Question

We are using Castle ActiveRecord as a helper layer on top of NHibernate. To generate our database, we use:

ActiveRecordStarter.CreateSchema();

To generate the sql for building our database we use:

ActiveRecordStarter.GenerateCreationScripts(filename);

They work like a charm. However we sometimes don’t want to generate a table for every one of our entities. I believe nhibernate has a mechanism for excluding certain tables from a schema build (see here) – does anyone know whether ActiveRecord can do the same thing?

Answer 1

For posterity, here’s what I ended up doing:

1) Grabbed the NHibernate SchemaExporter source code and renamed the class to “OurSchemaExporter”.

2) Added a new constructor:

    public OurSchemaExporter(Configuration cfg, Func<string, bool> shouldScriptBeIncluded)
        : this(cfg, cfg.Properties)
    {
        this.shouldScriptBeIncluded = shouldScriptBeIncluded ?? (s => true);
    }

3) Modified the initialize method to call out to find out whether a script should be included:

    private void Initialize()
    {
        if (this.wasInitialized)
            return;
        if (PropertiesHelper.GetString("hbm2ddl.keywords", this.configProperties, "not-defined").ToLowerInvariant() == Hbm2DDLKeyWords.AutoQuote)
            SchemaMetadataUpdater.QuoteTableAndColumns(this.cfg);
        this.dialect = Dialect.GetDialect(this.configProperties);
        this.dropSQL = this.cfg.GenerateDropSchemaScript(this.dialect);
        this.createSQL = this.cfg.GenerateSchemaCreationScript(this.dialect);

        // ** our modification to exclude certain scripts **
        this.dropSQL = new string[0]; // we handle the drops ourselves, as NH doesn't know the names of all our FKs
        this.createSQL = this.createSQL.Where(s => shouldScriptBeIncluded(s)).ToArray();

        this.formatter = (PropertiesHelper.GetBoolean("format_sql", this.configProperties, true) ? FormatStyle.Ddl : FormatStyle.None).Formatter;
        this.wasInitialized = true;
    }

4) When using OurSchemaExporter, check whether we want to include certain tables by looking at the contents of each SQL create script:

var ourSchemaExport = new TpsSchemaExporter(configuration, ShouldScriptBeIncluded);

...

private bool ShouldScriptBeIncluded(string script)
{
  return !tablesToSkip.Any(t => ShouldSkip(script, t));
}

private static bool ShouldSkip(string script, string tableName)
{
  string s = script.ToLower();
  string t = tableName.ToLower();
  return
    s.Contains(string.Format("create table dbo.{0} ", t))
    || s.Contains(string.Format("alter table dbo.{0} ", t))
    || s.EndsWith(string.Format("drop table dbo.{0}", t));
}

A hack, but it does the job.