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femto-backend/Femto.Docs/Design/MediaUpload/PostMediaClaimFlow.md
john ab2e20f7e1 init
2025-05-03 15:38:57 +02:00

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~~Design Specification: Post Creation with Media Claiming in a Modular Monolith (DDD + MediatR)

1. Overview

This document describes the design of a feature that allows users to upload media files and later attach them to a Post within a modular monolith application. The system is built using Domain-Driven Design (DDD) principles and uses MediatR for in-process communication between modules.

2. Modules Involved

a. Microblogging Module

  • Responsible for Post aggregate lifecycle.
  • Attaches media to posts based on Media IDs.

b. MediaManagement Module

  • Handles file uploads and MediaUpload entity lifecycle.
  • Validates and claims media for Posts.

3. Key Entities

Post (Aggregate Root)

  • Properties: Id, AuthorId, Content, List
  • Methods: AttachMedia(MediaItem), Create(), etc.

MediaItem (Owned Entity)

  • Properties: MediaId, Uri, Type, AltText, Order

MediaUpload (Entity in MediaManagement)

  • Properties: Id, UploaderId, Uri, MimeType, Status (Unassigned, Attached), PostId (nullable)

4. Use Case Flow

Step 1: Upload Media

Command: UploadMediaCommand Handler: UploadMediaHandler (MediaManagement)

  • Validates file and stores it.
  • Creates MediaUpload record with Status = Unassigned.
  • Returns MediaId to client.

Step 2: Create Post

Command: CreatePostCommand Handler: CreatePostHandler (Microblogging)

  • Creates new Post aggregate.
  • For each referenced MediaId:
    • Sends ClaimMediaRequest command via MediatR.

Step 3: Claim Media

Command: ClaimMediaRequest Handler: ClaimMediaHandler (MediaManagement)

  • Validates ownership and existence.
  • Updates Status = Attached, sets PostId.
  • Publishes MediaClaimedEvent.

Step 4: Attach Media to Post

Event: MediaClaimedEvent Handler: MediaClaimedHandler (Microblogging)

  • Loads corresponding Post.
  • Calls post.AttachMedia().
  • Saves updated Post.

5. Event & Command Definitions

UploadMediaCommand

  • FileStream, FileName, MimeType, UploaderId

CreatePostCommand

  • AuthorId, Content, List

ClaimMediaRequest

  • MediaId, AuthorId, PostId

MediaClaimedEvent

  • MediaId, PostId, Uri, Type, AltText

6. Rules and Invariants

  • Only the uploader can claim media.
  • Media can only be claimed once.
  • Posts only accept claimed media.

7. UML Diagrams

UML Diagrams for the described system are provided below.~~