Async Function Fails when called as part of a Constructor - dependency-injection

Question

I'm rather new to Blazor, but I am currently trying to get access to some classes from within a class library that I've created and deployed as a Nuget package. As background, the Nuget package is an Api library, which allows me to talk to a webservice (I don't know if this is relevant or not). However, every time I go to the page where I'm testing, the page never loads and instead I left looking at the browser loading circle until I navigate away or close the application. During my testing here, it seems like it's the #inject call of my interface into the Blazor component which is causing the issue as when I remove it and try to load the page normally, the page does so.
So to demonstrate what I have setup, here is where I've added the Singletons to the DI:
builder.Services.AddSingleton<IApiConfigHelper, ApiConfigHelper>();
builder.Services.AddSingleton<IApiHelper, ApiHelper>();
builder.Services.AddSingleton<ISystemEndpoint, SystemEndpoint>();
Then on the blazor page, I have the following declarations at the top of my page:
#using Library.Endpoints
#using Library.Models
#page "/"
#inject ISystemEndpoint _systemEndpoint
Now I am leaning towards is this something to do with the Nuget package and using it with DI. I have tested the library away from this project (In a console application) and can confirm it's working as it should.
I have also created a local class library as a test to, to see if I could inject a data access class into the page and I can confirm that this works without an issue, which suggests to me that DI is working, just not with my Nuget package.
I did have a look into CORS, given that the Nuget package is accessing an external domain, and setup the following simple CORS policy in the app:
builder.Services.AddCors(policy =>
{
policy.AddPolicy("OpenCorsPolicy", opt =>
opt.AllowAnyOrigin()
.AllowAnyHeader()
.AllowAnyMethod());
});
Which is added to the app after the AddRouting call like so:
app.UseCors("OpenCorsPolicy");
However again, this wasn't the solution so if anyone is able to point me in the right direction with where I may be going wrong with this or offer any advice, I would be most grateful.
EDIT 1 - Provides details #mason queried
Regarding SystemEndpoint, the constructor is being injected with 2 things, as below:
public SystemEndpoint(IApiHelper apiHelper, IOptions<UriConfigModel> uriOptions)
{
_apiHelper = apiHelper;
_uriOptions = uriOptions.Value;
}
My Nuget Library is dependant on the following:
Azure.Identity
Azure.Security.KeyVault.Secrets
Microsoft.AspNet.WebApi.Client
Microsoft.Extensisons.Options.ConfigurationExtensions
EDIT 2 - Doing some further testing with this I have added a simple Endpoint class to my Nuget library, which returns a string with a basic message, as well as returning the values of the 2 UriConfig properties as below. I added this test to 1) sanity check that my DI was working correctly, and 2) check the values that are being assigned from appsettings to my UriConfig Object.
public class TestEndpoint : ITestEndpoint
{
private readonly IOptions<UriConfigModel> _uriConfig;
public TestEndpoint(IOptions<UriConfigModel> uriConfig)
{
_uriConfig = uriConfig;
}
public string TestMethod()
{
return $"You have successfully called the test method\n\n{_uriConfig.Value.Release} / {_uriConfig.Value.Version}";
}
}
However when adding in the dependency of IApiHelper into the Ctor, the method then breaks and fails to load the page. Looking into ApiHeloer, the Ctor has a dependency being injected into it of IApiConfigHelper. Looking at the implementation, the Ctor of ApiConfigHelper is setting up the values and parameters of the HttpClient that should make the REST calls to the external Api.
Now I believe what is breaking the code at this point is a call I'm making to Azure Key Vault, via REST, to pull out the secret values to connect to the Api. The call to KeyVault is being orchestrated via the following method, making use of the Azure.Security.KeyVault.Secrets Nuget Package, however I assume that at the heart of it, it's making a REST call to Azure on my behalf:
private async Task<KeyVaultSecret> GetKeyVaultValue(string secretName = "")
{
try
{
if (_secretClient is not null)
{
var result = await _secretClient.GetSecretAsync(secretName);
return result.Value;
}
}
catch (ArgumentException ae)
{
Console.WriteLine(ae.Message);
}
catch (Azure.RequestFailedException rfe)
{
Console.WriteLine(rfe.Message);
}
return new(secretName, "");
}
So that's where I stand with this at the moment. I still believe it could be down to CORS, as it seems to be falling over when making a call to an external service / domain, but I still can say 100%. As a closing thought, could it be something as simple as when I call call the above method, it's not being awaited????

Answer 1

So after persisting with this it seems like the reason it was failing was down to "awaiting" the call to Azure KeyVault, which was happening indirectly via the constructor of ApiConfigHelper. The resulting method for getting KeyVault value is now:
private KeyVaultSecret GetKeyVaultValue(string secretName = "")
{
try
{
if (_secretClient is not null)
{
var result = _secretClient.GetSecret(secretName);
if (result is not null)
{
return result.Value;
}
}
}
catch (ArgumentException ae)
{
Console.WriteLine(ae.Message);
}
catch (Azure.RequestFailedException rfe)
{
Console.WriteLine(rfe.Message);
}
return new(secretName, "");
}
I am now able to successfully make calls to my library and return values from the Api it interacts with.
I can also confirm that this IS NOT a CORS issue. Once I saw that removing the await was working, I then removed the CORS policy declarations from the service and the app in my Blazor's start-up code and everything continued to work without an issue.
As a final note, I must stress that this is only seems an issue when using the library with Blazor (possibly webApi projects) as I am able to use the library, awaiting the Azure call just fine in a console application.