rspec/rules/S6421/csharp/rule.adoc

== Why is this an issue?

The top-most level of an Azure Function code should include a try/catch block to capture and log all errors so you can monitor the health of the application effectively.
In case a retry policy has been defined for your Azure Function, you should rethrow any errors that should result in a retry.

// If you want to factorize the description uncomment the following line and create the file.
//include::../description.adoc[]

=== Noncompliant code example

[source,csharp]
----
[FunctionName("HttpExample")]
public static async Task<IActionResult> Run(
    [HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = null)] HttpRequest req)
{
    // Noncompliant
    string requestBody = await new StreamReader(req.Body).ReadToEndAsync();
    dynamic data = JsonConvert.DeserializeObject(requestBody);
    // do stuff
}
----

=== Compliant solution

[source,csharp]
----
[FunctionName("HttpExample")]
public static async Task<IActionResult> Run(
    [HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = null)] HttpRequest req)
{
    try
    {
        string requestBody = await new StreamReader(req.Body).ReadToEndAsync();
        dynamic data = JsonConvert.DeserializeObject(requestBody);
        // do stuff
    }
    catch (Exception ex)
    {
        // do stuff
    }
}
----

== Resources

* https://docs.microsoft.com/en-us/azure/azure-functions/functions-bindings-error-pages?tabs=csharp[Azure Functions error handling and retries]
* https://docs.microsoft.com/en-us/azure/azure-functions/functions-bindings-error-pages?tabs=csharp#retry-policies-preview[Azure Functions retry policies]