标签：WebApi DelegateCommand return string int private Prism WPF public
最近通过WPF开发项目，为了对WPF知识点进行总结，所以利用业余时间，开发一个学生信息管理系统【Student Information Management System】。前两篇文章进行了框架搭建和模块划分，以及后台WebApi接口编写，本文在前两篇基础之上，继续深入开发学生信息管理系统的课程管理模块，通过本篇文章，将了解如何进行数据的CRUD操作，将前后端贯穿起来开发。本文仅供学习分享使用，如有不足之处，还请指正。
涉及知识点
在本篇文章中，虽然只介绍一个模块的开发，但是麻雀虽小，五脏俱全，而且掌握一个模块的开发方法，相当于掌握通用的开发方法，就可以举一反三，其他模块的开发也可以水到渠成。涉及到的知识点如下：
- WPF开发中TextBlock，TextBox，DataGrid，Combox等控件的基础使用以及数据绑定等操作。
- MAH样式的使用，在本示例中MAH主要用于统一页面风格，提高用户体验。
- WebApi接口开发，本示例中，WebApi提供接口共客户端使用。
- HttpClient使用，主要用于访问服务端提供的接口。
数据访问流程
一般情况下，交付给客户的都是可视化的操作页面，而不是一些只有专业开发人员才能看懂的WebApi接口。为了更好的描述数据访问流程，以具体代码模块为例，如下所示：
数据操作上下文DataContext
关于WebApi和数据库的相关操作，在上一篇文章中已有说明，本文不再赘述，主要侧重于业务代码。关于课程管理模块的数据操作上下文，有两点需要加以说明：
- DbContext 是EntityFramwork提供的用于访问数据库中数据表的类，一个DbContext实例表示一个session，可用于查询或保存数据实体对应数据表。
- DbSet表示一个对具体数据表中数据的操作映射，如增加，删除，修改，查询等，都是可通过DbSet类型完成。
关于DataContext具体代码，如下所示：
1 namespace SIMS.WebApi.Data
2 {
3 public class DataContext:DbContext
4 {
5 public DbSet<UserEntity> Users { get; set; }
6
7 public DbSet<MenuEntity> Menus { get; set; }
8
9 public DbSet<RoleEntity> Roles { get; set; }
10
11 public DbSet<UserRoleEntity> UserRoles { get; set; }
12
13 public DbSet<RoleMenuEntity> RoleMenus { get; set; }
14
15 /// <summary>
16 /// 学生
17 /// </summary>
18 public DbSet<StudentEntity> Students { get; set; }
19
20 /// <summary>
21 /// 班级
22 /// </summary>
23 public DbSet<ClassesEntity> Classes { get; set; }
24
25 /// <summary>
26 /// 课程
27 /// </summary>
28 public DbSet<CourseEntity> Courses { get; set; }
29
30 /// <summary>
31 /// 成绩
32 /// </summary>
33 public DbSet<ScoreEntity> Scores { get; set; }
34
35 public DataContext(DbContextOptions options) : base(options)
36 {
37
38 }
39
40 protected override void OnModelCreating(ModelBuilder modelBuilder)
41 {
42 base.OnModelCreating(modelBuilder);
43 modelBuilder.Entity<UserEntity>().ToTable("Users");
44 modelBuilder.Entity<MenuEntity>().ToTable("Menus");
45 modelBuilder.Entity<StudentEntity>().ToTable("Students");
46 modelBuilder.Entity<RoleEntity>().ToTable("Roles");
47 modelBuilder.Entity<UserRoleEntity>().ToTable("UserRoles");
48 modelBuilder.Entity<RoleMenuEntity>().ToTable("RoleMenus");
49 }
50 }
51 }
数据服务Service
数据服务是对DataContext操作的封装，使得业务更加明确，当然如果通过控制器直接访问DataContext，省掉数据服务，也可以实现对应功能，只是加入数据服务层，使得结构更加清晰。
数据服务接口ICourseAppService，提供了五个接口，包括查询课程列表，查询当个课程信息，新增课程，修改课程，删除课程，具体如下所示：
1 namespace SIMS.WebApi.Services.Course
2 {
3 public interface ICourseAppService
4 {
5 /// <summary>
6 /// 查询列表
7 /// </summary>
8 /// <param name="courseName"></param>
9 /// <param name="teacher"></param>
10 /// <param name="pageNum"></param>
11 /// <param name="pageSize"></param>
12 /// <returns></returns>
13 public PagedRequest<CourseEntity> GetCourses(string courseName,string teacher, int pageNum,int pageSize);
14
15 /// <summary>
16 /// 通过id查询课程信息
17 /// </summary>
18 /// <param name="id"></param>
19 /// <returns></returns>
20 public CourseEntity GetCourse(int id);
21
22 /// <summary>
23 /// 新增课程
24 /// </summary>
25 /// <param name="course"></param>
26 /// <returns></returns>
27 public int AddCourse(CourseEntity course);
28
29 /// <summary>
30 /// 修改课程
31 /// </summary>
32 /// <param name="course"></param>
33 /// <returns></returns>
34 public int UpdateCourse(CourseEntity course);
35
36 /// <summary>
37 /// 删除课程
38 /// </summary>
39 /// <param name="id"></param>
40 public int DeleteCourse(int id);
41 }
42 }
数据服务接口实现类CourseAppService，对数据服务接口ICourseAppService的实现，即通过操作DataContext来访问数据库中的课程表，如下所示：
1 namespace SIMS.WebApi.Services.Course
2 {
3 public class CourseAppService : ICourseAppService
4 {
5 private DataContext dataContext;
6
7 public CourseAppService(DataContext dataContext)
8 {
9 this.dataContext = dataContext;
10 }
11
12 public int AddCourse(CourseEntity course)
13 {
14 var entry = dataContext.Courses.Add(course);
15 dataContext.SaveChanges();
