PowerApps - Append Text Enabled field Functionality on Sharepoint

In Sharepoint,  we do have "Append Changes to Existing Text" functionality on Mutli text fields. We use this for common requirements like, comments, Audit history logs of the list item / document in a library.  

If we use PowerApps to customize the default form, sad part is, PowerApps doesn't have the capability to display history content of the field. 

Below is the User voice on it and its under review by Microsoft Team.

https://powerusers.microsoft.com/t5/Power-Apps-Ideas/Append-comments-Field/idi-p/35306

We have couple of alternate solutions for this functionality, a few as below,

1. Separate list to store comments and display them in powerapps form by querying them related to the list item
2. Use Flow to query comments from list history and display the response content on PowerApps form
3. Maintain another field in the list to store history of the field content changes and display it on the form.

If the list / process is a new one, I would suggest to go with Approach 3 for now, as its easier to configure and also once the functionality available, we can remove this field from list and form.

Below are the steps to implement it.

Step 1. Create the Multiline text field “Comments” with Plain text enabled, and enable “Append Changes to existing text”, (this is not needed now, but in future, once Powerapps brings the functionality, we can make use of it)

Step 2: Create another Multiline text field, “Comments_History” with rich text enabled.

Step 3: Add comments field in PowerApps form and set visible property to Not(SharePointForm1.Mode = FormMode.View) (Hide this field on view form, as content would be in history field)

Step 4: Add Comments History Field in form and

               4.a: Remove the text field inside data card

               4.b: Insert “HTML Text” from the ribbon and set HTMLText property to Parent.Default

                

               4.c: we would see 2 errors, one is Update property, clear the formula of it

               4.d: Other error is Y property of card, in formula, replace DatacardX with HtmlText1 I, it would resolve

               4.e: Also, for Visible property of data card, set Not(IsBlank(ThisItem.Comments_History)) (We hide this field, when no content in it)

Step 5: Publish the form

Now, we need to have logic to save content from Comments field to the History field. 

Here we can use Patch method from PowerApps or, if we have a Flow functionality on the list, we can write logic in it.  Here, I used Flow, as in below 

Step 6: Now, create a new flow / open existing flow associated to this list, it should trigger on New and Update

Step 7: Add logic to check if comments field is empty or not and if not, build HTML content for Comments history by appending to existing content in History field and update current item

Finally, upon adding item, in the form, it would appear as in below.