CreateUpdateDDLScript returns NULL and CreateDDLScript returns ""

[Elisabeth Ohmstead]

Dear Sir or Madam,

I have been experiencing a strange behavior of the ORM. My code is as follows:

private static void UpdateDatabase()

        {

            using (var context = new EntitiesModel())

            {

                var schemaHandler = context.GetSchemaHandler();

                EnsureDB(schemaHandler);

            }

        }

 

        private static void EnsureDB(ISchemaHandler schemaHandler)

        {

            string script = null;

            if (schemaHandler.DatabaseExists())

            {

                script = schemaHandler.CreateUpdateDDLScript(null);

            }

            else

            {

                schemaHandler.CreateDatabase();

                script = schemaHandler.CreateDDLScript();

            }

            if (!string.IsNullOrEmpty(script))

            {

                schemaHandler.ExecuteDDLScript(script);

            }

        }

The line script = schemaHandler.CreateUpdateDDLScript(null); always returns null and script = schemaHandler.CreateDDLScript(); always return an empty string.

I have tried to modify my database and delete it but the strange behavior still persists.
Please help me!

[Yordan]

Hi Elisabeth,

The reason why the method CreateUpdateDDLScript(null) returns null is because your model is up to date with your database and there is nothing to update.Please note that if there is no database with the specified name, the CreateDDLScript and the CreateUpdateDDLScript will not create it but instead they will throw an exception. Should you want to create the database you need to call the method CreateDatabase on the ISchemaHandler interface.
As for the exact definition of the CreateDDLScript and the CreateUpdateDDLScript please have a look into those descriptions:

CreateUpdateDDLScript - generates a migration data definition language (DDL) script. What this basically does is it generates an SQL script that will create only the missing parts based on a comparison between your metadata and your actual database.The method is expect to return null should your model match your database.

CreateDDLScript - generates a data definition language (DDL) script that creates schema objects (tables, primary keys, foreign keys) by using the metadata provided by the OpenAccessContext. This method does not take into consideration your current database state. Also it will return empty string if you don't have any classes in your model (the RLINQ file) with property UpdateSchema set to true.

Should you face any further difficulties please do not hesitate to contact us back.

Regards,
Yordan
the Telerik team

[Dave]

I must be missing something to - because when I run those commands above with a new database in the connectionstring - it errors at

script = handler.CreateUpdateDDLScript(Nothing)

As expected but when it falls to the next segment

Dim throwException As Boolean = False
                Try
                    handler.CreateDatabase()
                    script = handler.CreateDDLScript()
                Catch
                    throwException = True
                End Try
                If throwException Then
                    Throw
                End If

It will create a blank database BUT CreateDDLScript returns an empty string, so it leaves me with an empty database.

Is there something I am missing?

[Yordan]

Hello Dave,

Please ensure that every class that you want a table to be generated for, has the property UpdateSchema set to true. After setting this property to true the method CreateDDLScript should return a non empty string. That returned string should be passed to the method ExecuteDDLScript so the tables are created in the empty database. The complete code for creating the database is similar to the following:

Public Sub UpdateSchema()
Dim handler = Me.GetSchemaHandler()
Dim script As String = Nothing
Try
    script = handler.CreateUpdateDDLScript(Nothing)
Catch
    Dim throwException As Boolean = False
    Try
        handler.CreateDatabase()
        script = handler.CreateDDLScript()
    Catch
        throwException = True
    End Try
    If throwException Then
        Throw
    End If
End Try
If String.IsNullOrEmpty(script) = False Then
    handler.ExecuteDDLScript(script)
End If
End Sub

Please try the suggested approach and if it doesn't work as expected get back to us.
 
Regards,
Yordan
the Telerik team

[Jed]

Good day.

I'd like to ask the same question posted. When I tried to delete my database and then run my program with this code, It did create the database, but not the tables, etc.. What am I missing? What will I do? 

Thanks.

        private static void EnsureDB(ISchemaHandler schemaHandler)
        {
            string script = null;
            if (schemaHandler.DatabaseExists())
            {
                script = schemaHandler.CreateUpdateDDLScript(null);
            }
            else
            {
                schemaHandler.CreateDatabase();
                script = schemaHandler.CreateDDLScript();
            }
            if (!string.IsNullOrEmpty(script))
            {
                schemaHandler.ExecuteDDLScript(script);
            }
        }

[Ady]

Hi Jed,

 Please ensure that for every class that you want a table for, the 'UpdateSchema' property should set to 'true'. You can set this property via the domain model designer by selecting the class,pressing F4 and setting the value in the 'Properties' window.
Once this property is set the 'CreateUpdateDDLScript/CreateDDLScript' methods should generate the required DDL script.

Do let me know if that works and in case you need further assistance.

Regards,
Ady
Telerik