使用非静态触发器创建IFunctionProvider
使用非静态触发器创建IFunctionProvider
提问于 2021-09-29 06:03:34
我有一个Azure函数的IFunctionProvider实现，它为/healthcheck创建了一个路由。函数元数据的入口点是一个名为Somenamespace.TestTrigger.RenderHealthCheck的方法。我的代码如下所示：
public class TestTrigger
{
public static async Task<IActionResult> RenderHealthCheck(HttpRequest req)
{
return new OkObjectResult("OK");
}
}
public class HealthCheckTrigger : IFunctionProvider
{
public ImmutableDictionary<string, ImmutableArray<string>> FunctionErrors { get; }
public async Task<ImmutableArray<FunctionMetadata>> GetFunctionMetadataAsync()
{
var assembly = Assembly.GetExecutingAssembly();
var functionMetadata = new FunctionMetadata()
{
Name = nameof(TestTrigger.RenderHealthCheck),
FunctionDirectory = null,
ScriptFile = $"assembly:{assembly.FullName}",
EntryPoint = $"{typeof(TestTrigger).FullName}.{nameof(TestTrigger.RenderHealthCheck)}",
Language = "DotNetAssembly"
};
var jo = JObject.FromObject(new HttpBindingMetadata()
{
Methods = new List<string> { HttpMethods.Get },
Route = "HealthCheck",
AuthLevel = AuthorizationLevel.Anonymous,
});
var binding = BindingMetadata.Create(jo);
functionMetadata.Bindings.Add(binding);
var functionMetadataList = new List<FunctionMetadata>
{
functionMetadata
};
return await Task.FromResult(functionMetadataList.ToImmutableArray()).ConfigureAwait(false);
}
}这很好，当我运行这个函数并命中/HealthCheck端点时，我会得到我的OK消息。但是，我想使RenderHealthCheck方法是非静态的，这样我就可以在构造函数中使用依赖项注入，并在我的应用程序中访问各种服务。我把我的代码改为：
public class TestTrigger
{
private readonly HealthCheckService healthCheckService;
public TestTrigger(HealthCheckService healthCheckService)
{
this.healthCheckService = healthCheckService;
}
public async Task<IActionResult> RenderHealthCheck(HttpRequest req)
{
return new OkObjectResult("OK");
}
}现在，当我到达端点时，会得到以下异常：
Executed 'Functions.RenderHealthCheck' (Failed, Id=c02a9ba6-1ed3-4c07-8b38-214d345b6ff1, Duration=488ms)
Microsoft.Azure.WebJobs.Host.FunctionInvocationException: Exception while executing function: Functions.RenderHealthCheck
---> System.NullReferenceException: Object reference not set to an instance of an object.
at lambda_method(Closure , TestTrigger , Object[] )
at Microsoft.Azure.WebJobs.Host.Executors.TaskMethodInvoker`2.InvokeAsync(TReflected instance, Object[] arguments) in C:\projects\azure-webjobs-sdk-rqm4t\src\Microsoft.Azure.WebJobs.Host\Executors\TaskMethodInvoker.cs:line 21
at Microsoft.Azure.WebJobs.Script.Description.DotNetFunctionInvoker.MethodInvoker`2.InvokeAsync(Object target, Object[] parameters) in D:\a\1\s\src\WebJobs.Script\Description\DotNet\DotNetFunctionInvoker.cs:line 533
at Microsoft.Azure.WebJobs.Script.Description.DotNetFunctionInvoker.InvokeCore(Object[] parameters, FunctionInvocationContext context) in D:\a\1\s\src\WebJobs.Script\Description\DotNet\DotNetFunctionInvoker.cs:line 272
at Microsoft.Azure.WebJobs.Script.Description.FunctionInvokerBase.Invoke(Object[] parameters) in D:\a\1\s\src\WebJobs.Script\Description\FunctionInvokerBase.cs:line 82
at Microsoft.Azure.WebJobs.Script.Description.FunctionGenerator.Coerce[T](Task`1 src) in D:\a\1\s\src\WebJobs.Script\Description\FunctionGenerator.cs:line 225
