R – Can we stop the ID column from auto-incrementing

fluent-nhibernate

I have a table with primary column as an ID. But that column is not an identity column. All the values are provided explicitly.

Below is my mapping class

 public ObjectTypeMap()
    {
        Table("OBJECTTYPE");
        Id(x => x.ObjectTypeId);
        Map(x => x.Title).Not.Nullable();
        Map(x => x.Description);
    }

but when I try to save this object using session.save, I get an error saying

"Cannot insert the value NULL into column 'ObjectTypeId', table 'DiscoveryWEBTest.dbo.ObjectType'; column does not allow nulls. INSERT fails.\r\nThe statement has been terminated."

But in my object I am providing the value of ObjectTypeId.

The problem is Fluent NHibernate considers ID mapping as auto-increment column, but in the database ObjectTypeId is not an identity column thats why the insert statement do not get any value and throws null error.

Is there a way with which I can tell the the column is an ID column but its value is not auto-incremented?

Thanks in advance

Best Answer

Map it like this:

Id(x => x.ObjectTypeId).GeneratedBy.Assigned();

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
    }
}

NHibernate: Using Fluent Nhibernate to save child objects

I had this exact problem with fluent nhibernate. There appears to be a small bug in mapping one-to-many relationships and the relationships not automatically saving or cascading. See here for a posting about it on the Fluent NHibernate group.

Apparently, there is someone working on the issue!

I can;t say for sure that this is the issue with your code but it looks very similar to a problem I had. Hope that helps some!

Best Answer

Related Solutions

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

NHibernate: Using Fluent Nhibernate to save child objects

Related Topic