I'm sure I've done this before but I can't recall how. I have 2 classes, say Person and Company. I'm instantiating a new Person and want to set it up so that when I save it to repository it will be associated with Company A. Company A already exists but I don't want to pull the entire thing from the DB just so I can write:
person.Company = CompanyA;
How can I set the Person's Company property so that it will be associated with CompanyA without pulling CompanyA from the DB? I definitely don't want to map the CompanyID property btw!
Use ISession.Load(id). Ayende has a good post about Get vs. Load.
person.Company = session.Load(companyAId);
Related
Working in Spring, and using H2 for now.
So, I have these two classes/Entities with their repositories working fine if I keep it simple.
Brand, which simply has a name and a price;
and VendingMachine, which has a model and some other properties;
BUT I need to implement this:
Different VendingMachines sell different Brands, for which they have a stock. The Brands it sells are determined when you instantiate the class.
So my idea is that the table for VendingMachines fields should look something like that:
MODEL////ID/////MAXCAPACITY////MAXBRANDS///BRAND01////BRAND02///BRAND03...
Where all the BRAND columns are the different Brands the machine sells, assigned at its instantiation as said before. The value will be an Integer.
My original idea was to send this data to the #Entity via a HashMap(Brand, Integer) but I don't know how to make it work once it tries to fit it into the JpaRepository, or even if it is possible this way.
Probably missing some magic Annotation I don't know.
Thanks, hope my question was well explained for everyone.
Extract Brand as new table/entity(read about database normalization).
And after just do one-to-many relationship with that entities(VendingMachines and Brand). would look like that:
class Brand
...
#ManyToOne
#JoinColumn(name="machine_id")
private VendingMachines machines;
I have a cabinet say "tcabinet" in a repository "trepository".
In this repository there are multiple users however their access is restricted by adding the cabinet IDs to the restricted_folder_ids column in dm_user object.
The user has access to the ACL. But still they can not see tcabinet as their access is restricted. There are thousands of such users.
For these users to see the tcabinet. I'll have to add the object id of tcabinet to restricted_folder_ids column of each user which would definitely be a large task.
Is there any way to make them able to see the cabinet without adding the cabinet id to each user?
As confirmed by OpenText also, there is no other way to achive this. However we can add the cabinet to everyone's 'restricted_folder_id' attribute in dm_user table.
UPDATE dm_user object
APPEND restricted_folder_ids=’<Object ID of the Cabinet>’
WHERE user_name='<user_name>'
NOTE: If you are using this method, make sure to filter out the users which does not have any existing 'restricted_folder_id' in dm_user table, else this method will restrict the access of these users to a single folder which might not be the intention.
Good afternoon everyone!
I'm studying NHibernate, and decided to make some changes. Among them, I noticed that some fields are unnecessary. So I bring my doubt:
I have a list, let's call it Class_List within each study class, I can have N students for each class. Within the list Class_List, I also have other properties as simple as the name of the class.
How I see it is unnecessary to store how many students I have in the database, I would, in a single query, how many records I have. This, using NHibernate.
Is this possible? How?
Best regards,
Gustavo.
Edit: I've forgot to say one thing... I want to return this number of record, as a column. But this column is not mapped in my .hbm.xml file.
If students are mapped as a collection on Class, you can try using something like this:
var numberOfStudents = session.CreateCriteria<Class>()
.Add(Restrictions.IdEq(1))
.CreateCriteria("_students", "students")
.SetProjection(Projections.RowCount())
.UniqueResult<Int32>();
Where '1' is the id of the class (you can use other property) and '_students' is the name of the students collection.
Entities
We have an entity called Product which is loaded using NHibernate.
Product has a category which NHibernate happily populates for me.
Database
In the database, Product has a foreign key for category.
Scenario
User edits this Product (via a web interface) and chooses a different category (say instead of "Fish" we select "Veg").
This is probably a dropdown list, with each category shown. When they choose a different category we get an int key.
Problem
Obviously we now want to save the changes to Product but in effect the only change is to save a new int (say 2, instead of 1).
So we retrieve the existing Product, and now comes the problem.
We don't have a "CategoryID" field on Product, we only have a Category property.
But we don't really want to retrieve the category (by id) just to assign it to the Product.
So I guess what I want to know is should we...
a) Add a CategoryID property to Product
b) Create a new category, assign it the relevant id and attach that to Product (but surely that will cause errors, or overwrite the existing category)
c) Retrieve (lookup) the category from the system (by id) and attach that to the Product
d) Do something else entirely!
It looks like you might be able to using the Session.Load(id) functionality.
Session.Load is a special method that returns a proxy with the ID until you request another property at which point it loads. It throws an error if there is no item matching the ID. Try something like:
product.Category = Session.Load<Category>(2); //2 being the new category ID
Session.SaveOrUpdate(product);
I just did a little testing and it did not seem to pull back the entire Category.
Updated: Session.Load is the correct answer
product.Category = session.Load<Category>(2);
session.Save(product);
Use NH's EnumStringType<T> to map your Category as an enum to the respective database value (which can be a string or a number). You'll find quite a few usage examples, if you google for it.
HTH!
I have a reference/lookup table whose main purpose is to provide the user with a list of existing options. The user will also have the ability to enter new items into the list. How would you map this in NHibernate?
For example, say I have an Address class with a City field. The database has an Address table and a City lookup table. (I can define the relationships however I want at this point.) When editing the address:
The user can select any available City, or can enter a new City.
A new city entered must be added to the lookup table.
Editing an Address instance's city should either change the reference - if the edited city also exists in the DB - or create a new City entry by that name and refer to it. (If I edit "Chicago" to "New York", I don't want all addresses in Chicago to change to New York; just the one I'm looking at.)
I've been scouring NHib docs, and I'm not at all sure what approach I should take.
EDIT:
Part of my issue stems from the fact that I'm trying to avoid creating a "City" class with a single property - I'd just like Address.City to be a string in the domain model. This may be unwise, I don't know.
So you have addresses and you want a distinct list of cities. You'll either need to do the "distinct" operation in your code or in the database. Doing it in code implies a City class mapped onto your City table - I can't see how you can avoid it.
If the "distinct" operation is done it the database, you'll need write sprocs to insert and update an Address. These sprocs would then contain the logic of "use the City if it's in the table, otherwise create a new one".
Personally I'm not in favour of sprocs if they can be avoided and so I'd recommend that you create a City class and map it with a on your Address class.