ConnectingApps.SmartInject 2.0.2

Introduction

SmartInject is a NuGet package to simplify dependency injection in .NET . For example, do you know how to deal with circular depencies? You may want to consider a redesign of your application. However, there is a quicker way. Moreover, do you know how to change your health check to ensure you'll get a detailed json formatted health status instead of just Healthy or Unhealthy? With SmartInject, just a single line of code needs to be changed.

Contents

• Introduction
• Contents
• Lazy Injection
• Health Check Result in Json

Lazy Injection

Assume we have two classes. Instances of these classes need to communicate with each other without knowing each other. You may have experienced this Exception:

System.InvalidOperationException: A circular dependency was detected for the service of type ...

To solve this problem, the code will be like this:

public class Something : ISomething
{
    private readonly Lazy<ISomethingElse> _somethingElse;
    public Something(Lazy<ISomethingElse> somethingElse)
    {
        _somethingElse = somethingElse;
    }
}

and

public class SomethingElse : ISomethingElse
{
    private readonly Lazy<ISomething> _something;
    public SomethingElse(Lazy<ISomething> something)
    {
        _something = something;
    }
}

All you need to do now is to add the collowing line of code to your Program.cs

builder.Services.AddLazySingleton<ISomething, Something>();

Alternatively, you can use AddLazyTransient or AddLazyScoped instead. Do not forget use the following namespace line:

using ConnectingApps.SmartInject;

Health Check Result in Json

When adding a health check to your .NET application, you typically get a result like Healthy after doing a request. The response is not very detailed, which can be a problem when there is something wrong.

However, instead of getting Healthy as a response, you can get a detailed json response instead:

{
    "status": "Healthy",
    "results": {
        "ExampleHealthCheck": {
            "status": "Healthy",
            "description": "Example health check is healthy",
            "data": {
            "exampleDataKey": "exampleDataValue"
            }
        }
    }
}

Achieving this is very simple. Instead of adding a health check like this:

app.MapHealthChecks("/healthz");

you'll add a health check like this:

app.MapHealthChecks("/healthz", new HealthCheckOptions
{
    ResponseWriter = HealthCheckResponseWriters.WriteJsonResponse
});

with this namespace added:

using ConnectingApps.SmartInject;