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界面控件DevExpress WinForms MVVM使用教程（一）：創(chuàng)建向?qū)?/h2>

翻譯|使用教程|編輯：龔雪|2022-03-02 10:23:36.157|閱讀 302 次

概述：本系列內(nèi)容將開始根據(jù)DevExpress WinForms MVVM創(chuàng)建示例應(yīng)用程序，并學(xué)習(xí)如何使用 Scaffolding Wizard。

相關(guān)鏈接：

在本文中，您將開始創(chuàng)建根據(jù) MVVM 模式構(gòu)建的示例應(yīng)用程序，并學(xué)習(xí)如何使用 Scaffolding Wizard。

1. 創(chuàng)建一個(gè)新的WinForms應(yīng)用程序。要?jiǎng)?chuàng)建項(xiàng)目的數(shù)據(jù)模型，請(qǐng)?zhí)砑右粋€(gè)新的模型文件夾并使用下面的代碼片段創(chuàng)建三個(gè)類——帳戶、交易和類別，這些類使用數(shù)據(jù)注釋屬性并要求將 System.ComponentModel.DataAnnotations 庫(kù)包含在您的項(xiàng)目中。

賬戶數(shù)據(jù)模型

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

類別數(shù)據(jù)模型

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

交易數(shù)據(jù)模型

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. 跳轉(zhuǎn)到Visual Studio 的 Project 菜單并選擇 Manage NuGet Packages...菜單項(xiàng)，在在線存儲(chǔ)中搜索 Entity Framework 6 package，然后單擊 ‘Install’，請(qǐng)注意如果未安裝此 NuGet 包，您將無(wú)法在此示例應(yīng)用程序中使用實(shí)體模型。

3. 添加以下 DbContext 類后代，它將用作 DevExpress Scaffolding Wizard 的上下文。

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. 在繼續(xù)下一步之前，構(gòu)建您的項(xiàng)目并確保它編譯時(shí)沒(méi)有錯(cuò)誤。然后，在 Visual Studio 解決方案資源管理器中右鍵單擊您的項(xiàng)目并選擇 Add DevExpress Item - Data Model Scaffolding...（參見下圖）。這將啟動(dòng) Scaffolding Wizard，它將生成完整的應(yīng)用程序?qū)哟谓Y(jié)構(gòu)，包括來(lái)自數(shù)據(jù)上下文的 MVVM-ready DataModel。

界面控件DevExpress WinForms MVVM使用教程（一）：創(chuàng)建向?qū)? class=

注意：如果缺少此菜單項(xiàng)，請(qǐng)右鍵單擊您的項(xiàng)目并選擇默認(rèn)的 Visual Studio Add - New Item... 選項(xiàng)。在對(duì)話框中，選擇 DevExpress Template Gallery 并手動(dòng)啟動(dòng) Scaffolding Wizard - 選擇 Data Model Scaffolding 選項(xiàng)卡（WinForms Data Models 組）并單擊右下角的 Run Wizard 按鈕。

在 Wizard 對(duì)話框中，選擇在第二步中創(chuàng)建的上下文，然后單擊 Next。檢查所有必需的表和視圖，然后單擊Finish來(lái)啟動(dòng)模型生成。

5. 結(jié)果，您將看到許多新文件、文件夾和類添加到您的應(yīng)用程序中。

目前，只有向?qū)傻膬蓚€(gè)文件夾值得一提 - 包含您的 CRUD 數(shù)據(jù)模型的 DataModel 文件夾和包含 DbContext 中每個(gè)表的 MVVM ViewModel 的 ViewModels 文件夾 - Account、Category 和 Transaction。在接下來(lái)的課程中，您將學(xué)習(xí)如何為這些 ViewModel 創(chuàng)建 View。

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