如何解决Blazor WebAssembly-在注册服务时将appsettings.json作为依赖项
我试图将我的自定义AppSettings类注册为服务,但无法正常工作,我迷路了。我有位于wwwroot的AppSettings类和相应的appsettings.json文件。然后,我有另一个依赖于AppSettings类的类,看起来像这样:
`<link href="~/lib/bootstrap/dist/css/bootstrap.min.css" rel="stylesheet" />`
`<link href="~/lib/bootstrap3/css/bootstrap.min.css" rel="stylesheet" />`
Main方法如下:
public GeneratorService(AppSettings appSettings)
{
_appSettings = appSettings;
}
我肯定知道JsonSerializer从文件中创建了AppSettings的正确实例。我对此很陌生,但是据我了解,它应该像这样工作:
- 我正在将GeneratorService注入.razor页面,因此该页面要求生成器服务实例
- GeneratorService的ctor中有AppSettings,因此它要求提供AppSettings实例
- 服务提供商知道要获取AppSettings实例,必须调用HttpClient,读取并反序列化appsettings.json文件
但是当我尝试加载提到的.razor页面时,出现此错误:
public static async Task Main(string[] args)
{
var builder = WebAssemblyHostBuilder.CreateDefault(args);
builder.RootComponents.Add<App>("app");
builder.Services.AddScoped(sp => new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });
builder.Services.AddTransient(async sp =>
{
var httpClient = sp.GetRequiredService<HttpClient>();
var response = await httpClient.GetAsync("appsettings.json");
using var json = await response.Content.ReadAsStreamAsync();
return await JsonSerializer.DeserializeAsync<AppSettings>(json);
}
);
builder.Services.AddTransient<GeneratorService>();
await builder.Build().RunAsync();
}
服务提供商为什么无法创建AppSettings并将其注入GeneratorService? 谢谢您的回答。
解决方法
示例appsettings.json
{
"ClientConfigurations": {
"AzureAd": {
"Authority": "https://login.microsoftonline.com/001f3bfc-XXXX-XXXX-XXX-17c0e6de3b0f","ClientId": "815442365ec-xxxx-xxxx-xxxx-1ce9c3f3429","ValidateAuthority": true
}
}
}
添加这些类。注意匹配的名称。
public class LocalConfigurations
{
public ClientConfigurations ClientConfigurations { get; set; }
}
public class ClientConfigurations
{
public AzureAdConfigurations AzureAd { get; set; }
}
public class AzureAdConfigurations
{
public string Authority { get; set; }
public string ClientId { get; set; }
public bool ValidateAuthority { get; set; }
}
在program.cs中,它已经加载到builder.Configuration中。 这两行应该可以帮助您访问它。
var LocalConfigurations = builder.Configuration.Get<LocalConfigurations>();
builder.Services.AddSingleton(LocalConfigurations.ClientConfigurations);
然后使用任何组件
@page "/"
@inject Models.ClientConfigurations config
@config.AzureAd.ClientId
,
我在Blazor中是一个非常新的人,但是如果您在根目录中有一个appsettings.json,例如
{
"message": "Hello word"
}
只需将您的服务IConfiguration注入,
public WeatherForecastClient(HttpClient client,IConfiguration Configuration)
{
Console.WriteLine(Configuration["message"]);
this.client = client;
}
在Dane Vinson's this entry中,您还有另一个方法将其“ appsettings.json”作为嵌入式资源嵌入。
1.-将文件放在Blazor客户端项目的根目录中
2.-编辑您的project.csproj并添加类似的内容
<ItemGroup>
<EmbeddedResource Include="your-file.json">
<CopyToOutputDirectory>Always</CopyToOutputDirectory>
</EmbeddedResource>
</ItemGroup>
3.-创建一个.json和一个类SettingsInfo
4.-在program.cs中,添加服务
public static async Task Main(string[] args)
{
//fileName is NameOf your Assembly.your-file.json,e.g.
string fileName = "Blazor1.Client.appsettings.json";
var stream = Assembly.GetExecutingAssembly()
.GetManifestResourceStream(fileName);
var config = new ConfigurationBuilder()
.AddJsonStream(stream)
.Build();
builder.Services.AddTransient(_ =>
{
return config.GetSection("AppSettings")
.Get<SettingsInfo>();
});
....
}
现在您可以在剃须刀页面或服务中注入SettingsInfo
,谢谢你们的回答。阅读Orak的答案后,我决定将AppSettings实例注册为单例,现在可以正常工作了。所以代替:
builder.Services.AddTransient(async sp =>
{
var httpClient = sp.GetRequiredService<HttpClient>();
var response = await httpClient.GetAsync("appsettings.json");
using var json = await response.Content.ReadAsStreamAsync();
return await JsonSerializer.DeserializeAsync<AppSettings>(json);
}
);
我只是拥有:
var response = await client.GetAsync("appsettings.json");
using var json = await response.Content.ReadAsStreamAsync();
var appSettings = await JsonSerializer.DeserializeAsync<AppSettings>(json);
builder.Services.AddSingleton(appSettings);
我认为将AppSettings作为单例而不是瞬态甚至更有意义。我仍然不确定为什么我的原始代码无法正常工作。
编辑: 使用配置也可以:
var appSettings = builder.Configuration.Get<AppSettings>();
builder.Services.AddSingleton(appSettings.NamesLists);
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