Question

I have the following 2 mappings:

internal RulesEngineHeaderMap()
{
    Table("LIOEP023");

    CompositeId()
        .KeyProperty(x => x.CompanyCode, "CONO23")
        .KeyProperty(x => x.RuleID, "RLID23");
    Map(x => x.RuleGroup, "RGRP23")
        .Length(30)
        .Not.Nullable();
    Map(x => x.RuleDescription, "RLDS23")
        .Length(50)
        .Not.Nullable();
    Map(x => x.Expression, "EXPR23")
        .Length(2500)
        .Not.Nullable();
    HasMany(x => x.RuleVariables)
        .KeyColumns.Add("CONO24", "RLID24");
}

and

internal RulesEngineVariableDetailMap()
{
    Table("LIOEP024");
    CompositeId()
        .KeyProperty(x => x.CompanyCode, "CONO24")
        .KeyProperty(x => x.RuleID, "RLID24")
        .KeyProperty(x => x.Name, "RVAR24");
    Map(x => x.Type, "VTYP24")
        .Not.Nullable();
    Map(x => x.Description, "VDES24")
        .Not.Nullable();
    Map(x => x.Required, "RMAN24")
        .Not.Nullable();
    References(x => x.RuleHeader)
        .Columns("CONO24", "RLID24")
        .NotFound.Ignore()
        .Nullable();
}

When I try and add a new object into the RuleVariables IList of RulesEngineHeader and update, I get the error

Batch update returned unexpected row count from update; 
  actual row count: 0; expected: 1

When I look at my SQL, I’m seeing this:

SELECT rulevariab0_.CONO24 as CONO1_1_,
    rulevariab0_.RLID24 as RLID2_1_,
    rulevariab0_.RVAR24 as RVAR3_1_,
    rulevariab0_.CONO24 as CONO1_1_0_,
    rulevariab0_.RLID24 as RLID2_1_0_,
    rulevariab0_.RVAR24 as RVAR3_1_0_,
    rulevariab0_.VTYP24 as VTYP4_1_0_,
    rulevariab0_.VDES24 as VDES5_1_0_,
    rulevariab0_.RMAN24 as RMAN6_1_0_
FROM   LIOEP024 rulevariab0_
WHERE  rulevariab0_.CONO24 = 'LO' /* @p0 */     <-- KEY FIELD
    and rulevariab0_.RLID24 = 'Test' /* @p1 */  <-- KEY FIELD

The where clause only contains 2 of the 3 key fields that I defined, so it’s finding the record and trying to update, but then the update looks like this:

UPDATE LIOEP024
SET    CONO24 = 'LO' /* @p0_0 */,
    RLID24 = 'Test' /* @p1_0 */
WHERE  CONO24 = 'LO' /* @p2_0 */         <-- KEY FIELD
    AND RLID24 = 'Test' /* @p3_0 */      <-- KEY FIELD
    AND RVAR24 = 'Some Name' /* @p4_0 */ <-- KEY FIELD

As you can see, it’s using all 3 of the key fields. It should be doing an insert here instead, but since the select above found the record, it thinks it should do an update, which is returning 0 records.

Any ideas what I’m doing wrong here?

Answer 1

You are using a composite key for RuleVariable. NHibernate has no way of knowing whether your RuleVariable is a new instance or an existing one. If you used a generated id like identity, then it could tell by checking whether the id was > 0.

You need to tell NHibernate that your new RuleVariable is a new instance, ie. you need to persist the RuleVariable before you save the Header, to do so, call session.Save(variable)