NHibernate ERROR Message Invalid index 4 for this SqlParameterCollection with Count=4

Question

NHibernate ERROR Message Invalid index 4 for this SqlParameterCollection with Count=4.

My Mapping:

public KazangAccountClassMap()
{
    Table("KazangAccount");
    Id(x => x.Id).GeneratedBy.Identity();
    Map(x => x.Channel).Not.Nullable();
    Map(x => x.UserName).Not.Nullable();
    Map(x => x.Password).Not.Nullable();
    HasMany<KazangMerchant>(x => x.KazangMerchants)
      .KeyColumn("AccountId")
      .Inverse();
}

CONTROLLER:

public ActionResult SaveChannelProperty(string NewProp, string ChannelName)
{
    client.CreateKazangChannelAttribute(new KazangChannelAttr
    {
        KazangChannelId = ChannelObject.Id,
        AttrName = NewProp,
        AttrValue = NewProp,
        AttrType = ""          
    });
}

This error is simple to find and also simple to fix, but please, show the full exception stack trace and the mapping related to that error. — Radim Köhler
– Radim Köhler, Commented Jan 12, 2015 at 13:18

Radim Köhler · Accepted Answer · 2015-01-12 13:28:37Z

5

This kind of exception is almost always related to "doubled" mapping. Because from the snippets shown in the quesiton it is not easy to show, I would explain it like this:

Let's have an entity KazangAccount, which has reference to Channel and also int representation of that object as ChannelId

public class KazangAccount
{
    public virtual int Id { get; set; }
    ...
    public virtual Channel Channel { get; set; }
    public virtual int ChannelId { get; set; }
}

In this case, we would be intstructing NHibernate to use ONE column for TWO properties - and that would not work:

public KazangAccountClassMap()
{
    ...
    References(x => x.Channel)
       .Column("Channel_ID"); // the Channel reference
    Map(x => x.ChannelId)
       .Column("Channel_ID");      // the int property ChannleId

That mapping is good for any READ operation... column will be used twice. But for WRITE operation, we would create params for column Channel_ID and another for column Channel_ID == only one of them will be created. And while NHibernate expects some count of params - there is one missing.

Solution? Make one of these read-only

public KazangAccountClassMap()
{
    ...
    References(x => x.Channel)
       .Column("Channel_ID"); // READ and WRITE
    Map(x => x.ChannelId)
       .Column("Channel_ID")  // just READ
       .ReadOnly()            // insert="false" update="false"
       ;

Now, NHibernate will create/expect only one column/sqlParamter for this column...

answered Jan 12, 2015 at 13:28

Radim Köhler

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2 Comments

alphanoch Over a year ago

As said in answer problem is related to double mapping. In my case it was in SubclassMap. Each "SubClass" was mapping the same base property.

Radim Köhler Over a year ago

Good if you've found the way... ;)

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