Всъщност имах нужда от решение и за това. Бързо приготвих разтвор, който работи добре. Не намерих много информация за това в Интернет, така че не съм сигурен за „EF 4.1 идва с по-добри инструменти за поддръжка, за да го направи“.
Конкретният пример „Промяна на името на схемата по време на изпълнение – Рамка на обект“ не работи напълно за мен, но с някои незначителни модификации го накарах да работи.
Ето един клас DatabaseUtils, който може да го направи:
internal static class DatabaseUtils
{
/// <summary>
/// Builds the connection string for Entity framework.
/// </summary>
/// <returns></returns>
public static EntityConnection BuildConnection(BuildConnectionParams buildConnectionParams)
{
var sqlBuilder = new SqlConnectionStringBuilder
{
DataSource = buildConnectionParams.ServerName,
InitialCatalog = buildConnectionParams.DatabaseName,
IntegratedSecurity = true
};
var providerString = sqlBuilder.ToString();
var entityBuilder = new EntityConnectionStringBuilder
{
Provider = buildConnectionParams.ProviderName,
ProviderConnectionString = providerString,
Metadata = string.Format(@"res://*/{0}.csdl|
res://*/{0}.ssdl|
res://*/{0}.msl", buildConnectionParams.ModelName)
};
return CreateConnection(buildConnectionParams.SchemaName, entityBuilder, buildConnectionParams.ModelName);
}
/// <summary>
/// Creates the EntityConnection, based on new schema & existing connectionString
/// </summary>
/// <param name="schemaName">Name of the schema.</param>
/// <param name="connectionBuilder"></param>
/// <param name="modelName">Name of the model.</param>
/// <returns></returns>
private static EntityConnection CreateConnection(string schemaName, EntityConnectionStringBuilder connectionBuilder, string modelName)
{
Func<string, Stream> generateStream =
extension => Assembly.GetExecutingAssembly().GetManifestResourceStream(string.Concat(modelName, extension));
Action<IEnumerable<Stream>> disposeCollection = streams =>
{
if (streams == null)
return;
foreach (var stream in streams.Where(stream => stream != null))
stream.Dispose();
};
var conceptualReader = generateStream(".csdl");
var mappingReader = generateStream(".msl");
var storageReader = generateStream(".ssdl");
if (conceptualReader == null || mappingReader == null || storageReader == null)
{
disposeCollection(new[] { conceptualReader, mappingReader, storageReader });
return null;
}
var storageXml = XElement.Load(storageReader);
foreach (var entitySet in storageXml.Descendants())
{
var schemaAttribute = entitySet.Attributes("Schema").FirstOrDefault();
if (schemaAttribute != null)
schemaAttribute.SetValue(schemaName);
}
storageXml.CreateReader();
var workspace = new MetadataWorkspace();
var storageCollection = new StoreItemCollection(new[] { storageXml.CreateReader() });
var conceptualCollection = new EdmItemCollection(new[] { XmlReader.Create(conceptualReader) });
var mappingCollection = new StorageMappingItemCollection(conceptualCollection,
storageCollection,
new[] { XmlReader.Create(mappingReader) });
workspace.RegisterItemCollection(conceptualCollection);
workspace.RegisterItemCollection(storageCollection);
workspace.RegisterItemCollection(mappingCollection);
var connection = DbProviderFactories.GetFactory(connectionBuilder.Provider).CreateConnection();
if (connection == null)
{
disposeCollection(new[] { conceptualReader, mappingReader, storageReader });
return null;
}
connection.ConnectionString = connectionBuilder.ProviderConnectionString;
return new EntityConnection(workspace, connection);
}
}
Употреба:
/// <summary>
/// Initializes a new instance of the <see cref="DynamicAQDContext"/> class.
/// </summary>
public DynamicAQDContext()
{
var entityConnection = DatabaseUtils.BuildConnection(new BuildConnectionParams
{
ProviderName = "System.Data.SqlClient",
ServerName = "localhost\\",
DatabaseName = "",
ModelName = "YOURMODEL",
SchemaName = "SCHEMA"
});
if(entityConnection == null)
throw new Exception("Can't create EntityConnection");
_entities = new LINKEntities(entityConnection);
}
повече информация можете да намерите тук:http:/ /bestplayah.com/entity-framework-dynamic-schema-changes-using-database-first-approach/