![](/img/trans.png)
[英]Entity Framework 6 Database First - How to share connection and transaction with ADO
[英]Share connection between DbContext objects in Entity Framework 6 Database first approach
我正在嘗試使用EF 6在2個不同的數據庫上下文對象之間共享連接。 我已經在這里提到的代碼https://msdn.microsoft.com/en-us/data/dn456843.aspx可以用於單個數據庫上下文,但是一旦我嘗試與另一個數據庫上下文對象共享連接,我就是遇到麻煩了。 以下是我這樣做的目的。
public class MyUnitOfWork
{
// BAD CODE : having static connection / transaction is bad design , i use DI to implement this properly without need for static fields , this code is used here to avoid having to mention my DI configuration;
public static EntityConnection _commonConnection ;
public static System.Data.Entity.DbContextTransaction _commonTransaction;
// Generic function to create DBContext object based on T supplied.
public static T GetDbContext<T>()
{
if(_commonConnection == null)
{
// generates a generic connection string
_commonConnection = new EntityConnection(DbContextBase.GenerateConnectionString());
_connection.Open();
_commonTransaction = _connection.BeginTransaction(System.Data.IsolationLevel.Snapshot);
}
T myContextObject = (T)Activator.CreateInstance(typeof(T), new object[1] { _connection });
myContextObject .Database.UseTransaction(_transaction);
return myContextObject;
}
}
連接字符串的生成代碼如下:
string GenerateConnectionString()
{
var entityBuilder = new EntityConnectionStringBuilder
{
Provider = "System.Data.SqlClient",
ProviderConnectionString = SharedDatabase.SQLBase.DBconnection + "multipleactiveresultsets=True;" ,
Metadata = @"res://*/;"
};
return entityBuilder ;
}
然后,可以像這樣從函數的不同位置調用GetDbContext。
GetById(int id)
{
var dbcontext = MyUnitOfWork.GetDbContext<OrdersDbContext>();
return dbcontext.Orders.Where(.......);
}
GetCustomerInfo( int id)
{
var dbcontext = MyUnitOfWork.GetDbContext<CustomerDbContext>();
return dbcontext.Customer.Where(.......);
}
因為我正在使用通用元數據部分,所以在實體框架中出現錯誤“無論名稱空間如何,都不能有多個具有相同名稱的實體”
但是,如果我指定.csdl / .ssdl文件的名稱,則連接(以及事務)將不再常見,我必須為每個DBContext創建一個連接和事務(這是我要避免的事情)
看來我撞到了。 有沒有辦法讓我使用相同的連接而不出現重復的實體錯誤? 將實體名稱更改為其他名稱對我來說不是一個選擇,因為這將是非常耗時的更改,我必須在30多個db上下文/ EDMX文件中進行更改,這會對生產產生巨大影響。
如使用事務(EF6及更高版本)所示,使用以下代碼為您的上下文提供現有事務:
string GenerateConnectionString()
{
return SharedDatabase.SQLBase.DBconnection + "multipleactiveresultsets=True;";
}
public class MyUnitOfWork
{
SqlConnection _commonConnection;
DbTransaction _commonTransaction;
// Generic function to create DBContext object based on T supplied.
public T GetDbContext<T>()
{
if (_commonConnection == null)
{
// generates a generic connection string
_commonConnection = new SqlConnection(DbContextBase.GenerateConnectionString());
_commonConnection.Open();
_commonTransaction = _connection.BeginTransaction(IsolationLevel.Snapshot);
}
MetadataWorkspace workspace = new MetadataWorkspace(
string.Format("res://*/{0}.csdl|res://*/{0}.ssdl|res://*/{0}.msl;", typeof(T).Name).Split('|'),
new Assembly[] { Assembly.GetExecutingAssembly() });
var connection = new EntityConnection(workspace, _commonConnection);
T myContextObject = (T)Activator.CreateInstance(typeof(T), new object[] { connection });
myContextObject.Database.UseTransaction(_commonTransaction);
return myContextObject;
}
}
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.