Blazor返回404作为标题

Question

所以我试着用Blazor(而不是WebAssembly(玩了一段时间，但一直使用Redirects和Headers响应。

Post.cs:

public class PostService
{
public List<Post> posts = new List<Post>()
{
new Post { ID = 1, Title = "First title", Text = "first text", Date = DateTime.Now, Author = "JohnDoe", Category = "Good" },
new Post { ID = 2, Title = "Second title", Text = "second text", Date = DateTime.Now, Author = "JohnDoe", Category = "Nice" }
};
public Task<List<Post>> GetPosts()
{
return Task.FromResult(posts);
}
public Task<Post> GetPost(int id)
{
Post post = posts.Where(x => x.ID == id).FirstOrDefault();
return Task.FromResult(post);
}
}

BlogPost.razor:

@page "/post/{ID:int}"
@using ExampleBlog.Data;
@inject PostService PostClassService
@inject NavigationManager _navigationManager
@if (post == null)
{
<p>Loading</p>
}
else
{
@post.Text
}
@code {
[Parameter]
public int ID { get; set; }
public Post post { get; set; }
public bool found { get; set; } = true;
protected override async Task OnInitializedAsync()
{
post = await PostClassService.GetPost(ID);
if (post == null)
{
found = false;
}
}
protected override void OnAfterRender(bool firstRender)
{
if (firstRender)
{
if (!found)
{
_navigationManager.NavigateTo("404");
}
}
}
}

帖子显示，一切都很好。如果ID正确，则显示文本，并在浏览器中正确重定向到404。

问题是服务器标头返回：

curl -i --insecure https://localhost:44332/post/1
HTTP/2 200

它是可以的，工作得很好，但如果我将尝试到达不存在的实体：

curl -i --insecure https://localhost:44332/post/1234
HTTP/2 200

我需要返回404服务器端，这样搜索引擎等才能正确识别所有内容。

Answer 1

它没有返回未找到，因为它实际上正在查找页面路由签名Post(int)。试着在那里设置一个断点。

你需要像这样的东西

public Task<Post> GetPost(int id)
{
Post post = posts.Where(x => x.ID == id).FirstOrDefault();
if (post == null)
{ 
return NotFound();
}
else
{
return Task.FromResult(post);
}
}

Answer 2

所以我发现坏的解决方法，效果很好。

protected override async Task OnInitializedAsync()
{
post = await PostClassService.GetPost(ID);
if (post == null)
{
found = false;
#if !DEBUG
_navigationManager.NavigateTo("404");
#endif
}

#需要调试，因为blazor错误在调试时会引发NavigationManager异常。

并更改Startup.cs 中的端点

app.UseEndpoints(endpoints =>
{
endpoints.MapBlazorHub();
endpoints.MapFallbackToPage("/_Host");
endpoints.MapGet("/404", async context =>
{
context.Response.StatusCode = 404;
await context.Response.WriteAsync("404 not found");
});
});

如果我在发行版中运行它，一切都很好(除了它返回的404未找到的空白页(

curl -i --insecure https://localhost:44332/post/1 
HTTP/2 200
curl -i --insecure https://localhost:44332/post/1234
HTTP/2 302
content-type: text/html; charset=utf-8
location: https://localhost:44332/404