16 return 0;
17 }
18
19 public int DeleteCourse(int id)
20 {
21 var entity = dataContext.Courses.FirstOrDefault(x => x.Id == id);
22 if (entity != null)
23 {
24 dataContext.Courses.Remove(entity);
25 dataContext.SaveChanges();
26 }
27 return 0;
28 }
29
30 /// <summary>
31 /// 根据ID获取单个课程
32 /// </summary>
33 /// <param name="id"></param>
34 /// <returns></returns>
35 public CourseEntity GetCourse(int id)
36 {
37 var entity = dataContext.Courses.FirstOrDefault(r => r.Id == id);
38 return entity;
39 }
40
41 /// <summary>
42 /// 获取课程列表
43 /// </summary>
44 /// <param name="courseName"></param>
45 /// <param name="teacher"></param>
46 /// <param name="pageNum"></param>
47 /// <param name="pageSize"></param>
48 /// <returns></returns>
49 public PagedRequest<CourseEntity> GetCourses(string courseName, string teacher, int pageNum, int pageSize)
50 {
51 IQueryable<CourseEntity> courses = null;
52 if (!string.IsNullOrEmpty(courseName) && !string.IsNullOrEmpty(teacher))
53 {
54 courses = dataContext.Courses.Where(r => r.Name.Contains(courseName) && r.Teacher.Contains(teacher)).OrderBy(r => r.Id);
55 }
56 else if (!string.IsNullOrEmpty(courseName))
57 {
58 courses = dataContext.Courses.Where(r => r.Name.Contains(courseName)).OrderBy(r => r.Id);
59 }
60 else if (!string.IsNullOrEmpty(teacher))
61 {
62 courses = dataContext.Courses.Where(r => r.Teacher.Contains(teacher)).OrderBy(r => r.Id);
63 }
64 else
65 {
66 courses = dataContext.Courses.Where(r => true).OrderBy(r => r.Id);
67 }
68 int count = courses.Count();
69 List<CourseEntity> items;
70 if (pageSize > 0)
71 {
72 items = courses.Skip((pageNum - 1) * pageSize).Take(pageSize).ToList();
73 }
74 else
75 {
76 items = courses.ToList();
77 }
78 return new PagedRequest<CourseEntity>()
79 {
80 count = count,
81 items = items
82 };
83 }
84
85 public int UpdateCourse(CourseEntity course)
86 {
87 dataContext.Courses.Update(course);
88 dataContext.SaveChanges();
89 return 0;
90 }
91 }
92 }
WebApi接口控制器
控制器是对数据服务的公开，每一个控制器的方法表示一个Action，即表示一个客户端可以访问的入口。具体如下所示：
1 namespace SIMS.WebApi.Controllers
2 {
3 /// <summary>
4 /// 课程控制器
5 /// </summary>
6 [Route("api/[controller]/[action]")]
7 [ApiController]
8 public class CourseController : ControllerBase
9 {
10 private readonly ILogger<CourseController> logger;
11
12 private readonly ICourseAppService courseAppService;
13
14 public CourseController(ILogger<CourseController> logger, ICourseAppService courseAppService)
15 {
16 this.logger = logger;
17 this.courseAppService = courseAppService;
18 }
19
20 [HttpGet]
21 public PagedRequest<CourseEntity> GetCourses( int pageNum, int pageSize, string? courseName=null, string? teacher=null) {
22 return courseAppService.GetCourses(courseName,teacher,pageNum,pageSize);
23 }
24
25 /// <summary>
26 /// 获取课程信息
27 /// </summary>
28 /// <param name="id"></param>
29 /// <returns></returns>
30 [HttpGet]
31 public CourseEntity GetCourse(int id)
32 {
33 return courseAppService.GetCourse(id);
34 }
35
36 /// <summary>
37 /// 新增课程
38 /// </summary>
39 /// <param name="course"></param>
40 /// <returns></returns>
41 [HttpPost]
42 public int AddCourse(CourseEntity course)
43 {
44 return courseAppService.AddCourse(course);
45 }
46
47 /// <summary>
48 /// 修改课程
49 /// </summary>
50 /// <param name="course"></param>
51 /// <returns></returns>
52 [HttpPut]
53 public int UpdateCourse(CourseEntity course)
54 {
55 return courseAppService.UpdateCourse(course);
56 }
57
58 /// <summary>
59 /// 删除课程
60 /// </summary>
61 /// <param name="id"></param>
62 [HttpDelete]
63 public int DeleteCourse(int id)
64 {
65 return courseAppService.DeleteCourse(id);
66 }
67 }
68 }
当服务运行起来后，Swagger还每一个控制器都进行归类，可以清晰的看到每一个接口对应的网址，课程管理模块对应的接口如下所示：
客户端接口访问类HttpUtil
在学生信息系统开发的过程中，发现所有的接口访问都是通用的，所以对接口访问功能提取成一个HttpUtil基类【包括GET，POST，PUT，DELETE等功能】，其他具体业务再继承基类，并细化具体业务即可。HttpUtil代码如下所示：
1 namespace SIMS.Utils.Http
2 {
