CS1929 'IHttpClientFactory' 不包含 'GetFromJsonAsync' 的定义

Question

我在 Blazor Server 项目的 Razor 组件页面 Index.razor 上收到消息“CS1929 - 'IHttpClientFactory' 不包含 'GetFromJsonAsync' 的定义”。我正在尝试发出 http 请求以将组件连接到数据库。

下面是index.razor中的代码：

@page "/people"
@inject IHttpClientFactory httpClientFactory

<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 httpClientFactory.GetFromJsonAsync<Person[]>("api/people");
}

然后我在 Startup.cs

中的 public void ConfigureServices(IServiceCollection services) 下添加了行 services.AddHttpClient();

错误在第 httpClientFactory 行 async Task LoadPeople() => people = await httpClientFactory.GetFromJsonAsync<Person[]>

我什至尝试用下面的替换它，但这只会导致更多错误，所以我删除了它：

var http = httpClientFactory.CreateClient();
async Task LoadPeople() => people = await http.GetFromJsonAsync<Person[]("api/people");

解决此问题的最佳方法是什么？每次我在尝试连接 http 时设法修复旧问题时都会遇到新问题。

Answer 1

您必须安装 System.Net.Http.Json 软件包...

Provides extension methods for System.Net.Http.HttpClient and System.Net.Http.HttpContent that perform automatic serialization and deserialization using System.Text.Json.

请在您的 nuget 控制台中执行此操作：

Install-Package System.Net.Http.Json -Version 3.2.1

代码示例：

public void ConfigureServices(IServiceCollection services)
{
   // Chnage the url to yours
    services.AddHttpClient("ServerAPI", client => client.BaseAddress = 
        new Uri("https://localhost:44371/"));

    services.AddTransient(sp => 
           sp.GetRequiredService<IHttpClientFactory> 
           ().CreateClient("ServerAPI"));

}

并且在您的 FetchData 页面中：

@inject HttpClient  httpClient

CS1929 'IHttpClientFactory' 不包含 'GetFromJsonAsync' 的定义

CS1929 'IHttpClientFactory' does not contain a definition for 'GetFromJsonAsync'

c#

crud

blazor

httpclientfactory

blazor-server-side