如何在实体框架连接上更改数据库

Question

我有一个 ADO.NET 实体数据模型，我想在多个数据库（在同一台服务器上）上使用它，您将如何解决它？

// This results in a exception, "Specified method is not supported".
private MyEntities _db = new MyEntities();

public IQueryable<MyObject> GetMyObjects(string database)
{
    _db.Connection.ChangeDatabase(database);

    return _db.MyObjects
}

// This works...
private MyEntities _db;
private string entityConnectionString = ConfigurationManager.ConnectionStrings["MyEntities"].ConnectionString;

public IQueryable<MyObject> GetMyObjects(string database)
{
    _db = new MyEntities(entityConnectionString.Replace("__REPLACE_ME__", database));

    return _db.MyObjects
}

Answer 1

我可能会修改您的“This works...”版本，如下所示::

private MyEntities _db;
private string entityConnectionString = ConfigurationManager.ConnectionStrings["MyEntities"].ConnectionString;

public IQueryable<MyObject> GetMyObjects(string database)
{
    var ecsb = new EntityConnectionStringBuilder(entityConnectionString);
    var scsb = new SqlConnectionStringBuilder(ecsb.ProviderConnectionString)
    scsb.InitialCatalog = database;
    ecsb.ProviderConnectionString = scsb.ToString();
    _db = new MyEntities(ecsb.ToString());    
    return _db.MyObjects
}