3 /// <summary>
4 /// HTTP访问基类
5 /// </summary>
6 public class HttpUtil
7 {
8 private static readonly string absoluteUrl = "https://localhost:7299/";
9
10 /// <summary>
11 /// get方式
12 /// </summary>
13 /// <param name="url"></param>
14 /// <param name="param"></param>
15 /// <returns></returns>
16 public static string Get(string url, Dictionary<string, object> param)
17 {
18 string p=string.Empty;
19 if (param != null && param.Count() > 0) {
20 foreach (var keypair in param)
21 {
22 if (keypair.Value != null)
23 {
24 p += $"{keypair.Key}={keypair.Value}&";
25 }
26 }
27 }
28 if (!string.IsNullOrEmpty(p)) {
29 p=p.TrimEnd('&');
30 }
31 var httpClient = new HttpClient();
32 var response = httpClient.GetAsync($"{absoluteUrl}{url}?{p}",HttpCompletionOption.ResponseContentRead).Result;
33 string strJson = string.Empty;
34 Stream stream = response.Content.ReadAsStream();
35 using (StreamReader reader = new StreamReader(stream, Encoding.UTF8))
36 {
37 strJson = reader.ReadToEnd();
38 }
39 return strJson;
40 }
41
42 /// <summary>
43 /// POST方式
44 /// </summary>
45 /// <param name="url"></param>
46 /// <param name="param"></param>
47 /// <returns></returns>
48 public static string Post<T>(string url, T t)
49 {
50 var content = JsonConvert.SerializeObject(t);
51
52 var httpContent = new StringContent(content,Encoding.UTF8,"application/json");
53 var httpClient = new HttpClient();
54 var response = httpClient.PostAsync($"{absoluteUrl}{url}", httpContent).Result;
55
56 var respContent = response.Content.ReadAsStringAsync().Result;
57 return respContent;
58 }
59
60 public static string Put<T>(string url, T t) {
61 var content = JsonConvert.SerializeObject(t);
62
63 var httpContent = new StringContent(content,Encoding.UTF8,"application/json");
64 var httpClient = new HttpClient();
65 var response = httpClient.PutAsync($"{absoluteUrl}{url}", httpContent).Result;
66
67 var respContent = response.Content.ReadAsStringAsync().Result;
68 return respContent;
69 }
70
71 public static string Delete(string url, Dictionary<string, string> param) {
72 string p = string.Empty;
73 if (param != null && param.Count() > 0)
74 {
75 foreach (var keypair in param)
76 {
77 p += $"{keypair.Key}={keypair.Value}&";
78 }
79 }
80 if (!string.IsNullOrEmpty(p))
81 {
82 p = p.TrimEnd('&');
83 }
84 var httpClient = new HttpClient();
85 var response = httpClient.DeleteAsync($"{absoluteUrl}{url}?{p}").Result;
86 var respContent = response.Content.ReadAsStringAsync().Result;
87 return respContent;
88 }
89
90
91 public static T StrToObject<T>(string str) {
92 var t = JsonConvert.DeserializeObject<T>(str);
93 return t;
94 }
95 }
96 }
然后课课程接口访问通用类CourseHttpUtil继承了HttpUtil，以对应课程信息的操作。如下所示：
1 namespace SIMS.Utils.Http
2 {
3 public class CourseHttpUtil:HttpUtil
4 {
5 /// <summary>
6 /// 通过id查询课程信息
7 /// </summary>
8 /// <param name="id"></param>
9 /// <returns></returns>
10 public static CourseEntity GetCourse(int id)
11 {
12 Dictionary<string, object> data = new Dictionary<string, object>();
13 data["id"] = id;
14 var str = Get(UrlConfig.COURSE_GETCOURSE, data);
15 var course = StrToObject<CourseEntity>(str);
16 return course;
17 }
18
19 public static PagedRequest<CourseEntity> GetCourses(string? courseName, string? teacher, int pageNum, int pageSize)
20 {
21 Dictionary<string, object> data = new Dictionary<string, object>();
22 data["courseName"] = courseName;
23 data["teacher"] = teacher;
24 data["pageNum"] = pageNum;
25 data["pageSize"] = pageSize;
26 var str = Get(UrlConfig.COURSE_GETCOURSES, data);
27 var courses = StrToObject<PagedRequest<CourseEntity>>(str);
28 return courses;
29 }
30
31 public static bool AddCourse(CourseEntity course)
32 {
33 var ret = Post<CourseEntity>(UrlConfig.COURSE_ADDCOURSE, course);
34 return int.Parse(ret) == 0;
35 }
36
37 public static bool UpdateCourse(CourseEntity course)
38 {
