R – NHibernate Table Update Event

fluent-nhibernatenhibernate

I have this table mapping (details don't really matter I think):

WithTable("COPACKER_FACILITY");  
Id(x => x.FacilityNumber, "FACILITY_NUM").GeneratedBy.Sequence("FACSEQ");
Map(x => x.FacilityName, "FACILITY_NAME").Not.Nullable().Trimmed();
Map(x => x.AddressLine1, "ADDR1").Not.Nullable().Trimmed();
...
WithTable("FACIL_OTH_AUDIT_INFO", m =>
   {
      m.WithKeyColumn("FACILITY_NUM");
      m.Map(x => x.ProdnShiftsNum, "PRODN_SHIFTS_NUM").Not.Nullable();
      m.Map(x => x.ProdnCapacity, "PRODN_CAPACITY").Not.Nullable();
      m.Map(x => x.ProdnLinesNum, "PRODN_LINES_NUM").Not.Nullable();
      m.Map(x => x.AuditScore, "AUDIT_SCORE");
      m.References(x => x.FacilStatus, "STATUS_IND").Not.Nullable();
   });
HasMany(x => x.ComplianceFlags)
   .KeyColumnNames.Add("FACILITY_NUM")
   .Inverse()
   .Cascade.All();
...

The reason for the one to one table is for audit reasons. There's a FACIL_OTH_AUDIT_INFO_HIST table that should get a record for every insert and update in the main table.

My question: How can I know when an insert or update happens in that table so I know to insert an audit record?

Many thanks!

Best Answer

+1 to what kvalcanti said... here's another post that I think explains it a little better though (and shows you how to do it without XML configuration!). I'm doing what this guy is doing on my project and it's working really well.

http://www.codinginstinct.com/2008/04/nhibernate-20-events-and-listeners.html

Caveat: I'm not inserting new objects that need to be saved in this event in my project, which I assume will not be a problem, but I can't say for sure since I'm not doing exactly what you're doing.

Related Solutions

Fluent NHibernate: How to create one-to-many bidirectional mapping

To get a bidirectional association with a not-null foreign key column in the Details table you can add the suggested Owner property, a References(...).CanNotBeNull() mapping in the DetailsMap class, and make the Summary end inverse.

To avoid having two different foreign key columns for the two association directions, you can either specify the column names manually or name the properties in a way that gives the same column name for both directions. In this case you I suggest renaming the Details.Owner property to Details.Summary.

I made the Summary id generated by increment to avoid problems when inserting into the table since Summary currenty has no columns besides id.

Domain:

public class Detail
{
    public int id { get; protected set; }
    public string ItemName { get; set; }

    // Renamed to use same column name as specified in the mapping of Summary.Details
    public Summary Summary {get; set;} 
}

public class Summary
{
    public Summary()
    {
        Details = new List<Detail>();
    }

    public int id { get; protected set; }
    public IList<Detail> Details { get; protected set; }
}

Mapping:

public class DetailMap : ClassMap<Detail>
{
    public DetailMap()
    {
        Id(x => x.id)
            .GeneratedBy.Native();

        Map(x => x.ItemName)
            .CanNotBeNull();

        References<Summary>(x => x.Summary)
            // If you don't want to rename the property in Summary,
            // you can do this instead:
            // .TheColumnNameIs("Summary_id")
            .CanNotBeNull();
    }
}

public class SummaryMap : ClassMap<Summary>
{
    public SummaryMap()
    {
        Id(x => x.id)
            .GeneratedBy.Increment();

        HasMany<Detail>(x => x.Details)
            .IsInverse()
            .AsBag(); // Use bag instead of list to avoid index updating issues
    }
}

C# – NHibernate additional UPDATE query run

From the docs: inverse (optional - defaults to false): If enabled, Hibernate will not try to insert or update the properties defined by this join.

My suggestion: In some cases to prevent additional updates with 2-way joins BOTH collections may need to be updated:

Contact c;
Address a;    
c.Addresses.Add(a);
a.Contacts.Add(c);

You are probably getting the additional Update statement because both sides have inverse=false and the first entity's relationship list was saved empty. NH is only doing what it thinks it needs to in order to get all relationships updated.

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