CS1929'IHttpClientFactory'不包含'GetFromJsonAsync'的定义

问题描述

在我的Blazor Server项目的Razor组件页面Index.razor中，收到消息“ CS1929-'IHttpClientFactory'不包含'GetFromJsonAsync'的定义”的消息。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的services.AddHttpClient();下添加了行public void ConfigureServices(IServiceCollection services)

错误位于单词httpClientFactory第async Task LoadPeople() => people = await httpClientFactory.GetFromJsonAsync<Person[]>行

我什至尝试将其替换为以下内容，但这只会导致更多错误，因此我将其删除：

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？每次尝试连接http时，每次解决旧问题时，我都会遇到一个新问题。

解决方法

您必须安装System.Net.Http.Json程序包...

为System.Net.Http.HttpClient和System.Net.Http.HttpContent提供扩展方法，这些扩展方法使用System.Text.Json执行自动序列化和反序列化。

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"));

}

在您的FetchData页面中：

@inject HttpClient  httpClient