You must know how to do this before even tackling a conversation app. But here you go.....

Ensure you have a Firestore collection named something like \"conversations\" with the following fields:

userA (String) → Stores User A’s ID

userB (String) → Stores User B’s ID

lastMessage (String) → Stores the last message

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Step 2: Add the Action Flow in FlutterFlow

1. Open the Action Flow Editor

Go to the Button (or any trigger you want to use).

Click + Add Action.

2. Query Firestore to Check if Document Exists

Select \"Firestore Query\" → \"Single Record Query\".

Set the collection to \"conversations\".

Add two filter conditions:

userA is equal to current user ID

userB is equal to selected user ID

Click Confirm.

3. Add a Condition

Click + Add Conditional Action (⚡️ icon).

Click \"+ Add Condition\".

Select \"Does this record exist?\"

Set the condition:

If Record Exists → Update the document.

If Record Does Not Exist → Create a new document.

4. Update the Document (If Exists)

Under the \"True\" branch of the condition:

Click + Add Action.

Choose \"Firestore Update Document\".

Set the Document Reference to the record from the query.

Update the lastMessage field.

5. Create a New Document (If It Doesn’t Exist)

Under the \"False\" branch of the condition:

Click + Add Action.

Choose \"Firestore Create Document\".

Set collection to \"conversations\".

Add fields:

userA → Current User ID

userB → Selected User ID

lastMessage → Message Text

Conditional actions