39 var ret = Put<CourseEntity>(UrlConfig.SCORE_UPDATESCORE, course);
40 return int.Parse(ret) == 0;
41 }
42
43 public static bool DeleteCourse(int Id)
44 {
45 Dictionary<string, string> data = new Dictionary<string, string>();
46 data["Id"] = Id.ToString();
47 var ret = Delete(UrlConfig.COURSE_DELETECOURSE, data);
48 return int.Parse(ret) == 0;
49 }
50 }
51 }
客户端操作
经过前面四个部分的开发，客户端就可以与数据接口进行交互，展示数据到客户端。客户端所有的开发，均采用MVVM模式进行。
在课程管理模块中，根据功能区分，主要包含两个View视图及对应的ViewModel。如下所示：
- Course视图，主要用于课程的查询，以及新增，修改，删除的链接入口。
- AddEditCourse视图，主要用于课程信息的新增和修改，共用一个视图页面。
- 删除课程不需要页面，所以没有对应视图。
1. Course视图
Course视图，主要是课程的查询和新增，修改，删除的链接入口。涉及知识点如下：
- Course视图页面布局采用Grid方式和StackPanel混合布局，即整体布局采用Grid，细微布局采用StackPanel。
- 课程采用分页列表的方式展示，需要用到DataGrid，及分页控件【WPF默认不提供分页控件，可自行编写分页控件】。
- 查询条件采用按钮Button和文本框TextBox等组成，关于基础控件的使用，不再详细论述，可参考其他文章。
- 在本系统的所有WPF视图中，均需要引入Prism和 MAH组件。
- Course视图中，所有的数据均采用Binding的方式与ViewModel进行交互。
Course视图具体代码，如下所示：
1 <UserControl x:Class="SIMS.CourseModule.Views.Course"
2 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
3 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
4 xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
5 xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
6 xmlns:local="clr-namespace:SIMS.CourseModule.Views"
7 xmlns:i="http://schemas.microsoft.com/xaml/behaviors"
8 xmlns:prism="http://prismlibrary.com/"
9 xmlns:mahApps="http://metro.mahapps.com/winfx/xaml/controls"
10 prism:ViewModelLocator.AutoWireViewModel="True"
11 xmlns:ctrls ="clr-namespace:SIMS.Utils.Controls;assembly=SIMS.Utils"
12 mc:Ignorable="d"
13 d:DesignHeight="450" d:DesignWidth="800">
14 <UserControl.Resources>
15 <ResourceDictionary>
16 <ResourceDictionary.MergedDictionaries>
17 <ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Controls.xaml" />
18 <ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Themes/Light.Blue.xaml" />
19 <ResourceDictionary>
20 <Style x:Key="LinkButton" TargetType="Button">
21 <Setter Property="Background" Value="White"></Setter>
22 <Setter Property="Cursor" Value="Hand"></Setter>
23 <Setter Property="Margin" Value="3"></Setter>
24 <Setter Property="MinWidth" Value="80"></Setter>
25 <Setter Property="MinHeight" Value="25"></Setter>
26 <Setter Property="BorderThickness" Value="0 0 0 0"></Setter>
27 </Style>
28 </ResourceDictionary>
29 </ResourceDictionary.MergedDictionaries>
30 </ResourceDictionary>
31 </UserControl.Resources>
32 <i:Interaction.Triggers>
33 <i:EventTrigger EventName="Loaded">
34 <i:InvokeCommandAction Command="{Binding LoadedCommand}"></i:InvokeCommandAction>
35 </i:EventTrigger>
36 </i:Interaction.Triggers>
37 <Grid>
38 <Grid.RowDefinitions>
39 <RowDefinition Height="Auto"></RowDefinition>
40 <RowDefinition Height="Auto"></RowDefinition>
41 <RowDefinition Height="*"></RowDefinition>
42 <RowDefinition Height="Auto"></RowDefinition>
43 </Grid.RowDefinitions>
44 <TextBlock Text="课程信息" FontSize="20" Background="AliceBlue" Margin="2"></TextBlock>
45 <StackPanel Grid.Row="1" Orientation="Horizontal" VerticalAlignment="Center">
46 <TextBlock Text="课程名称" VerticalAlignment="Center" Margin="2"></TextBlock>
47 <TextBox Margin="4" MinWidth="120" Height="30"
48 Text="{Binding CourseName}"
49 HorizontalContentAlignment="Stretch"
50 mahApps:TextBoxHelper.ClearTextButton="True"
51 mahApps:TextBoxHelper.Watermark="课程名称"
52 mahApps:TextBoxHelper.WatermarkAlignment="Left"
53 SpellCheck.IsEnabled="True" />
54 <TextBlock Text="老师" VerticalAlignment="Center" Margin="2"></TextBlock>
55 <TextBox Margin="4" MinWidth="120" Height="30"
56 Text="{Binding Teacher}"
57 HorizontalContentAlignment="Stretch"
58 mahApps:TextBoxHelper.ClearTextButton="True"
59 mahApps:TextBoxHelper.Watermark="老师"
60 mahApps:TextBoxHelper.WatermarkAlignment="Left"
61 SpellCheck.IsEnabled="True" />
62 <Button Content="查询" Style="{DynamicResource MahApps.Styles.Button.Square.Accent}" Width="120" Height="30" Margin="3" Command="{Binding QueryCommand}"></Button>
