I'm looking for the best solution to store Java EE application's global data using Hibernate. It will consist of key value pairs. Example:
projectStarted = "10-11-11"
developerNumber = 3
teamLeader = "John"
As you see, all of this entries have different types.
For now I see two options:
1) Create GlobalData entity. Each field of it will be represented as unique column in the table and will contain unique setting. This way I have no problems with type casting, but I would like to avoid it in case where there will be big amount of settings.
2) Create Setting entity. Each of it will contain two fields: key(Primary key) and value and will be represented as unique record in the table. This is preferable solution, but It's seems to me that I will get a lot of type casting, because settings can be any type.
So basically, I'm looking for the way to implement second solution without getting a lot of troubles from different types. Can anybody help me?
Thanks.
Edit 1.
Yea开发者_运维问答h, thanks Christian. Just got similar idea.
What if I will have Settings entity, which will be like:
@Entity
@Table(name = "settings")
public class Setting {
@Column
private String key;
@Column
private String value;
@Column
private String converterClassFullName; //example by.lugovsky.MyConverter
//Getters, setters
}
And GlobalData class.
public class GlobalData {
private Date projectStarted;
private int developerNumber;
private String teamLeader;
Set<Setting> settings;
//Getters and setters for all, except settings.
}
So basically my idea is to convert Setting entity before persisting/updating/ etc. I can do this in my DAO, but I was wondering, if I could annotate GlobalData class with @Entity annotation as well without creating new table. This way I can set OneToMany annotation to Setting's set and Perform conversions in the internal @PrePersist etc. methods.
Will Hibernate allow me to do this?
Thanks again
You could store a Converter-Class into the db and the let it run through the given converter for a property before using the value. JSF offers Converter API:
public interface Converter{
public Object getAsObject(FacesContext fc, UIComponent component, String value) throws ConverterException;
public String getAsString(FacesContext fc, UIComponent component, Object obj) throws ConverterException;
}
If you have a schema with
name: String
value: String
converter: Class
then you could do something like this:
PropertyEntry pe = // Get from OR-Mapper
Converter c = (Converter) pe.getConverter().newInstance();
Object o = c.getAsObject(null, null, pe.getValue());
// use the object o instead of value
For even more coolness you could also define a field in the class which will not be persisted which you could use to hold the converted value within the object.
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