StoredProcedure custom sink for Serilog - serilog

Question

I want to call a stored procedure using Serilog. I am aware that there is no such sink so I am creating a custom Sink. I have my logic to call the stored procedure inside the Emit method of the StoredProcedureSink that implements ILogEventSink. Now, this stored procedure returns a value. How can I get this value when I use Log.Information();
class StoredProcedureSink : ILogEventSink
{
private string _connectionString;
public StoredProcedureSink(string connectionString)
{
_connectionString = connectionString;
}
public void Emit(LogEvent logEvent)
{
var conn = new SqlConnection(_connectionString);
conn.Open();
SqlCommand cmd = new SqlCommand(logEvent.MessageTemplate.ToString().Substring(0, logEvent.MessageTemplate.ToString().IndexOf('{')), conn);
cmd.CommandType = CommandType.StoredProcedure;
var properties = logEvent.Properties.GetValueOrDefault("SqlParams");
var json = JObject.Parse(properties.ToString().Substring(properties.ToString().IndexOf('{') - 1));
foreach(var kvp in json)
{
cmd.Parameters.Add(new SqlParameter(kvp.Key, ((JValue)kvp.Value).Value));
}
cmd.ExecuteNonQuery();
//I would like to read the value returned by the stored proc.
}
}
//I have a wrapper DBLogger in which I configure the serilog. I have published DBLogger as a nuget package so I can use it in all my apps.
public class DBLogger()
{
public DBLogger()
{
Log.Logger = new LoggerConfiguration()
.MinimumLevel.Information()
.MinimumLevel.Override("Microsoft", LogEventLevel.Warning)
.Enrich.FromLogContext()
.WriteTo.StoredProcedureSink(
"connectionString")
.CreateLogger();
}
public void Information(string storedProcedureName, T parameters)
{
try
{
Log.Information(storedProcedureName, parameters);
}
catch (Exception ex)
{
Log.Fatal(ex, "Host terminated unexpectedly");
}
}
}
public class Program
{
static void Main()
{
var logger = new DBLogger();
logger.Information("storedProcedureName", params); //need the Id returned by the stored proc here.
}
}

Answer 1

That's not likely to be workable in practice using the normal Serilog model.
The standard processing involves the LogEvent being captured on the main thread, then supplied to each sink in turn - usually asynchronously, and often buffered.
The other concern is that in general, a sink definitely will not be propagating exceptions to the caller either (there is Audit logging, but even that's not intended for this sort of communication).
It seems to me that the sort of auditing you're seeking to accomplish is some distance from Serilog's sweet spot (I may be wrong though - please add some more detail to your question if so).
If you absolutely must do this, you can add an Enricher when logging, which sequesters a callback Action into the LogEvent's Properties, and have that pass it back. Please think long and hard before actually doing that though!

Answer 2

I ended up creating a static variable of StoredProcedureSink class and assigning the return value to that variable. Not sure if this would be the best way to do it.
class StoredProcedureSink : ILogEventSink
{
private string _connectionString;
**public static int returnValue;**
public StoredProcedureSink(string connectionString)
{
_connectionString = connectionString;
}
public void Emit(LogEvent logEvent)
{
var outputParam = new SqlParameter()
{
Direction = ParameterDirection.Output
};
try
{
using (SqlConnection conn = new SqlConnection(_connectionString))
{
using (SqlCommand cmd = new SqlCommand(logEvent.MessageTemplate.ToString().Substring(0, logEvent.MessageTemplate.ToString().IndexOf('{')), conn))
{
conn.Open();
cmd.CommandType = CommandType.StoredProcedure;
var properties = logEvent.Properties.GetValueOrDefault("SqlParams");
var jsonProp = JObject.Parse(properties.ToString().Substring(properties.ToString().IndexOf('{') - 1).Replace(#"\",""));
var lastParam = jsonProp.Last;
foreach (var kvp in jsonProp)
{
if(kvp.Key == lastParam.Path)
{
outputParam.ParameterName = kvp.Key;
outputParam.SqlDbType = SqlDbType.Int;
cmd.Parameters.Add(outputParam);
break;
}
cmd.Parameters.Add(new SqlParameter(kvp.Key, ((JValue)kvp.Value).Value));
}
cmd.ExecuteNonQuery();
}
**returnValue = (int)outputParam.Value;**
}
}
catch(System.Exception e)
{
Debug.WriteLine(e.Message);
}
}
}
public class DBLogger : ILogger
{
public DBLogger()
{
Log.Logger = new LoggerConfiguration()
.MinimumLevel.Information()
.MinimumLevel.Override("Microsoft", LogEventLevel.Warning)
.Enrich.FromLogContext()
.WriteTo.StoredProcedureSink(
"connectionString")
.CreateLogger();
}
~DBLogger()
{
Log.CloseAndFlush();
}
public static IHost CreateHostBuilder(string[] args) =>
new HostBuilder()
.UseSerilog() // <- Add this line
.Build();
public int Information<T>(string storedProcedureName, T parameters)
{
try
{
Log.Information(storedProcedureName, parameters);
}
catch (Exception ex)
{
Log.Fatal(ex, "Host terminated unexpectedly");
}
**return StoredProcedureSink.returnValue;**
}
}