How to build a forum conversation feature in Bubble

A simple and reliable way to build a forum conversation in Bubble is to create two data types (Thread and Post), display a repeating group of Threads, and when a user opens one, show another repeating group of Posts filtered by that Thread. You allow users to create new Threads and Posts with standard Create a new thing actions, and you protect everything with proper Privacy Rules so only logged‑in users can post. That’s the basic structure every Bubble forum uses and it scales well.

Data Structure

You only need two data types:

• Thread: title (text), creator (User), posts (list of Post)
• Post: body (text), author (User), thread (Thread), created date (auto)

The key link is that each Post stores which Thread it belongs to. Bubble can auto-display lists without you manually managing the Thread’s list of posts.

UI Layout

You create:

• A page showing a repeating group of Threads.
• A button “Create Thread” that opens a group or popup with an input for the title.
• A page (or reusable) for viewing a single Thread. On this page you place a repeating group with Type of content = Post and Data source = Search for Posts with constraint thread = Current Page Thread.
• A multiline input for adding a Post and a button “Send”.

Workflows

Example: creating a new Thread.

// Workflow: When Create Thread button is clicked
Create a new Thread:
  title = Input Thread Title's value
  creator = Current User

Example: creating a Post inside a Thread.

// Workflow: When Send button is clicked
Create a new Post:
  body = MultilineInput Post Body's value
  author = Current User
  thread = Current Page Thread

Privacy Rules

For both Thread and Post data types:

• Allow Logged in users to create new things.
• Allow Everyone to read basic fields like title or body if your forum is public.
• Do not expose author emails or anything sensitive.

This prevents anonymous posting while keeping content visible.

Sorting & UX Improvements

• Sort Threads by Modified Date descending to bubble up the most recent conversations.
• Sort Posts by Created Date ascending so conversations read naturally.
• Use a Scroll to entry action after creating a Post to jump to the newest message.