NHibernate Criteria API error with create alias and a collection of projections

Question

I'm tasked with generating a list of member data using the NHibernate Criteria API. I need to incorporate paging and filtering based on checkboxes in the UI. What makes this a bit more complex is that I'm not just fetching data from one entity, but this entity has a HasMany relationship to other entities.

I currently have an error:

Error executing multi Criteria: 
[SELECT DISTINCT TOP 1000 this_MemberID as y0_ 
 FROM _Members
 Left Outer Join _SubMemberTerms ON _SubMemberTerms.MemberID = this_.MemberID
 Left Outer Join _MemberTerms ON _MemberTerms.MemberID = this_.MemberID
 Left Outer Join _ScriptOption ON _ScriptOption.ID = _MemberTerms.ScriptOpID
 WHERE _MagazineID = 100
 AND 
    (_ScriptOption.MagID IN (1234,5678,9101,.....) 
        OR _ScriptOption.MemberID IS NULL
        OR _ScriptOption.Active = 0)
 AND
    (_SubMemberTerms._ScriptOpID IN (1234,5678,9101,.....)
        OR _SubMemberTerms.ID IS NULL);]

The Inner exception is: The value \"5554302\" is not of type \"MyBusiness.MemberInfo\" and cannot be used in this generic collection. Parameter name: value.

Right now I'm just looking at the Member's ID because I commented every other projection in my projection list out. Otherwise the error would've stated "The Value \"System.object[]\"...

My Criteria Code:

var filteredList = CurrentSession.CreateCriteria<MemberInfo>("this_")
                   .SetProjection(Projections.Distinct(Projections.ProjectionList()
                   .Add(Projections.Alias(Projections.Property("ManagedMemberID"), "MemberID"))))
                   .Add(Restrictions.Eq("_MagazineID", (int)magID))
                   .CreateAlias("MemTermsList", "_MemberTerms", NHibernate.SqlCommand.JoinType.LeftOuterJoin)
                   .CreateAlias("_MemberTerms.ScriptOpInfo", "_ScriptOption", NHibernate.SqlCommand.JoinType.LeftOuterJoin)
                   .CreateAlias("SubTermsList", "_SubMemberTerms", NHibernate.SqlCommand.JoinType.LeftOuterJoin)
                   .SetFirstResult(startposition)
                   .SetMaxResults(1000);

I also have a Criteria made for getting the count of the total query and not just the 1k returned. It's the same as the Criteria I made for filteredList.

//code for how I'm adding in the MagID's and ScriptOpId's
Disjunction magDisjunction = new Disjunction();
Disjunction subTermsDijunction = new Disjunction();
if(TheCheckBoxThatAppliesIsChecked)
{
    magDisjunction.Add(Restrictions.In("_ScriptOption.MagID", (List<int>)selectedMags))
                  .Add(Restrictions.IsNull("_MemberTerms.MemberID"))
                  .Add(Restrictions.Eq("_MemberTerms.Active", false));

    filteredList.Add(magDisjunction);
}
if(TheOtherCheckBoxThatAppliesIsChecked)
{
    subTermsDisjunction.Add(Restrictions.In("_SubMemberTerms.SciptOpID", (List<int>)selectedScriptOp))
                  .Add(Restrictions.IsNull("_SubMemberTerms.SubMemberTermsID"));

    filteredList.Add(subTermsDisjunction);
}

var finishedList = filteredList.Future<MemberInfo>().ToList<MemberInfo>();
var count = listCount.FutureValue<int>().Value;

EDIT: I had a typo in my projections.Alias, switched form "MemberID", to "ManagedMemberID".

http://stackoverflow.com/questions/318157/get-distinct-result-set-from-nhibernate-using-criteria-api/385079#385079 This is the post that lead me to throwing my distinct propertiesList in the Criteria — CSMHowitzer, Feb 23 '12 at 16:13

score 1 · Accepted Answer · edited May 14 '13 at 13:37

query filteredlist has

.SetProjection(Projections.Distinct(Projections.ProjectionList().Add(Projections.Alias(Projections.Property("MemberID"), "MemberID"))))

which is the same as

.SetProjection(Projections.Distinct(Projections.Property("MemberID")))

which means that the query filteredlist returns MemberID but

var finishedList = filteredList.Future<MemberInfo>().ToList<MemberInfo>();

states that filteredList returns MemberInfo which results in the error

NOTE:

the Future() is just a noop since you are calling ToList() immediatly. change it to

var finishedList = filteredList.Future<int>();
var count = listCount.FutureValue<int>();

to get query batching

Update:

I would get rid of the Projection and use

int count = CriteriaUtil.Clone(query).SetProjection(Projections.RowCount()).FutureValue<int>();
var results = query.Future<MemberInfo>();


View.MemberCount = count.Value;  // executes both sql together here
foreach (MemberInfo result in results)
{
    // do something with the result
}

awesome, I'll try that. I'm about to leave work so I won't get to it until tomorrow. Also the _Projections.Alias(Projections.Property("MemberID"), "MemberID")_, actually is **Projections.Alias(Projections.Property("ManagedMemberID"), "MemberID")**. It was just a typo sorry about that, and now I'll edit the post before I leave. — CSMHowitzer, Feb 23 '12 at 19:19
So what I did was what you mentioned get rid of my "_.ToList_", and now I'm able to run past that line of code. I just need to figure out how to grab that data now. — CSMHowitzer, Feb 24 '12 at 17:59

NHibernate Criteria API error with create alias and a collection of projections

1 Answers1