ASP.Net Linq to Entities：無法加載指定的元數據資源.- EntityConnectionStringBuilder

Question

我已閱讀了相當多的帖子，但這看起來非常有用，但我不確定我瞭解如何實現此解決方案。我是否應該將這些代碼放在使用實體模型的每個類中？我已經閱讀了微軟的文檔，我想我對這個太新了。

我的實體模型是在我的DATALAYER這是一個單獨的項目。我也有BUSINESSLOGIC和UI圖層。從我已經能夠收集到的信息來看，這聽起來像是這個問題與我的實體模型處於不同的項目中有關。是對的嗎？提前致謝！

從另一個帖子一種更好的方式來構建連接字符串是EntityConnectionStringBuilder：

public static string GetSqlCeConnectionString(string fileName) 
{ 
    var csBuilder = new EntityConnectionStringBuilder(); 

    csBuilder.Provider = "System.Data.SqlServerCe.3.5"; 
    csBuilder.ProviderConnectionString = string.Format("Data Source={0};", fileName); 

    csBuilder.Metadata = string.Format("res://{0}/YourEdmxFileName.csdl|res://{0}/YourEdmxFileName.ssdl|res://{0}/YourEdmxFileName.msl", 
     typeof(YourObjectContextType).Assembly.FullName); 

    return csBuilder.ToString(); 
} 

public static string GetSqlConnectionString(string serverName, string databaseName) 
{ 
    SqlConnectionStringBuilder providerCs = new SqlConnectionStringBuilder(); 

    providerCs.DataSource = serverName; 
    providerCs.InitialCatalog = databaseName; 
    providerCs.IntegratedSecurity = true; 

    var csBuilder = new EntityConnectionStringBuilder(); 

    csBuilder.Provider = "System.Data.SqlClient"; 
    csBuilder.ProviderConnectionString = providerCs.ToString(); 

    csBuilder.Metadata = string.Format("res://{0}/YourEdmxFileName.csdl|res://{0}/YourEdmxFileName.ssdl|res://{0}/YourEdmxFileName.msl", 
     typeof(YourObjectContextType).Assembly.FullName); 

    return csBuilder.ToString(); 
} 

Answer 1

你能移動連接的詳細信息到您的配置文件？這裏有一篇關於connection strings的文章。並按照同樣的例子在文章中，這裏是上下文的初始化和使用：

using (EntityConnection connection = EntityConnection("name=AdventureWorksEntities")) 
{ 
    AdventureWorksEntities context = new AdventureWorksEntities(connection); 
    context.AddObject("Customer", customer); 
    context.SaveChanges(); 
} 

編輯：有沒有必要重複連接建築規範在給客戶打電話。你應該遠離呼叫者隱藏這些細節。下面是返回新對象上下文的工廠示例：

//app.config 
<connectionStrings> 
    <add name="TestEntities" connectionString="...." /> 
</connectionStrings> 

//data entities 
public partial class TestEntities : ObjectContext 
{ 
    public TestEntities() : base("name=TestEntities", "TestEntities") 
    { 
     ... 
    } 
    .... 
} 

//factory in Data Access layer 
public sealed class TestEntitiesFactory 
{ 
    public static Func<TestEntities> GetNewTestEntitiesInstance { get; set; } 

    static TestEntitiesFactory() 
    { 
     GetNewTestEntitiesInstance = TestEntitiesCreator.CreateTestEntities; 
    } 
} 

public sealed class TestEntitiesDefaultCreator 
{ 
    public static TestEntities CreateTestEntities() 
    { 
     TestEntities test = new TestEntities(); 

     //whatever initializations you need 

     return test; 
    } 
} 

//business layer 
using (TestEntities ctx = TestEntitiesFactory.GetNewTestEntitiesInstance()) 
{ 

}