at Microsoft.Azure.WebJobs.Host.Executors.FunctionInvoker`2.InvokeAsync(Object instance, Object[] arguments) in C:\projects\azure-webjobs-sdk-rqm4t\src\Microsoft.Azure.WebJobs.Host\Executors\FunctionInvoker.cs:line 52
at Microsoft.Azure.WebJobs.Host.Executors.FunctionExecutor.InvokeWithTimeoutAsync(IFunctionInvoker invoker, ParameterHelper parameterHelper, CancellationTokenSource timeoutTokenSource, CancellationTokenSource functionCancellationTokenSource, Boolean thro
wOnTimeout, TimeSpan timerInterval, IFunctionInstance instance) in C:\projects\azure-webjobs-sdk-rqm4t\src\Microsoft.Azure.WebJobs.Host\Executors\FunctionExecutor.cs:line 555
at Microsoft.Azure.WebJobs.Host.Executors.FunctionExecutor.ExecuteWithWatchersAsync(IFunctionInstanceEx instance, ParameterHelper parameterHelper, ILogger logger, CancellationTokenSource functionCancellationTokenSource) in C:\projects\azure-webjobs-sdk-r
qm4t\src\Microsoft.Azure.WebJobs.Host\Executors\FunctionExecutor.cs:line 503
at Microsoft.Azure.WebJobs.Host.Executors.FunctionExecutor.ExecuteWithLoggingAsync(IFunctionInstanceEx instance, FunctionStartedMessage message, FunctionInstanceLogEntry instanceLogEntry, ParameterHelper parameterHelper, ILogger logger, CancellationToken
cancellationToken) in C:\projects\azure-webjobs-sdk-rqm4t\src\Microsoft.Azure.WebJobs.Host\Executors\FunctionExecutor.cs:line 281
--- End of inner exception stack trace --我没有在FunctionMetadata或HttpBindingMetadata中看到任何似乎控制入口点是否是静态的东西。实例方法根本不受支持吗？如果不是的话，似乎是一个巨大的限制。在IFunctionProvider上基本上没有任何类型的文档，所以不太确定从哪里开始。任何帮助都将不胜感激！
Stack Overflow用户
发布于 2022-04-04 20:55:38
如果您确实希望能够将HealthCheckService注入静态函数，则可以为其创建自定义绑定并从FunctionExecutionContext解析服务。
基于https://microsoft.github.io/AzureTipsAndTricks/blog/tip247.html，我能够完成以下工作：
[assembly: WebJobsStartup(typeof(HealthBindingStartup))]
[Binding]
[AttributeUsage(AttributeTargets.Parameter)]
public class HealthAttribute : Attribute
{
}
[Extension(nameof(HealthBinding))]
public class HealthBinding : IExtensionConfigProvider
{
public void Initialize(ExtensionConfigContext context)
{
var rule = context.AddBindingRule<HealthAttribute>();
rule.BindToInput((HealthAttribute attr, ValueBindingContext context) =>
{
var service = context.FunctionContext.CreateObjectInstance<HealthCheckService>();
return Task.FromResult(service);
});
}
}
public static class HealthBindingExtension
{
public static IWebJobsBuilder AddHealthBinding(this IWebJobsBuilder builder)
{
if (builder == null)
{
throw new ArgumentNullException(nameof(builder));
}
builder.AddExtension<HealthBinding>();
return builder;
}
}
public class HealthBindingStartup : IWebJobsStartup
{
public void Configure(IWebJobsBuilder builder)
{
builder.AddHealthBinding();
}
}这样，您就可以更新您的函数并添加[Health] HealthCheckService service，并让这个绑定注入您想要的服务。
此绑定的元数据是：
{ "name": "service", "type": "health", "direction": "in" }这是通过IFunctionProvider添加函数时所需要的，它忽略了任何属性。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/69371155
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