63 <Button Content="新增" Style="{DynamicResource MahApps.Styles.Button.Square.Accent}" Width="120" Height="30" Margin="3" Command="{Binding AddCommand}"></Button>
64 </StackPanel>
65 <DataGrid x:Name="dgClasses"
66 Grid.Row="2"
67 Grid.Column="0"
68 Margin="2"
69 AutoGenerateColumns="False"
70 CanUserAddRows="False"
71 CanUserDeleteRows="False"
72 ItemsSource="{Binding Courses}"
73 RowHeaderWidth="0">
74 <DataGrid.Columns>
75 <DataGridTextColumn Binding="{Binding Name}" Header="课程名称" Width="*" />
76 <DataGridTextColumn Binding="{Binding Teacher}" Header="老师" Width="*"/>
77 <DataGridTextColumn Binding="{Binding CreateTime, StringFormat=yyyy-MM-dd HH:mm:ss}" Header="创建时间" Width="*"/>
78 <DataGridTextColumn Binding="{Binding LastEditTime,StringFormat=yyyy-MM-dd HH:mm:ss}" Header="最后修改时间" Width="*"/>
79 <DataGridTemplateColumn Header="操作" Width="*">
80 <DataGridTemplateColumn.CellTemplate>
81 <DataTemplate>
82 <StackPanel Orientation="Horizontal">
83 <Button Content="Edit" Style="{StaticResource LinkButton}" Command="{Binding RelativeSource={RelativeSource AncestorType=DataGrid, Mode=FindAncestor}, Path=DataContext.EditCommand}" CommandParameter="{Binding Id}">
84 <Button.Template>
85 <ControlTemplate TargetType="Button">
86 <TextBlock TextDecorations="Underline" HorizontalAlignment="Center">
87 <ContentPresenter />
88 </TextBlock>
89 </ControlTemplate>
90 </Button.Template>
91 </Button>
92 <Button Content="Delete" Style="{StaticResource LinkButton}" Command="{Binding RelativeSource={RelativeSource AncestorType=DataGrid, Mode=FindAncestor}, Path=DataContext.DeleteCommand}" CommandParameter="{Binding Id}">
93 <Button.Template>
94 <ControlTemplate TargetType="Button">
95 <TextBlock TextDecorations="Underline" HorizontalAlignment="Center">
96 <ContentPresenter />
97 </TextBlock>
98 </ControlTemplate>
99 </Button.Template>
100 </Button>
101 </StackPanel>
102 </DataTemplate>
103 </DataGridTemplateColumn.CellTemplate>
104 </DataGridTemplateColumn>
105 </DataGrid.Columns>
106 </DataGrid>
107 <ctrls:PageControl Grid.Row="3" DataContext="{Binding}" ></ctrls:PageControl>
108 </Grid>
109 </UserControl>
2. CourseViewModel
CourseViewModel是页面视图的业务逻辑处理，如处理客户端的点击的命令等内容。主要分为三部分：
数据绑定
数据绑定，如查询条件的文本框内容的绑定，课程查询列表的绑定。其中数据访问采用CourseHttpUtil工具类，如下所示：
1 #region 属性及构造函数
2
3 /// <summary>
4 /// 专业
5 /// </summary>
6 private string courseName;
7
8 public string CourseName
9 {
10 get { return courseName; }
11 set { SetProperty(ref courseName, value); }
12 }
13
14 /// <summary>
15 /// 年级
16 /// </summary>
17 private string teacher;
18
19 public string Teacher
20 {
21 get { return teacher; }
22 set { SetProperty(ref teacher, value); }
23 }
24
25
26
27 private ObservableCollection<CourseEntity> courses;
28
29 public ObservableCollection<CourseEntity> Courses
30 {
31 get { return courses; }
32 set { SetProperty(ref courses, value); }
33 }
34
35 private IDialogService dialogService;
36
37 public CourseViewModel(IDialogService dialogService)
38 {
39 this.dialogService = dialogService;
40 this.pageNum = 1;
41 this.pageSize = 20;
42 }
43
44 private void InitInfo()
45 {
46 Courses = new ObservableCollection<CourseEntity>();
47 var pagedRequst = CourseHttpUtil.GetCourses(this.CourseName, this.Teacher, this.pageNum, this.pageSize);
48 var entities = pagedRequst.items;
49 Courses.AddRange(entities);
50 //
51 this.TotalCount = pagedRequst.count;
52 this.TotalPage = ((int)Math.Ceiling(this.TotalCount * 1.0 / this.pageSize));
53 }
54
55 #endregion
命令绑定
在课程页面，查询按钮，编辑按钮，删除按钮，均与ViewModel中的命令进行绑定，如下所示：
1 #region 事件
2
3 private DelegateCommand loadedCommand;
4
5 public DelegateCommand LoadedCommand
6 {
7 get
8 {
9 if (loadedCommand == null)
10 {
11 loadedCommand = new DelegateCommand(Loaded);
12 }
13 return loadedCommand;
14 }
15 }
16
17 private void Loaded()
18 {
19 InitInfo();
20 }
