CODEWITHSUNDEEP
nhibernatedynamicschema
user134363
user134363

Reputation:

NHibernate - How do I change schemas during run time?

I'm using NHibernate to connect to an ERP database on our DB2 server. We have a test schema and a production schema. Both schemas have the same table structure underneath. For testing, I would like to use the same mapping classes but point NHibernate to the test environment when needed and then back when in production. Please keep in mind that we have many production schemas and each production schema has an equivalent test schema.

I know that my XML mapping file has a schema property inside it, but since it's in XML, it's not like I can change it via a compiler directive or change the schema property based on a config file.

Any ideas?

Thank You.

Upvotes: 1

Views: 4476

Answers (5)

Sheng
Sheng

Reputation: 834

The code to fix HBM XML resources.

    // This is how you get all the hbm resource names.
    private static IList<string> GetAllHbmXmlResourceNames(Assembly assembly)
    {
        var result = new List<string>();

        foreach (var resource in assembly.GetManifestResourceNames())
        {
            if (resource.EndsWith(".hbm.xml"))
            {
                result.Add(resource);
            }
        }

        return result;
    }
    // This is how you get the stream for each resource.
    Assembly.Load(assembly).GetManifestResourceStream(name)
    // What you need to do next is to fix schema name in this stream
    // Replacing schema name.
    private Stream FixSchemaNameInStream(Stream stream)
    {
        StreamReader strStream = new StreamReader(stream);
        string strCfg = strStream.ReadToEnd();
        strCfg = strCfg.Replace(string.Format("schema=\"{0}\"" , originalSchemaName), string.Format("schema=\"{0}\"" , newSchemaName));

        return new MemoryStream(Encoding.ASCII.GetBytes(strCfg));
    }

Upvotes: 1

Sheng
Sheng

Reputation: 834

I have found following link that actually fixes the problem.

How to set database schema for namespace in nhibernate

The sample code could be

cfg.ClassMappings.Where(cm => cm.Table.Schema == "SchemaName")
    .ForEach(cm => cm.Table.Schema = "AnotherSchemaName");

This should happen before you initialize your own data service class.

@Brian, I tried NHibernate.Mapping.Attributes, the attribute value you put inside should be a constant. So it could not be updated during run time. How could you have set the property's value using a parameter value in configuration file?

Upvotes: 1

user134363
user134363

Reputation:

To get what I wanted, I had to use NHibernate.Mapping.Attributes.

[NHibernate.Mapping.Attributes.Class(0, Table = “MyTable”, Schema = MySchemaConfiguration.MySchema)]

In this way, I can create a class like MySchemaConfiguration and have a property inside of it like MySchema. I can either set the property's value via a compiler directive or get it through a configuration file. This way I only have to change the schema in one place and it will be reflected throughout all of the other mappings.

Upvotes: 1

zowens
zowens

Reputation: 1566

Take a look at SchemaUpdate.

http://blogs.hibernatingrhinos.com/nhibernate/archive/2008/04/28/create-and-update-database-schema.aspx

Upvotes: -1

Andriy Volkov
Andriy Volkov

Reputation: 18923

No need to specify schema in the mappings: there's a SessionFactory-level setting called default_schema. However, you can't change it at runtime, as NHibernate pregenerates and/or caches SQL queries, including the schema part.

Upvotes: 1

Related Questions