我应该使用什么类型的IHttpClientFactory方法将HttpClient添加到服务器端Blazor

Question

我用Blazor和Entity Framework Core制作了一个Blazor Make a CRUD应用程序，但我收到了以下错误消息：

错误消息

以下是我的Razor组件中的代码：

@page "/people"
@inject HttpClient http
<h3>People</h3>
@if (people == null)
{<text>Loading...</text>}
else if (people.Length == 0)
{ <text>No people have been added to this database.</text>}
else
{
<table>
<thead>
<tr>
<th>ID</th>
<th>Title</th>
<th>First Name</th>
<th>Last Name</th>
<th>Phone Number</th>
<th>Email ID</th>
<th>Address</th>
</tr>
</thead>
<tbody>
@foreach (var person in people)
{
<tr>
<td><a>Edit</a><button>Delete</button></td>
<td>@person.ID</td>
<td>@person.Title</td>
<td>@person.FirstName</td>
<td>@person.LastName</td>
<td>@person.PhoneNumber</td>
<td>@person.Email</td>
<td>@person.Address</td>
</tr>
}
</tbody>
</table>
}
@code {
Person[] people { get; set; }
protected override async Task OnInitializedAsync()
{
await LoadPeople();
}
async Task LoadPeople() => people = await http.GetFromJsonAsync<Person[]>("api/people");
}

下面是Startup.cs:中的代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Components;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using CuriousDriveTutorial.Data;
using Microsoft.Extensions.Options;
using Microsoft.EntityFrameworkCore;
namespace CuriousDriveTutorial
{
public class Startup
{
public Startup(IConfiguration configuration)
{
Configuration = configuration;
}
public IConfiguration Configuration { get; }
// This method gets called by the runtime. Use this method to add services to the container.
// For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
public void ConfigureServices(IServiceCollection services)
{
services.AddDbContext<ApplicationDBContext>(Options => Options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));
//services.AddHttpClient();
services.AddRazorPages();
services.AddServerSideBlazor();
services.AddSingleton<WeatherForecastService>();
}
// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
else
{
app.UseExceptionHandler("/Error");
// The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
app.UseHsts();
}
app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();
app.UseEndpoints(endpoints =>
{
endpoints.MapBlazorHub();
endpoints.MapFallbackToPage("/_Host");
});
}
}
}

我试着添加services.AddHttpClient();，但没有什么不同，所以我删除了它。

我读到我需要使用IHttpClientFactory为服务器端Blazor发出HTTP请求，所以我找到了以下链接：

https://learn.microsoft.com/en-us/aspnet/core/fundamentals/http-requests?view=aspnetcore-3.1#基本用法

然而，我不确定我是否应该使用"基本用途"、"命名客户端"、"键入客户端"或"生成客户端"的方法。那么，对于这种类型的项目，哪种方法是最好的呢？

提前谢谢。

附言：我是后端新手。

Answer 1

您缺少服务配置。只需将其添加到您的Startup类中即可

public void ConfigureServices(IServiceCollection services)
{
...
services.AddHttpClient();
}