21
22 private DelegateCommand queryCommand;
23
24 public DelegateCommand QueryCommand
25 {
26 get
27 {
28 if (queryCommand == null)
29 {
30 queryCommand = new DelegateCommand(Query);
31 }
32 return queryCommand;
33 }
34 }
35
36 private void Query()
37 {
38 this.pageNum = 1;
39 this.InitInfo();
40 }
41
42 /// <summary>
43 /// 新增命令
44 /// </summary>
45 private DelegateCommand addCommand;
46
47 public DelegateCommand AddCommand
48 {
49 get
50 {
51 if (addCommand == null)
52 {
53 addCommand = new DelegateCommand(Add);
54 }
55 return addCommand;
56 }
57 }
58
59 private void Add()
60 {
61 this.dialogService.ShowDialog("addEditCourse", null, AddEditCallBack, "MetroDialogWindow");
62 }
63
64 private void AddEditCallBack(IDialogResult dialogResult)
65 {
66 if (dialogResult != null && dialogResult.Result == ButtonResult.OK)
67 {
68 //刷新列表
69 this.pageNum = 1;
70 this.InitInfo();
71 }
72 }
73
74 /// <summary>
75 /// 编辑命令
76 /// </summary>
77 private DelegateCommand<object> editCommand;
78
79 public DelegateCommand<object> EditCommand
80 {
81 get
82 {
83 if (editCommand == null)
84 {
85 editCommand = new DelegateCommand<object>(Edit);
86 }
87 return editCommand;
88 }
89 }
90
91 private void Edit(object obj)
92 {
93 if (obj == null)
94 {
95 return;
96 }
97 var Id = int.Parse(obj.ToString());
98 var course = this.Courses.FirstOrDefault(r => r.Id == Id);
99 if (course == null)
100 {
101 MessageBox.Show("无效的课程ID");
102 return;
103 }
104 IDialogParameters dialogParameters = new DialogParameters();
105 dialogParameters.Add("course", course);
106 this.dialogService.ShowDialog("addEditCourse", dialogParameters, AddEditCallBack, "MetroDialogWindow");
107 }
108
109 /// <summary>
110 /// 编辑命令
111 /// </summary>
112 private DelegateCommand<object> deleteCommand;
113
114 public DelegateCommand<object> DeleteCommand
115 {
116 get
117 {
118 if (deleteCommand == null)
119 {
120 deleteCommand = new DelegateCommand<object>(Delete);
121 }
122 return deleteCommand;
123 }
124 }
125
126 private void Delete(object obj)
127 {
128 if (obj == null)
129 {
130 return;
131 }
132 var Id = int.Parse(obj.ToString());
133 var course = this.Courses.FirstOrDefault(r => r.Id == Id);
134 if (course == null)
135 {
136 MessageBox.Show("无效的班级ID");
137 return;
138 }
139 if (MessageBoxResult.Yes != MessageBox.Show("Are you sure to delete?", "Confirm", MessageBoxButton.YesNo)) {
140 return;
141 }
142 bool flag = CourseHttpUtil.DeleteCourse(Id);
143 if (flag)
144 {
145 this.pageNum = 1;
146 this.InitInfo();
147 }
148 }
149
150 #endregion
分页命令与数据绑定
关于分页功能，是通用的功能，几乎每一个查询页面的分页都大同小异，可以进行复制粘贴，快速实现功能。如下所示：
1 #region 分页
2
3 /// <summary>
4 /// 当前页码
5 /// </summary>
6 private int pageNum;
7
8 public int PageNum
9 {
10 get { return pageNum; }
11 set { SetProperty(ref pageNum, value); }
12 }
13
14 /// <summary>
15 /// 每页显示多少条记录
16 /// </summary>
17 private int pageSize;
18
19 public int PageSize
20 {
21 get { return pageSize; }
22 set { SetProperty(ref pageSize, value); }
23 }
24
25 /// <summary>
26 ///总条数
27 /// </summary>
28 private int totalCount;
29
30 public int TotalCount
31 {
32 get { return totalCount; }
33 set { SetProperty(ref totalCount, value); }
34 }
35
36 /// <summary>
37 ///总页数
38 /// </summary>
39 private int totalPage;
40
41 public int TotalPage
42 {
43 get { return totalPage; }
44 set { SetProperty(ref totalPage, value); }
45 }
46
47
48 /// <summary>
49 /// 跳转页
50 /// </summary>
51 private int jumpNum;
52
53 public int JumpNum
54 {
55 get { return jumpNum; }
56 set { SetProperty(ref jumpNum, value); }
57 }
58
59 /// <summary>
60 /// 首页命令
61 /// </summary>
62 private DelegateCommand firstPageCommand;
63
64 public DelegateCommand FirstPageCommand
65 {
66 get
67 {
68 if (firstPageCommand == null)
69 {
70 firstPageCommand = new DelegateCommand(FirstPage);
71 }
72 return firstPageCommand;
73 }
74
75 }
76
77 private void FirstPage()
