Hi everybody,

I have 2 tables : Departments and Staffs
Departments : DepartmentID, Name
Staffs : StaffID, Name, DepartmentID

When I use some templates to create my mapping and persistent files.
I receive the following mapping file :

<property name="StaffID" column="StaffID" type="int" not-null="true" />
<property name="StaffName" column="StaffName" type="string" not-null="true" />

<many-to-one name="Department" column="DepartmentID " />

And here is persistent class file :

protected int _staffID;
protected string_name;
protected Department _department;

protected int StaffID
{
get {return this._staffID;}
set {this._staffID=value;}
}

protected int Name
{
get {return this._name;}
set {this._name=value;}
}

public virtual Departments Department
{
get { return _department; }
set {_department = value; }
}

I want to update or insert a new staff :

Staffs st=new Staffs();

st.StaffID = 1;
st.StaffName = "Test";

How can I update DepartmentID for this staff. Because in persistent class does not have DepartmentID property. It just has Department - I think this is the Departments class.

Pls help me do this.

Thanks so much.

Um...Update the 'ID' property in the Department class.
'DepartmentID' is not a property in an object but rather a column in your DB table. This tells NHibernate which Department values to hydrate an Department for your Staff class.

NHibernate is creating an association to an object called Department.

BTW...unless you are constrained to do so, I'd avoid using the assignment strategy for ID fields and instead let the db handled the constraints/associations with, say, autoincrementing fields.

But maybe you have some constraint not allowing this.

Why don't you use a regular key for mapping? It could look like the following:



Also you don't need operate the dept id, do you? Let the NH do it for you. Is there any reason for doin it your way?

BTW - there is a space character in your mapping for the dept id column...

Thanks for your response!

I am newbie in Nhibernate so I do not understand the data is inserted or updated.

For example :

I'd like to insert a new staff I'll do that :

Staffs st=new Staffs();

I can set :

st.StaffID = 1;
st.StaffName = "Test";

How about field DepartmentID for this staff. How can I set value for it?
Because I can not set value for it normally :

st.DepartmentID = dropdownlist1.SelectedValue; // It does not have DepartmentID property.

Could you give me the explanation for this.

Thanks a lot.

You don't need the ID. Assuming you have a persisted instance of Department, you simply assign it like the following:





You will do it this way:


Hope this helps

The way I would think of solving this problem is to have one other property called DepartmentId that comes handy to me to just set the DepartmentId (just the value and not the whole entity itself - saves me from loading the Department if I dont have one in the cache). And mark the Department property with update="false" insert="false".

<property name="StaffID" column="StaffID" type="int" not-null="true" />
<property name="StaffName" column="StaffName" type="string" not-null="true" />
<property name="DepartmentID" column="DepartmentID" type="string" not-null="true" />

<many-to-one name="Department" column="DepartmentID" class="Depart, ..." update="false" insert="false" />

By this you achieve twin benefits:
1. No need to have whole Department Entity to update/save.
2. You can get the whole Department while reading the Staff.

Hope this helps!