如何在實體框架連接上更改數據庫

Question

我得到了一個ADO.NET實體數據模型，我想在多個數據庫上使用（在同一臺服務器上），您將如何解決它？

// 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

我可能會修改你的「這個工程......」的版本，像這樣::

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 
}