如何在Blazor WebAssembly中配置具有不同配置的多个HttpClient实例

Question

我正在尝试在Blazor WASM的Program.cs类中配置多个API URL。我没有在服务器端看到AddHttpClient扩展。想知道是否有人对此有替代解决方案？

这是我到目前为止所拥有的：

CREATE VIEW v_location_averages AS
SELECT
    r.location_id,
    t.name,
    t.eating,
    t.reading,
    t.child_friendly,
    t.pet_friendly,
    t.accessible,
    (COALESCE(t.eating, 0) + COALESCE(t.reading, 0) + COALESCE(t.child_friendly, 0) + COALESCE(t.pet_friendly, 0) + COALESCE(t.accessible, 0)) / num_nonnulls(t.eating, t.reading, t.child_friendly, t.pet_friendly, t.accessible) AS "overall_rating"
FROM (
    SELECT 
        locations.name,
        location_id, 
        AVG(eating) AS "eating",
        AVG(reading) AS "reading",
        AVG(child_friendly) AS "child_friendly",
        AVG(pet_friendly) AS "pet_friendly",
        AVG(accessible) AS "accessible",
    FROM ratings 
    INNER JOIN locations on ratings.location_id = locations.id
    GROUP BY location_id, locations.name
) t
JOIN ratings r ON r.location_id = t.location_id
GROUP BY r.location_id, t.name, t.eating, t.reading, t.child_friendly, t.pet_friendly, t.accessible;

Answer 1

这可以通过Blazor客户端来完成。首先，在您的客户端程序包中，获取以下nuget程序包： Microsoft.Extensions.Http

然后，为该示例创建两个类（通常，您将使用接口，但是单独的类应在此处工作。我将演示正在使用的两个不同的基地址，因此您知道有区别。

>

   public class GoogleService
    {
        private readonly HttpClient httpClient;

        public GoogleService(HttpClient httpClient)
        {
            this.httpClient = httpClient;
        }

        public string GetBaseUrl()
        {
            return httpClient.BaseAddress.ToString();
        }
    }

和Yahoo服务：

  public class YahooService
    {
        private readonly HttpClient httpClient;

        public YahooService(HttpClient httpClient)
        {
            this.httpClient = httpClient;
        }

        public string GetBaseUrl()
        {
            return httpClient.BaseAddress.ToString();
        }
    }

下一步，在客户程序的Program.cs中，您可以执行以下操作：

public static async Task Main(string[] args)
        {
            var builder = WebAssemblyHostBuilder.CreateDefault(args);
            builder.RootComponents.Add<App>("app");

            builder.Services.AddHttpClient<GoogleService>(client =>
            {
                client.BaseAddress = new Uri("https://google.com/");
            });

            builder.Services.AddHttpClient<YahooService>(client =>
            {
                client.BaseAddress = new Uri("https://yahoo.com/");
            });

            await builder.Build().RunAsync();
        }

接下来，您可以像这样将它们注入您的前端，并查看它们确实是两个不同的注入客户端：

@page "/"
@inject BlazorHttpClientTest.Client.Clients.GoogleService googleService;
@inject BlazorHttpClientTest.Client.Clients.YahooService yahooService;

<h1>Hello, world!</h1>

<label>Google Address:</label><label>@googleAddress</label>
<label>Yahoo Address:</label><label>@yahooAddress</label>

@code{
    string googleAddress;
    string yahooAddress;

    protected override void OnInitialized()
    {
        base.OnInitialized();

        googleAddress = googleService.GetBaseUrl();
        yahooAddress = yahooService.GetBaseUrl();

    }
}

就这样，您应该使它工作：

让我知道是否需要我进一步解释其他内容，否则，请标记为已回答，如果它对您有用。