進階中繼資料工作空間
本主題將說明 MetadataWorkspace 類別 (Class) 的進階用法，以擷取 Entity Data Model (EDM) 內的中繼資料資訊。為了要進行這項處理，您必須先建立 MetadataWorkspace 類別的新執行個體。然後，您必須向該中繼資料工作空間註冊項目集合。
項目集合會負責載入中繼資料，並透過中繼資料工作空間來使用該中繼資料。如需項目集合的詳細資訊，請參閱項目集合 (中繼資料)。
System.Data.Metadata.Edm 命名空間提供了 RegisterItemCollection 方法，可向中繼資料工作空間註冊項目集合。
RegisterItemCollection 方法會確定每一個模型只註冊單一個項目集合。每一個項目集合都要負責載入有關特定模型的中繼資料。如需使用 ADO.NET 實體架構 之一般應用程式中模型的詳細資訊，請參閱 中繼資料工作空間概觀。
本文件的程式碼範例會建立 MetadataWorkspace 類別的新執行個體 (Instance)。接下來，此程式碼範例會建立及註冊 EdmItemCollection 類別的新執行個體來載入有關概念 (.csdl) 模型的中繼資料，並建立及註冊 StoreItemCollection 類別的新執行個體來載入有關儲存 (.ssdl) 模型的中繼資料。
然後，此程式碼範例會示範如何使用中繼資料工作空間，以擷取有關指定之模型內所有型別的資訊。請注意，中繼資料工作空間是一個執行階段服務元件，它會提供用來擷取中繼資料的支援。
此程式碼範例會使用 CSpace 和 SSpace 指定模型。CSpace 代表概念模型的預設名稱。SSpace 代表儲存體模型的預設名稱。
若要執行以下程式碼範例，您的資料夾必須包含概念 (.csdl)、儲存 (.ssdl) 和對應 (.msl) 結構描述檔案。您也必須使用對應結構描述檔案的名稱來設定 FileName 輸入參數。此範例會使用 AdventureWorks 完整模型 (EDM) 中所定義的 AdventureWorks 模型。
using System;
using System.Data;
using System.Data.SqlClient;
using System.Collections.ObjectModel;
using System.Data.Metadata.Edm;
class AdvancedGetTypeExample
{
// The data folder contains the EDM schemas such as
// conceptual schema file (.csdl),
// the storage schema file (.ssdl),
// and the mapping file (.msl).
private const string
PathToDataFolder = @"..\..\..\..\Adventureworks\Adventureworks";
private const string
ConnectionString = @"server=serverName;database=Adventureworks;Integrated Security=true";
static void Main()
{
try
{
// Construct a new instance of the metadata workspace.
MetadataWorkspace workspace = new MetadataWorkspace();
// Create a new item collection with the specified
// connection and the folder info
// where the entity data model (EDM) schemas exist.
EdmItemCollection edmCollection =
new EdmItemCollection(PathToDataFolder);
// Register the item collection with the metadata workspace.
workspace.RegisterItemCollection(edmCollection);
// Create a new item collection with the specified
// connection and the folder info
// where the entity data model (EDM) schemas exist.
// SqlConnection object is used to supply the types to
// the StoreItemCollection.
StoreItemCollection storeCollection =
new StoreItemCollection(PathToDataFolder);
// Register the item collection with the metadata workspace.
workspace.RegisterItemCollection(storeCollection);
// Get items from the conceptual model.
GetItemsFromModel(workspace, DataSpace.CSpace);
// Get items from the storage model.
GetItemsFromModel(workspace, DataSpace.SSpace);
}
catch (MetadataException exceptionMetadata)
{
Console.WriteLine("MetadataException: {0}",
exceptionMetadata.Message);
}
catch (System.Data.MappingException exceptionMapping)
{
Console.WriteLine("MappingException: {0}",
exceptionMapping.Message);
}
}
public static void GetItemsFromModel
(MetadataWorkspace workspace, DataSpace model)
{
Console.WriteLine("Display items at the {0} model",
model.ToString());
// An EdmType class is the base class for the classes that
// represent types in the Entity Data Model (EDM).
ReadOnlyCollection<EdmType> types =
workspace.GetItems<EdmType>(model);
// For the conceptual model (DataSpace.CSpace):
// This collection contains all types defined in .csdl file and
// also
// the canonical functions and primitive types defined
// in the Entity Data Model (EDM).
// For the storage model (DataSpace.SSpace):
// This collection contains all types defined in .ssdl file
// and also
// all SQL Server primitive types and functions.
// Iterate through the collection to get each type.
foreach (EdmType item in types)
{
Console.WriteLine("Type: {0}, Type in Model: {1} ",
item.GetType().FullName, item.FullName);
}
}
}
Imports System
Imports System.Data
Imports System.Data.SqlClient
Imports System.Collections.ObjectModel
Imports System.Data.Metadata.Edm
Class AdvancedGetTypeExample
' The data folder contains the EDM schemas such as
' conceptual schema file (.csdl),
' the storage schema file (.ssdl),
' and the mapping file (.msl).
Private Const PathToDataFolder As String = _
"..\..\..\..\Adventureworks\Adventureworks"
Private Const ConnectionString As String = _
"server=serverName;database=Adventureworks;Integrated Security=true"
Public Shared Sub Main()
Try
' Construct a new instance of the metadata workspace.
Dim workspace As MetadataWorkspace = New MetadataWorkspace()
' Create a new item collection with the specified
' connection and the folder info
' where the entity data model (EDM) schemas exist.
Dim edmCollection As New EdmItemCollection(PathToDataFolder)
' Register the item collection with the metadata workspace.
workspace.RegisterItemCollection(edmCollection)
' Create a new item collection with the specified
' connection and the folder info
' where the entity data model (EDM) schemas exist.
' SqlConnection object is used to supply the types to
' the StoreItemCollection.
Dim storeCollection As New StoreItemCollection(PathToDataFolder)
' Register the item collection with the metadata workspace.
workspace.RegisterItemCollection(storeCollection)
' Get items from the conceptual model.
GetItemsFromModel(workspace, DataSpace.CSpace)
' Get items from the storage model.
GetItemsFromModel(workspace, DataSpace.SSpace)
Catch exceptionMetadata As MetadataException
Console.WriteLine("MetadataException: {0}", _
exceptionMetadata.Message)
Catch exceptionMapping As MappingException
Console.WriteLine("MappingException: {0}", _
exceptionMapping.Message)
End Try
End Sub
Public Shared Sub GetItemsFromModel( _
ByVal workspace As MetadataWorkspace, _
ByVal model As DataSpace)
Console.WriteLine("Display items at the {0} model", model.ToString)
' An EdmType class is the base class for the classes that
' represent types in the Entity Data Model (EDM).
Dim types As ReadOnlyCollection(Of EdmType) = _
workspace.GetItems(Of EdmType)(model)
' For the conceptual model (DataSpace.CSpace):
' This collection contains all types defined in .csdl file and also
' the canonical functions and primitive types defined
' in the Entity Data Model (EDM).
' For the storage model (DataSpace.SSpace):
' This collection contains all types defined in .ssdl file and also
' all SQL Server primitive types and functions.
' Iterate through the collection to get each type.
Dim item As EdmType
For Each item In types
Console.WriteLine( _
"Type: {0}, Type in Model: {1} ", _
item.GetType.FullName, item.FullName)
Next
End Sub
End Class