(10/30) Everyone learns Blazor together: Blog and Posts

Now we have an interface where we can enter a log, but a log means writing every day. How can only one article be enough? Let's add a blog.

首先新增BlogModel类，里面很简单只有 4 个属性，分别为 Id、名称、日志列表及新增时间。

using System.ComponentModel.DataAnnotations;

namespace BlazorServer.Models;

public class BlogModel
{
	[Key] public int Id { get; set; }

	[MaxLength(10, ErrorMessage = "博客名称太长")]
	public string? Name { get; set; }

	public List<PostModel>? Posts { get; set; }

	public DateTime CreateDateTime { get; set; }
}

接着将Post.razor的@page指示词跟EditForm底下的 Expander 案例移除，打开launchSettings.json将launchUrl改为 Blog，因为我们的首页要改成 Blog。

再把PostBase的OnInitializedAsync中指派值给Post的部分移除，Post上面加入Parameter，表示要从外部传进来。

最后新增BlogBase.cs跟Blog.razor，可以看到BlogBase.cs的OnInitializedAsync调用一个方法LoadData，实体化一个Blog，里面的Posts有 4 条数据。

using BlazorServer.Models;
using Microsoft.AspNetCore.Components;

namespace BlazorServer.Pages;

public class BlogBase : ComponentBase
{
	public BlogModel? Blog { get; set; }

	protected override Task OnInitializedAsync()
	{
		LoadData();
		return base.OnInitializedAsync();
	}

	private void LoadData()
	{
		Blog = new BlogModel
		{
			Id = 1,
			Name = "我的博客",
			Posts = new List<PostModel>
			{
				new PostModel
					{ Id = 1, Title = "标题1", Content = "内容1", CreateDateTime = new(2021, 12, 11, 10, 20, 50) },
				new PostModel { Id = 1, Title = "标题2", Content = "内容2", CreateDateTime = new(2021, 12, 12, 9, 13, 15) },
				new PostModel
					{ Id = 1, Title = "标题3", Content = "内容3", CreateDateTime = new(2021, 12, 13, 20, 31, 26) },
				new PostModel { Id = 1, Title = "标题4", Content = "内容4", CreateDateTime = new(2021, 12, 14, 22, 15, 27) }
			},
			CreateDateTime = new(2021, 12, 14, 23, 46, 59)
		};
	}
}

Blog.razor则是如下图一样，要记住Blog==null的判断很重要，因为真实的数据大都会用异步方式传递，所以取得数据的速度会比画面渲染的时间晚，若没有这样判断，很容易发生 Blazor 找不到该数据而报错的状况。

另外Post.razor也做了相应调整，可以看到画面呈现了博客名称及 4 条日志，这样一来我们就完成了简单的博客雏型了。

Post.razor：

@inherits PostBase

<div class="form-group">
  <label for="CreateDateTime">创建时间</label>
  <input
    type="text"
    @bind="Post!.CreateDateTime"
    @bind:format="yyyy-MM-dd HH:mm:ss"
    id="CreateDateTime"
    class="form-control"
  />
</div>
<EditForm EditContext="EditContext">
  <DataAnnotationsValidator />
  <ValidationSummary />
  @*<InputNumber @bind-Value="Post!.Id" class="form-control"></InputNumber>*@
  <div class="form-group">
    <label for="title">标题</label>
    <input
      type="text"
      @bind="Post!.Title"
      @bind:event="oninput"
      id="title"
      class="form-control"
    />
  </div>

  <div class="form-group">
    <label for="content">内容</label>
    <InputTextArea
      @bind-Value="Post!.Content"
      id="content"
      class="form-control"
      rows="8"
    ></InputTextArea>
  </div>
  <MyButton
    ButtonType="submit"
    ButtonClass="btn btn-info"
    ButtonName="Submit"
  ></MyButton>
  <MyButton
    ButtonType="reset"
    ButtonClass="btn btn-danger"
    ButtonName="Reset"
  ></MyButton>
</EditForm>

** Quotes: **

1. Employee list blazor component

** Note: The code in this article is refactored through. NET 6 + Visual Studio 2022. You can click on the original link to compare and learn the refactored code. Thank you for reading and support the original author **