78 {
79 this.PageNum = 1;
80 this.InitInfo();
81 }
82
83 /// <summary>
84 /// 跳转页命令
85 /// </summary>
86 private DelegateCommand jumpPageCommand;
87
88 public DelegateCommand JumpPageCommand
89 {
90 get
91 {
92 if (jumpPageCommand == null)
93 {
94 jumpPageCommand = new DelegateCommand(JumpPage);
95 }
96 return jumpPageCommand;
97 }
98 }
99
100 private void JumpPage()
101 {
102 if (jumpNum < 1)
103 {
104 MessageBox.Show("请输入跳转页");
105 return;
106 }
107 if (jumpNum > this.totalPage)
108 {
109 MessageBox.Show($"跳转页面必须在[1,{this.totalPage}]之间，请确认。");
110 return;
111 }
112 this.PageNum = jumpNum;
113
114 this.InitInfo();
115 }
116
117 /// <summary>
118 /// 前一页
119 /// </summary>
120 private DelegateCommand prevPageCommand;
121
122 public DelegateCommand PrevPageCommand
123 {
124 get
125 {
126 if (prevPageCommand == null)
127 {
128 prevPageCommand = new DelegateCommand(PrevPage);
129 }
130 return prevPageCommand;
131 }
132 }
133
134 private void PrevPage()
135 {
136 this.PageNum--;
137 if (this.PageNum < 1)
138 {
139 this.PageNum = 1;
140 }
141 this.InitInfo();
142 }
143
144 /// <summary>
145 /// 下一页命令
146 /// </summary>
147 private DelegateCommand nextPageCommand;
148
149 public DelegateCommand NextPageCommand
150 {
151 get
152 {
153 if (nextPageCommand == null)
154 {
155 nextPageCommand = new DelegateCommand(NextPage);
156 }
157 return nextPageCommand;
158 }
159 }
160
161 private void NextPage()
162 {
163 this.PageNum++;
164 if (this.PageNum > this.TotalPage)
165 {
166 this.PageNum = this.TotalPage;
167 }
168 this.InitInfo();
169 }
170
171 #endregion
3. 新增编辑课程视图AddEditCourse
新增编辑课程视图，主要用于对课程的修改和新增，可通过查询页面的新增按钮和具体课程的编辑按钮弹出对应窗口。如下所示：
1 <UserControl x:Class="SIMS.CourseModule.Views.AddEditCourse"
2 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
3 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
4 xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
5 xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
6 xmlns:local="clr-namespace:SIMS.CourseModule.Views"
7 mc:Ignorable="d"
8 xmlns:i="http://schemas.microsoft.com/xaml/behaviors"
9 xmlns:mahApps ="http://metro.mahapps.com/winfx/xaml/controls"
10 xmlns:prism="http://prismlibrary.com/"
11 d:DesignHeight="400" d:DesignWidth="600">
12 <prism:Dialog.WindowStyle>
13 <Style TargetType="Window">
14 <Setter Property="Width" Value="600"></Setter>
15 <Setter Property="Height" Value="400"></Setter>
16 </Style>
17 </prism:Dialog.WindowStyle>
18 <UserControl.Resources>
19 <ResourceDictionary>
20 <ResourceDictionary.MergedDictionaries>
21 <ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Controls.xaml" />
22 <ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Themes/Light.Blue.xaml" />
23 </ResourceDictionary.MergedDictionaries>
24 </ResourceDictionary>
25 </UserControl.Resources>
26 <i:Interaction.Triggers>
27 <i:EventTrigger EventName="Loaded">
28 <i:InvokeCommandAction Command="{Binding LoadedCommand}"></i:InvokeCommandAction>
29 </i:EventTrigger>
30 </i:Interaction.Triggers>
31 <Grid>
32 <Grid.ColumnDefinitions>
33 <ColumnDefinition Width="0.2*"></ColumnDefinition>
34 <ColumnDefinition Width="Auto"></ColumnDefinition>
35 <ColumnDefinition Width="*"></ColumnDefinition>
36 <ColumnDefinition Width="0.2*"></ColumnDefinition>
37 </Grid.ColumnDefinitions>
38 <Grid.RowDefinitions>
39 <RowDefinition></RowDefinition>
40 <RowDefinition></RowDefinition>
41 <RowDefinition></RowDefinition>
42 </Grid.RowDefinitions>
43
44
45 <TextBlock Text="课程名称" Grid.Row="0" Grid.Column="1" VerticalAlignment="Center" Margin="3"></TextBlock>
46 <TextBox Grid.Row="0" Grid.Column="2" MinWidth="120" Height="35" VerticalAlignment="Center" Margin="3" Text="{Binding Course.Name}"></TextBox>
47 <TextBlock Text="授课老师" Grid.Row="1" Grid.Column="1" VerticalAlignment="Center" Margin="3"></TextBlock>
