From f535771b21375b9908b93a291892b0440898808b Mon Sep 17 00:00:00 2001
From: Filipe Toscano <filipe.toscano@gmail.com>
Date: Fri, 24 Jan 2025 20:22:32 +0400
Subject: [PATCH] Add payload consideration when using Hangfire

---
 examples/AsyncHangfire/Jobs/EmailSendJob.cs | 29 +++++++++++++++++++++
 examples/AsyncHangfire/README.md            | 23 ++++++++++++----
 2 files changed, 47 insertions(+), 5 deletions(-)

diff --git a/examples/AsyncHangfire/Jobs/EmailSendJob.cs b/examples/AsyncHangfire/Jobs/EmailSendJob.cs
index fe593e4..82c3724 100644
--- a/examples/AsyncHangfire/Jobs/EmailSendJob.cs
+++ b/examples/AsyncHangfire/Jobs/EmailSendJob.cs
@@ -25,6 +25,24 @@ public async Task BackgroundSendAsync( EmailMessage message, CancellationToken c
         _logger.LogDebug( "Email to {To}: {Subject}", message.To, message.Subject );
 
 
+        /*
+         * 
+         */
+        if ( message.Attachments?.Count > 0 )
+        {
+            foreach ( var att in message.Attachments )
+            {
+                if ( att.Path?.StartsWith( "load:" ) == false )
+                    continue;
+
+                _logger.LogDebug( "Attachment: Load {Filename} based on {LoadPath}", att.Filename, att.Path );
+
+                att.Content = await ContentLoadAsync( att.Path!, cancellationToken );
+                att.Path = null;
+            }
+        }
+
+
         /*
          * Send email
          */
@@ -32,4 +50,15 @@ public async Task BackgroundSendAsync( EmailMessage message, CancellationToken c
 
         _logger.LogInformation( "Sent with Id {EmailId}", resp.Content );
     }
+
+
+    /// <summary />
+    private async Task<byte[]> ContentLoadAsync( string attachmentPath, CancellationToken cancellationToken )
+    {
+        await Task.Delay( 1_000, cancellationToken );
+
+        // TODO: Load based on attachmentPath
+
+        throw new NotImplementedException();
+    }
 }
\ No newline at end of file
diff --git a/examples/AsyncHangfire/README.md b/examples/AsyncHangfire/README.md
index fc68089..36c9172 100644
--- a/examples/AsyncHangfire/README.md
+++ b/examples/AsyncHangfire/README.md
@@ -40,14 +40,27 @@ Explained
 |------|-------------------------------------------------------------
 | 1    | When hitting `/test`, the `Get` method of `Controllers/TestController.cs` runs.
 | 2    | `BackgroundJob.Enqueue` will create an instance of the email send job.
-| 3    | When viewing `/jobs`, one job will be enqueued for execution.
-| 4    | Refresh `/jobs`, and the job will change to scheduled.
-| 5    | Refresh `/jobs`, and the job will change to processing.
-
+| 3    | Hangfire server will pick up from queue and invoke `EmailSendJob.BackgroundSendAsync` method.
+| 4    | If an exception is thrown, Hangfire server will retry the job.
+| 5    | Otherwise, job will be marked as Succeeded.
 
 
 Considerations
 ---------------------------------------------------------------------
 
 As per the [best practices](https://docs.hangfire.io/en/latest/best-practices.html) documentation,
-it is advised to keep the 
+it is advised to keep the payload size small.
+
+> Method invocation (i.e. a job) is serialized during the background job
+> creation process. Arguments are converted into JSON strings using the
+> TypeConverter class. If you have complex entities and/or large objects;
+> including arrays, it is better to place them into a database, and then pass
+> only their identities to the background job.
+
+As such, it is desireable to avoid inline attachments, since the
+entire `byte[]` would be stored in the Hangfire job database.
+
+One alternative of setting the value of `Content` property, would be to
+re-use the `Path` property with special value such that the `EmailSendJob`
+can then load the content prior to sending email. See `Jobs/EmailSendJob.cs`
+for a skeleton of such code.