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在本文中，您将开始创建根据 MVVM 模式构建的示例应用程序，并学习如何使用 Scaffolding Wizard。

获取工具下载 - DevExpress v21.2

1. 创建一个新的WinForms应用程序。 要创建项目的数据模型，请添加一个新的模型文件夹并使用下面的代码片段创建三个类——帐户、交易和类别，这些类使用数据注释属性并要求将 System.ComponentModel.DataAnnotations 库包含在您的项目中。

账户数据模型

C#

using System.ComponentModel.DataAnnotations;
namespace MVVMExpenses.DataModels {
public class Account {
[Key, Display(AutoGenerateField = false)]
public long ID { get; set; }
[Required, StringLength(30, MinimumLength = 4)]
[Display(Name = "ACCOUNT")]
public string Name { get; set; }
[DataType(DataType.Currency)]
[Display(Name = "AMOUNT")]
public decimal Amount { get; set; }
public override string ToString() {
return Name + " (" + Amount.ToString("C") + ")";
}
public virtual ICollection<Transaction> Transactions { get; set; }
}
}

VB.NET

Imports System.ComponentModel.DataAnnotations
Namespace MVVMExpenses.DataModels
Public Class Account
<Key, Display(AutoGenerateField := False)>
Public Property ID() As Long
<Required, StringLength(30, MinimumLength := 4), Display(Name := "ACCOUNT")>
Public Property Name() As String
<DataType(DataType.Currency), Display(Name := "AMOUNT")>
Public Property Amount() As Decimal
Public Overrides Function ToString() As String
Return Name & " (" & Amount.ToString("C") & ")"
End Function
Public Overridable Property Transactions() As ICollection(Of Transaction)
End Class
End Namespace

类别数据模型

C#

using System.ComponentModel.DataAnnotations;
namespace MVVMExpenses.DataModels {
public class Category {
[Key, Display(AutoGenerateField = false)]
public long ID { get; set; }
[Required, StringLength(30, MinimumLength = 5)]
[Display(Name = "CATEGORY")]
public string Name { get; set; }
[EnumDataType(typeof(TransactionType))]
[Display(Name = "TRANSACTION TYPE")]
public TransactionType Type { get; set; }
public override string ToString() {
return Name + " (" + Type.ToString() + ")";
}
public virtual ICollection<Transaction> Transactions { get; set; }
}
}

VB.NET

Namespace MVVMExpenses.DataModels
Public Class Category
<Key, Display(AutoGenerateField := False)>
Public Property ID() As Long
<Required, StringLength(30, MinimumLength := 5), Display(Name := "CATEGORY")>
Public Property Name() As String
<EnumDataType(GetType(TransactionType)), Display(Name := "TRANSACTION TYPE")>
Public Property Type() As TransactionType
Public Overrides Function ToString() As String
Return Name & " (" & Type.ToString() & ")"
End Function
Public Overridable Property Transactions() As ICollection(Of Transaction)
End Class
End Namespace

交易数据模型

C#

using System.ComponentModel.DataAnnotations;
namespace MVVMExpenses.DataModels {
public enum TransactionType {
Expense,
Income
}
public class Transaction {
[Key, Display(AutoGenerateField = false)]
public long ID { get; set; }
[Display(AutoGenerateField = false)]
public long AccountID { get; set; }
[Display(Name = "ACCOUNT")]
public virtual Account Account { get; set; }
[Display(AutoGenerateField = false)]
public long CategoryID { get; set; }
[Display(Name = "CATEGORY")]
public virtual Category Category { get; set; }
[DataType(DataType.Date)]
[Display(Name = "DATE")]
public DateTime Date { get; set; }
[DataType(DataType.Currency)]
[Display(Name = "AMOUNT")]
public decimal Amount { get; set; }
[DataType(DataType.MultilineText)]
[Display(Name = "COMMENT")]
public string Comment { get; set; }
}
}

VB.NET

Namespace MVVMExpenses.DataModels
Public Enum TransactionType
Expense
Income
End Enum
Public Class Transaction
<Key, Display(AutoGenerateField := False)>
Public Property ID() As Long
<Display(AutoGenerateField := False)>
Public Property AccountID() As Long
<Display(Name := "ACCOUNT")>
Public Overridable Property Account() As Account
<Display(AutoGenerateField := False)>
Public Property CategoryID() As Long
<Display(Name := "CATEGORY")>
Public Overridable Property Category() As Category
<DataType(DataType.Date), Display(Name := "DATE")>
Public Property [Date]() As Date
<DataType(DataType.Currency), Display(Name := "AMOUNT")>
Public Property Amount() As Decimal
<DataType(DataType.MultilineText), Display(Name := "COMMENT")>
Public Property Comment() As String
End Class
End Namespace

2. 跳转到Visual Studio 的 Project 菜单并选择 Manage NuGet Packages...菜单项，在在线存储中搜索 Entity Framework 6 package，然后单击 ‘Install’，请注意如果未安装此 NuGet 包，您将无法在此示例应用程序中使用实体模型。

3. 添加以下 DbContext 类后代，它将用作 DevExpress Scaffolding Wizard 的上下文。

C#

using System.Data.Entity;
using MVVMExpenses.DataModels;

namespace MVVMExpenses.DataBase {
public class MyDbContext : System.Data.Entity.DbContext {
static MyDbContext() {
System.Data.Entity.Database.SetInitializer<MyDbContext>(null);
}
public DbSet<Account> Accounts { get; set; }
public DbSet<Category> Categories { get; set; }
public DbSet<Transaction> Transactions { get; set; }
}
}

VB.NET

Imports System.Data.Entity
Imports MVVMExpenses.DataModels

Namespace MVVMExpenses.DataBase
Public Class MyDbContext
Inherits System.Data.Entity.DbContext

Shared Sub New()
System.Data.Entity.Database.SetInitializer(Of MyDbContext)(Nothing)
End Sub
Public Property Accounts() As DbSet(Of Account)
Public Property Categories() As DbSet(Of Category)
Public Property Transactions() As DbSet(Of Transaction)
End Class
End Namespace

4. 在继续下一步之前，构建您的项目并确保它编译时没有错误。 然后，在 Visual Studio 解决方案资源管理器中右键单击您的项目并选择 Add DevExpress Item - Data Model Scaffolding...（参见下图）。 这将启动 Scaffolding Wizard，它将生成完整的应用程序层次结构，包括来自数据上下文的 MVVM-ready DataModel。

注意：如果缺少此菜单项，请右键单击您的项目并选择默认的 Visual Studio Add - New Item... 选项。 在对话框中，选择 DevExpress Template Gallery 并手动启动 Scaffolding Wizard - 选择 Data Model Scaffolding 选项卡（WinForms Data Models 组）并单击右下角的 Run Wizard 按钮。

在 Wizard 对话框中，选择在第二步中创建的上下文，然后单击 Next。 检查所有必需的表和视图，然后单击Finish来启动模型生成。

5. 结果，您将看到许多新文件、文件夹和类添加到您的应用程序中。

目前，只有向导生成的两个文件夹值得一提 - 包含您的 CRUD 数据模型的 DataModel 文件夹和包含 DbContext 中每个表的 MVVM ViewModel 的 ViewModels 文件夹 - Account、Category 和 Transaction。 在接下来的课程中，您将学习如何为这些 ViewModel 创建 View。

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