Generate Database From Attributes or XML

alsilk · **Joined:** Wed Oct 12, 2005 4:36 am **Posts:** 9

I am new to nHibernate but I have been using an ORM that generated the database tables for me,,

Is there a tool that can generate the database tables and relations from the xml or the attributes ??

Thanks

KPixel · **Posted:** Wed Oct 12, 2005 1:37 pm

Yes, SchemaExport:

Code:

NHibernate.Cfg.Configuration cfg = GetFullyConfigured(...);
new NHibernate.Tool.hbm2ddl.SchemaExport(cfg).Create(true, true);

alsilk · **Joined:** Wed Oct 12, 2005 4:36 am **Posts:** 9

Thanks for the reply,

But is it possible to use that at runtime ?
That the user can specify the database connection details, then the database is generated and then used without having to restart the application to reload a configuration file ?

I am asking that because I will be using nHibernate in a desktop application , and the user might specify the connection settings, so i wanted to use these settings without asking him to change them in a config file or reload the application to reload that file ,,..

Regards

KPixel · **Posted:** Thu Oct 13, 2005 9:33 am

Yes, it works at runtime.

alsilk · **Joined:** Wed Oct 12, 2005 4:36 am **Posts:** 9

Hello again,
I have tried

Code:

NHibernate.Cfg.Configuration cfg = GetFullyConfigured(...); 
new NHibernate.Tool.hbm2ddl.SchemaExport(cfg).Create(true, true);

on a sample i downloaded from [url=http://weblogs.asp.net/pwilson/archive/2005/05/26/409042.aspx] wilson sample
[/url]

its hbm.xml file contains many-to-many relation as the following [i trimmed some fields for simplicity]

Code:

<class name="Wilson.NHibernate.Example.Category, WilsonNHibernateExample" table="Categories">
      <id name="Id" column="CategoryId">
         <generator class="assigned" />
      </id>
      <bag name="Contacts" table="CategoryContacts" cascade="none" access="nosetter.camelcase" lazy="false" inverse="true">
         <key column="CategoryId" />
         <many-to-many column="ContactID" class="Wilson.NHibernate.Example.Contact, WilsonNHibernateExample" />
      </bag>
   </class>
   <class name="Wilson.NHibernate.Example.Contact, WilsonNHibernateExample" table="Contacts" discriminator-value="?" >
      <id name="Id" column="ContactId" access="nosetter.camelcase" unsaved-value="0">
         <generator class="identity" />
      </id>
      <bag name="Categories" table="CategoryContacts" cascade="none" access="nosetter.camelcase" lazy="false" inverse="false">
         <key column="ContactId" />
         <many-to-many column="CategoryId" class="Wilson.NHibernate.Example.Category, WilsonNHibernateExample" />
      </bag>
   </class>

This xml generates

Code:

create table CategoryContacts (
  CategoryId NVARCHAR(255) not null,
   ContactID INT null,
   ContactId INT not null
)

which causes an error clearly because of the duplicate column name.
This is caused that the column is generated twice from both the decalaratins in the two classes ,,
how to overcome this error ?
or what am i missing ?

sergey · **Posted:** Wed Oct 26, 2005 8:11 am

I think that if you correct the case of ContactID to ContactId everything will work as expected.

alsilk · **Joined:** Wed Oct 12, 2005 4:36 am **Posts:** 9

OK ,, That hurts 8) ,, it did work

Thanks alot

alsilk · **Joined:** Wed Oct 12, 2005 4:36 am **Posts:** 9

Is there a way to generate default mapping xml file ?
I need a tool to parse the code files (classes) generate a default mapping xml file , for native data types fields at least and then i ll handle relations between objects,

Is there a tool that do that without adding attributes to all fields ???

KPixel · **Posted:** Thu Oct 27, 2005 8:47 am

Without attributes, there is no way to give all the information required to build a mapping file... You might take all public properties and only set their name in the mapping, but it will not be time-saving in the long run.

Anyway, you can easily write a generator using reflection to do this job...

alsilk · **Joined:** Wed Oct 12, 2005 4:36 am **Posts:** 9

I thought of writing my own parser but the reflection Idea is better :idea: ,

Thanks for your help