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[news.eclipse.technology.dali] Re: Dali Galileo - Entities and properties naming stragety

Marc,

there are probably a couple of issues here.

Dali treats MySQL as a case-sensitive database. This is because MySQL is a bit whacked when it comes to case-sensitivity (e.g. the case-sensitivity of table names depends on the case-sensitivity of the underlying O/S file system). As a result, Dali takes the conservative approach of validating the various database objects with case-sensitive identifiers. So, to continue with your example, if your Java field name is "name" then the MySQL column must also be named "name" (not "Name" or "NAME"). If the names do not match, Dali will generate a validation error.

The other issue is that Dali actually "out-sources" the creation of tables to your JPA runtime library. (Part of our effort to integrate with the rest of the Eclipse ecosystem. :-) ) Since we ship with EclipseLink, I'm guessing you have configured your JPA project to use EclipseLink. If that is the case, when you execute "JPA Tools -> Generate Tables from Entities" Dali is delegating to the EclipseLink runtime library to do the actual work. If the output is problematic for you, you might want to take it up with the EclipseLink project.

As to how we "should" be treating case-sensitivity: the JPA 1.0 spec does not address case-sensitivity at all. The many examples in the spec imply case-*in*sensitivity; but the actual behavior is going to be dependent on your JPA runtime implementation and database server. Dali has attempted to deal with this in as helpful a way as possible (e.g. ignoring or respecting case depending on your target database server). Maybe unfortunately in this case, Dali's interaction with MySQL is case-sensitive. You might try PosgreSQL? :-)

Brian

Marc Schlegel wrote:
Thanks for your answer Brian


your problem is not completely clear. Is this related to Dali Entity
Generation?
Or DDL Generation? What database platform are you using?

Well, I use the contextmenu on the project "JPA Tools -> Generate Tables from Entites" and I am using a local MySql.

Re: the examples you give:

- The 'name' field might not resolve to a column if you are using a
case-sensitive database (e.g. MS SQL Server) and the case does not
match. In your example the field name is "name" while you indicate the
database column name is "Name" - the case of these identifiers does not
match.

As mentioned above, I use MySql. The explanation makes sense, but why is the column then not creates as "name" rather than "NAME" by default? Most of the databases I've seen usually use uppercase table-, columnnames, so why is this not recognized by default (or is this a jpa thing)? Every additional annotation makes my code less readable (I know that JPA adds the @Basic for every field automatically)

Dont get me wrong, the work Jpa and Dali are doing is awesome and I know that a
lot of effort is necessary for this and maybe this has been already addressed
for later releases.

regards
Marc

- The 'customer' field has a validation error because if you do not
specify otherwise, Dali calculates the JPA spec-defined default column
name and looks for it on your database. The validation error indicates
the column is not found and tells you what the calculated default name is.

Brian


Marc Schlegel wrote:
Hello Everyone

I was just about to write about a similar issue, so I think I just
attach it
here (hope that right).

The Dali validation always claims that it cannot resolve the column to
my fields.

Example
@Entity
public class Person extends EntityBase {
private string name;
...
}


It will not be able to resolve the table-column NAME which is created
by dali.
To get this to work I have to name the column directly

@Entity
public class Person extends EntityBase {
@Column(name = "Name")
private string name;
...
}


then recreate the schema and then this works.

It gets a little bit worse for @ManyToOne. For example
    @OneToMany(mappedBy = "customer")
    private List<BankAccount> accounts = new ArrayList<BankAccount>();
works, but the bidirectional mapping
    @ManyToOne
    private Customer customer;
claims "customer_Id" cannot be resolved.

I was googling this quite a bit because I thought the mistake is on my
side, but
all tutorials I've found use the above code (no attributeoverride or
something
like that).

Thanks


Lionel,

This appears to be an unfortunate regression in Entity Generation for
Galileo.  I have entered bug 285032* for this issue and targeted the fix
for the first Galileo maintenance release.  Thanks for bringing this to
our attention.

I can't think of a good workaround for this issue.  You may want to
generate your entities in a previous version of Dali and import them
into your current workspace.

Neil


* https://bugs.eclipse.org/bugs/show_bug.cgi?id=285032



Lionel wrote:

Hello,
Is it possible to configure Dali's naming strategy with Galileo ?
The new naming strategy uses the name of the table "as is" instead of
using
java naming conventions.
If the table is named "user_group" the generated entity is named
User_group.java instead of UserGroup.java as it was with Ganymede.
Is it possible to change this behaviour instead of renaming manually
all entities and all fields (which is not humanly possible) ?
Thanks