방법: StructuralType 결과를 반환하는 쿼리 실행(EntityClient)

이 항목에서는 EntityCommand를 사용하여 엔터티 데이터 모델에 대해 명령을 실행하는 방법 및 EntityDataReader를 사용하여 StructuralType 결과를 검색하는 방법의 예제를 제공합니다. EntityType, RowType 및 ComplexType은 StructuralType에서 파생됩니다.

이 예제의 코드를 실행하려면

1. 프로젝트에 AdventureWorks Sales 모델을 추가하고 Entity Framework를 사용하도록 프로젝트를 구성합니다. 이렇게 하려면 다음 중 하나를 수행합니다.

   • 엔터티 데이터 모델 도구가 설치되어 있는 경우 방법: 엔터티 데이터 모델 마법사 사용(Entity Framework)의 절차를 수행합니다.

   • 그렇지 않으면 방법: Entity Framework 프로젝트 수동 구성 및 방법: 엔터티 데이터 모델 수동 정의(Entity Framework)의 절차를 수행합니다.

2. 응용 프로그램의 코드 페이지에서 다음 using 문(Visual Basic에서는 Imports)을 추가합니다.

   Imports System
   Imports System.Collections.Generic
   Imports System.Collections
   Imports System.Data.Common
   Imports System.Data
   Imports System.Data.SqlClient
   Imports System.Data.EntityClient
   Imports System.Data.Metadata.Edm
   Imports System.IO
   ' Add AdventureWorksModel prepended with the root namespace for the project.
   'Imports ProjectName.AdventureWorksModel
   

   using System;
   using System.Collections.Generic;
   using System.Collections;
   using System.Data.Common;
   using System.Data;
   using System.IO;
   using System.Data.SqlClient;
   using System.Data.EntityClient;
   using AdventureWorksModel;
   using System.Data.Metadata.Edm;
   

예제

코드를 테스트하려면 다음 쿼리를 ExecuteStructuralTypeQuery 함수에 인수로 전달합니다.

"SELECT VALUE Product FROM AdventureWorksEntities.Product AS Product"

위의 쿼리는 EntityType 결과를 반환합니다.

Sub ExecuteStructuralTypeQuery(ByVal esqlQuery As String)
    If (esqlQuery.Length = 0) Then
        Console.WriteLine("The query string is empty.")
        Return
    End If


    Using conn As EntityConnection = New EntityConnection("name=AdventureWorksEntities")
        conn.Open()

        Try
            ' Create an EntityCommand.
            Using cmd As EntityCommand = conn.CreateCommand()
                cmd.CommandText = esqlQuery
                ' Execute the command.
                Using reader As EntityDataReader = cmd.ExecuteReader(CommandBehavior.SequentialAccess)
                    Do While (reader.Read())
                        StructuralTypeVisitRecord(CType(reader, IExtendedDataRecord))
                    Loop
                End Using
            End Using
        Catch ex As Exception
            Console.WriteLine(ex.ToString())
        End Try
        conn.Close()
    End Using
End Sub

Sub StructuralTypeVisitRecord(ByVal record As IExtendedDataRecord)
    Dim fieldCount As Integer
    fieldCount = record.DataRecordInfo.FieldMetadata.Count
    Dim fieldIndex As Integer
    For fieldIndex = 0 To fieldCount - 1
        Console.Write(record.GetName(fieldIndex) + ": ")

        ' If the field is flagged as DbNull, the shape of the value is undetermined.
        ' An attempt to get such a value may trigger an exception.
        If (record.IsDBNull(fieldIndex) = False) Then
            Dim fieldTypeKind As BuiltInTypeKind = record.DataRecordInfo.FieldMetadata(fieldIndex).FieldType.TypeUsage.EdmType.BuiltInTypeKind()
            ' The EntityType, ComplexType and RowType are structural types
            ' that have members. 
            ' Read only the PrimitiveType members of this structural type.
            If (fieldTypeKind = BuiltInTypeKind.PrimitiveType) Then
                ' Primitive types are surfaced as plain objects.
                Console.WriteLine(record.GetValue(fieldIndex).ToString())
            End If
        End If
    Next
End Sub

static void ExecuteStructuralTypeQuery(string esqlQuery)
{
    if (esqlQuery.Length == 0)
    {
        Console.WriteLine("The query string is empty.");
        return;
    }

    using (EntityConnection conn =
        new EntityConnection("name=AdventureWorksEntities"))
    {
        conn.Open();

        try
        {
            // Create an EntityCommand.
            using (EntityCommand cmd = conn.CreateCommand())
            {
                cmd.CommandText = esqlQuery;
                // Execute the command.
                using (EntityDataReader rdr =
                    cmd.ExecuteReader(CommandBehavior.SequentialAccess))
                {
                    // Start reading results.
                    while (rdr.Read())
                    {
                        StructuralTypeVisitRecord(rdr as IExtendedDataRecord);
                    }
                }
            }
        }
        catch (EntityException ex)
        {
            Console.WriteLine(ex.ToString());
        }
        conn.Close();
    }
}

static void StructuralTypeVisitRecord(IExtendedDataRecord record)
{
    int fieldCount = record.DataRecordInfo.FieldMetadata.Count;
    for (int fieldIndex = 0; fieldIndex < fieldCount; fieldIndex++)
    {
        Console.Write(record.GetName(fieldIndex) + ": ");

        // If the field is flagged as DbNull, the shape of the value is undetermined.
        // An attempt to get such a value may trigger an exception.
        if (record.IsDBNull(fieldIndex) == false)
        {
            BuiltInTypeKind fieldTypeKind = record.DataRecordInfo.FieldMetadata[fieldIndex].
                FieldType.TypeUsage.EdmType.BuiltInTypeKind;
            // The EntityType, ComplexType and RowType are structural types
            // that have members. 
            // Read only the PrimitiveType members of this structural type.
            if (fieldTypeKind == BuiltInTypeKind.PrimitiveType)
            {
                // Primitive types are surfaced as plain objects.
                Console.WriteLine(record.GetValue(fieldIndex).ToString());
            }
        }
    }
}

참고 항목

개념

Entity SQL 참조

기타 리소스

EntityClient 사용(Entity Framework 작업)