Take care and Thanks alot

(sorry if the wrong place to post)

If your need is urgent, you might have better luck on the NHUsers forum where there are more people can assist you ( http://groups.google.com/group/nhusers ).

I can advise in advance that you’re going to need to be able to provide some or all of the following in order for either myself or anyone else to be able to assist you:

* class file(s) for persisted objects
* mapping (.hbm) files for objects

Best of luck~!

-Steve B.

{”could not initialize a collection: [FECCGe.Core.Student.Domains#1][SQL: SELECT domains0_.ID_Student as ID2_1_, domains0_.ID_Materie as ID1_1_, domain1_.ID_Materie as ID1_1_0_, domain1_.Materie as Materie1_0_, domain1_.ID_Specializare as ID3_1_0_, domain1_.AnUniversitar as AnUniver4_1_0_ FROM Student_Materie domains0_ left outer join Materie domain1_ on domains0_.ID_Materie=domain1_.ID_Materie WHERE domains0_.ID_Student=?]“} System.Exception {NHibernate.Exceptions.GenericADOException}
and it’s inner exception message is : “No value given for one or more required parameters.” and as you see for yourself, I don’t parse anything for the ID_Student column.

The way I’m retrieving the Order (like in your example) is this :
return _session.Get(studentId);

Do you know what’s wrong or am I doing something wrong with NHibernate.

Please answer, it’s kind of urgent !

You are (I think) in luck. Step 1 you have already identified as being to make the default (empty) constructor private. Step 2 however is to do something that I didn’t begin to go into in any of the screencasts: tell nhib to use the private backing fields for your properties instead of the properties themselves.

You need a combination of access=”field” on your property, id, etc. tags and also investigate ‘naming strategies’ so that nhib can properly deduce the name of your backing fields from your property names. This set of steps will allow nhib to access your underlying private data members NOT via your property accessors.

This screencast touches immutability a little so here is the most apt place to ask the following question:

I am currently tasked with introducing NHibernate into our codebase. All of our business domain objects are immutable and take the following format:

public class SampleEntity
{
public readonly int SampleProperty;
public readonly string SampleProperty2;

public SampleEntity(int sp1, string sp2)
{
this.SampleProperty = sp1;
this.SampleProperty2 = sp2;
}

From what I can see, we would have to perform the following to make our entites NHibernate compatible but as close as possible to still being immutable “enough”:

1. Add a default constructor (it can be private but still needs to be added)
2. Take the readonly attribute off all properties and have get; private set; accessibility.

Is there any way to get NHibernate to work with an antity of the type described above?

In my opinion, we shoudnt have to sacrifice our business domain objects “immutability” to cater for an ORM integration.

Also, I know another solution could be to map our immutable business domain entities to NHibernate compatible entities but this in my opinion would be too costly!

So in conclusion , is there a way to get HNibernate to work for “truely” (i.e. using readonly properties) immutable types?

In comment #22 Wordpress stripped out my thing-in-anglebrackets in that last sentence that was supposed to read “NHhibernate + your-database-here + updateable view”.

I keep forgetting that Wordpress just drops anything that contains HTML-style angle brackets

You are correct (sort of). Various DB platforms have varying support for what are called ‘updateable views’ where you can actually use a view as a read-write target instead of just a read-only target. Different DB targets impose different constraints on what must be ‘true’ for a view to be updateable and still other DB platforms don’t support updateable views at all.

Given all this, unless you are 100% certain of the DB your NHib-based app will run against, its really best-practice not to make a design decision (like to depend on updateable views) unless you are willing to sacrifice DB-platform-neutrality (one of the main reasons for selecting and O/RM tool like NHib in the first place).

That said, if you decide that tying your solution to a particular DB target is OK for your app, then google on NHibernate + + “updateable view” and you will certainly find plenty of info out there.

if i understood correctly the purpose of using “view” is for “read only”?

great videos and learn a lot and today whole day i was watching your videos and i’m on 8th video now

Seems that the angle-brackets from my prior comment (#19) were stripped out of the comment. The mapping tag that I was TRYING to suggest you investigate there is called ‘joined-subclass’. In the prior post, every time the sentence doesn’t seem to make sense, insert the text ‘joined-subclass’ into the sentence and it will be fine

Wordpress seems to want to strip angle-brackets out of comments, presumably to protect me from aberrent HTML entered as comments.