48 <TextBox Grid.Row="1" Grid.Column="2" MinWidth="120" Height="35" VerticalAlignment="Center" Margin="3" Text="{Binding Course.Teacher}"></TextBox>
49
50 <StackPanel Grid.Row="2" Grid.Column="1" Grid.ColumnSpan="2" Orientation="Horizontal" HorizontalAlignment="Center" Margin="3">
51 <Button Content="取消" Margin="5" MinWidth="120" Height="35" Style="{DynamicResource MahApps.Styles.Button.Square.Accent}" Command="{Binding CancelCommand}"></Button>
52 <Button Content="保存" Margin="5" MinWidth="120" Height="35" Style="{DynamicResource MahApps.Styles.Button.Square.Accent}" Command="{Binding SaveCommand}"></Button>
53 </StackPanel>
54
55 </Grid>
56 </UserControl>
4. 新增编辑课程ViewModel
AddEditCourseViewModel是对页面具体功能的业务封装，主要是对应课程信息的保存，也包括数据绑定和命令绑定等内容，如下所示：
1 namespace SIMS.CourseModule.ViewModels
2 {
3 public class AddEditCourseViewModel:BindableBase,IDialogAware
4 {
5 #region 属性和构造函数
6
7 /// <summary>
8 /// 班级实体
9 /// </summary>
10 private CourseEntity course;
11
12 public CourseEntity Course
13 {
14 get { return course; }
15 set { SetProperty(ref course, value); }
16 }
17
18 public AddEditCourseViewModel()
19 {
20
21 }
22
23 #endregion
24
25 #region Command
26
27 private DelegateCommand loadedCommand;
28
29 public DelegateCommand LoadedCommand
30 {
31 get
32 {
33 if (loadedCommand == null)
34 {
35 loadedCommand = new DelegateCommand(Loaded);
36 }
37 return loadedCommand;
38 }
39 }
40
41 private void Loaded()
42 {
43 }
44
45 private DelegateCommand cancelCommand;
46
47 public DelegateCommand CancelCommand
48 {
49 get
50 {
51 if (cancelCommand == null)
52 {
53 cancelCommand = new DelegateCommand(Cancel);
54 }
55 return cancelCommand;
56 }
57 }
58
59 private void Cancel()
60 {
61 RequestClose?.Invoke((new DialogResult(ButtonResult.Cancel)));
62 }
63
64 private DelegateCommand saveCommand;
65
66 public DelegateCommand SaveCommand
67 {
68 get
69 {
70 if (saveCommand == null)
71 {
72 saveCommand = new DelegateCommand(Save);
73 }
74 return saveCommand;
75 }
76 }
77
78 private void Save()
79 {
80 if (Course != null)
81 {
82 Course.CreateTime = DateTime.Now;
83 Course.LastEditTime = DateTime.Now;
84
85 bool flag = false;
86 if (Course.Id > 0)
87 {
88 flag = CourseHttpUtil.UpdateCourse(Course);
89 }
90 else
91 {
92 flag = CourseHttpUtil.AddCourse(Course);
93 }
94 if (flag)
95 {
96 RequestClose?.Invoke((new DialogResult(ButtonResult.OK)));
97 }
98 }
99 }
100
101
102 #endregion
103
104 #region 对话框
105
106 public string Title => "新增或编辑课程信息";
107
108 public event Action<IDialogResult> RequestClose;
109
110 public bool CanCloseDialog()
111 {
112 return true;
113 }
114
115 public void OnDialogClosed()
116 {
117
118 }
119
120 public void OnDialogOpened(IDialogParameters parameters)
121 {
122 if (parameters != null && parameters.ContainsKey("course"))
123 {
124 this.Course = parameters.GetValue<CourseEntity>("course");
125 }
126 else
127 {
128 this.Course = new CourseEntity();
129 }
130 }
131
132 #endregion
133
134 }
135 }
注意：因为新增编辑页面是弹出窗口，所以在Prism框架中，需要实现IDialogAware接口。
5. 控件注册
当页面功能开发完成后，在通过Prism进行注册，就可以通过导航栏和弹出窗口进行展示，如下所示：
1 namespace SIMS.CourseModule
2 {
3 public class CourseModule : IModule
4 {
5 public void OnInitialized(IContainerProvider containerProvider)
6 {
7
8 }
9
10 public void RegisterTypes(IContainerRegistry containerRegistry)
11 {
12 containerRegistry.RegisterForNavigation<Course, CourseViewModel>(nameof(Course));
13 containerRegistry.RegisterDialog<AddEditCourse, AddEditCourseViewModel>("addEditCourse");
14 }
15 }
16 }
示例效果图
经过上述步骤后，课程管理模块就开发完成，运行VS后，效果如下所示：
总结
经过上述步骤，不难看出，开发一个完整的功能，涉及到前端，后端，接口访问，数据库等相关内容，麻雀虽小，五脏俱全。其实开发一个课程管理模块，就是对数据库中课程表的增删改查，也可以把所有代码都糅合在一起，简化开发流程和步骤，这样代码量将大幅度减少。但是分层，分模块并不是为了使项目复杂化，而为了更加清晰以及便于维护与扩展，也是本篇文章希望为大家传递的一种开发理念。
备注
江上渔者【作者】范仲淹 【朝代】宋
江上往来人，但爱鲈鱼美。
君看一叶舟，出没风波里。
标签：WebApi,DelegateCommand,return,string,int,private,Prism,WPF,public 来源： https://www.cnblogs.com/hsiang/p/16322653.html
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