoryCachable.Add(entity);
session.Store(entity);
session.SaveChanges();
count++;
}
}
I know I have resolved the issue but I do not understand what happened here and why only the key field was effected? This is a undefined behaviour and I am worried as bit as code is supposed to be deployed in production!! It is clear that the equality members are not to be defined. I need to get to the bottom of it , is it a bug?

Answer 1

No, I don't think there is such a bug in RavenDB. Instead, I guess there is another issue with your code, because this test (that is based on your example above) works for me:
public class EqualityMembersInSessionCache
{
public class ApplicationEntity
{
public ApplicationEntity(string key, string processName)
{
ProcessName = processName;
Key = key;
Id = string.Format("Processes/{0}_{1}", Key, ProcessName);
}
public string Id { get; set; }
public string Key { get; set; }
public string ProcessName { get; set; }
public bool Equals(ApplicationEntity other)
{
if (ReferenceEquals(null, other)) return false;
if (ReferenceEquals(this, other)) return true;
return Equals(other.ProcessName, ProcessName);
}
public override bool Equals(object obj)
{
if (ReferenceEquals(null, obj)) return false;
if (ReferenceEquals(this, obj)) return true;
if (obj.GetType() != typeof(ApplicationEntity)) return false;
return Equals((ApplicationEntity)obj);
}
public override int GetHashCode()
{
return (ProcessName != null ? ProcessName.GetHashCode() : 0);
}
}
[Fact]
public void Has_correct_behaviour()
{
var randomNames = new List<string>();
for (int c = 1; c < 100; c++)
{
randomNames.Add(string.Format("test{0}", c));
}
using (var store = new EmbeddableDocumentStore { RunInMemory = true })
{
int count = 0;
using (var session = store.OpenSession())
{
foreach (var name in randomNames)
{
session.Store(new ApplicationEntity(count.ToString(), name));
count++;
}
session.SaveChanges();
}
using (var session = store.OpenSession())
{
var results = session.Query<ApplicationEntity>()
.Customize(x => x.WaitForNonStaleResultsAsOfLastWrite())
.ToList();
Assert.NotEmpty(results);
Assert.Equal(99, results.Count);
for (int c = 0; c < 99; c++)
{
Assert.Equal(c, int.Parse(results[c].Key));
}
}
}
}
}
If you want us to investigate further on this, please provide a failing test.