Question

enter code here我已经成功完成了ID，名称，出生日期，性别的Student表的CRUD，但是当我尝试使用名为StudentCourse的子表进行输入时，该表有多个StudentCourse项，这是行不通的。

我为StudentCourse添加了一个Multiselect Dropdown，但它是从api检索数据但未绑定

任何人都有一个想法如何使子表成为可能。这是我的代码

 @page "/studentpost"
    @using BlazorApp.Shared.Models
    @using BlazorApp.Shared.Enums
    @inject NavigationManager NavigationManager
    @inject HttpClient Http


    <h3>Add Student Details</h3>

    <div>
        <EditForm Model="@student">
            <DataAnnotationsValidator />
            <ValidationSummary />
            <table class="form-group">
                <tr>
                    <td>
                        <label for="Name" class="control-label">Student Name</label>
                    </td>
                    <td>
                        <InputText class="form-control" @bind-Value="@student.Name" />
                        <ValidationMessage For="@(() => student.Name)" />
                    </td>
                </tr>
                <tr class="pt-5">
                    <td>
                        <label for="Email" class="control-label">BirthDate</label>
                    </td>
                    <td>
                        <InputDate class="form-control" @bind-Value="@student.BirthDate" />
                        <ValidationMessage For="@(() => student.BirthDate)" />
                    </td>
                </tr>
                <tr class="pt-5">
                    <td>
                        <label for="Name" class="control-label">Gender</label>
                    </td>
                    <td>

                        <InputSelect id="DdlGender" @bind-Value="student.Gender">
                            <option value="0">-- Select Gender --</option>
                            <option value="@Gender.Type.Male">@Gender.Type.Male.ToString()</option>
                            <option value="@Gender.Type.Female">@Gender.Type.Female.ToString()</option>
                            <option value="@Gender.Type.TransGender">@Gender.Type.TransGender.ToString()</option>
                        </InputSelect>
                        <ValidationMessage For="@(() => student.Gender)" />
                    </td>
                </tr>
                <tr class="pt-5">
                    <td>
                        <label for="Name" class="control-label">Course</label>
                    </td>

                    <td>

                        <InputSelect id="DdlCourse" @bind-Value="courses">
                            <option value="0">-- Select Gender --</option>
                            @foreach (var itm in courses)
                            {
                                <option value="@itm.Id">@itm.CourseName.ToString()</option>
                            }
                        </InputSelect>

                    </td>
                </tr>
                <tr class="pt-5">
                    <td>
                        <button type="submit" class="btn btn-success" @onclick="@(async ()=> await AddStudent())">Save</button>
                    </td>
                    <td>
                        <button type="submit" class="btn btn-success" @onclick="Cancel">Cancel</button>
                    </td>
                </tr>
            </table>
        </EditForm>
    </div>

    @code {
        Student student = null;
        Course[] courses=null;
        //protected override void OnInitialized()
        protected override async Task OnInitializedAsync()
        {
            student = new Student() {Gender=Gender.Type.Female ,BirthDate = DateTime.Now };
            courses=await Http.GetJsonAsync<Course[]>("course"); 
        }

        public async Task<Course[]> GetCourses()
        {
            return await Http.GetJsonAsync<Course[]>("course");
        }
        void BackToList()
        {
            NavigationManager.NavigateTo($"/fetchstudent");
        }

        void Cancel()
        {
            BackToList();
        }


        protected async Task AddStudent()
        {
            await Http.SendJsonAsync(HttpMethod.Post, "student/add", student);
            BackToList();
        }

        //private void GenderChanged(UIChangeEventArgs e)
        //{

        //}
    }

在共享项目中，我从数据库获得模型

public class Student
    {
        public int Id { get; set; }
        [Required ]
        [StringLength(150, ErrorMessage ="Name must be within 150 characters.")]
        public string Name { get; set; }
        [Required]
        public DateTime BirthDate { get; set; }
        [Required]
        [Range(1,3)]
        public Gender.Type Gender { get; set; }

       // public List<int> CourseIds { get; set; }
    }

 public class Course
    {
        public int Id { get; set; }
        public string CourseName { get; set; }
    }

在上下文中，我已经注册了该模型

public class CoreDemoContext : DbContext
    {


        //public CoreDemoContext(DbContextOptions<CoreDemoContext> options) : base(options)
        //{

        //}

        public CoreDemoContext()
        {

        }

        public DbSet<Student> Student { get; set; }
        public DbSet<Course> Course { get; set; }
        public DbSet<StudentCourse> StudentCourse { get; set; }
        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            if (!optionsBuilder.IsConfigured)
            {
                optionsBuilder.UseSqlServer(@"Data Source=RITA-PC\SQLEXPRESS;Initial Catalog=CoreDemo;Persist Security Info=True;User ID=sa;Password=sa@123");
            }
        }
    }

Answer 1

@bind-Value应该是所选项目，而不是数组：

<InputSelect id="DdlCourse" @bind-Value="selectedCourse">

和@code

中

Course selectedCourse = null;

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1 个答案: