refresh() against sharepoint doesn't update

[DylanEvans]

Hi folks.  I have a powerapp with a O365 sharepoint list backend (maybe 2k records).  I am having trouble keeping it synced and accurate from sharepoint; it also has intermittent ETAG issues. 

In the onvisible of my main screen I populate a variable: 

Refresh('Sharepoint list');
UpdateContext({Current_Comments: Comments_DataCard1.Default});

Then in that screen, there is an html input control and an "add comment" button with the follow onselect code:

If(IsBlank(Comment_Input),Notify("No comment to post",Error),
    Refresh('Sharepoint list');
    UpdateContext({Current_Comments: Concatenate(Office365Users.MyProfile().DisplayName, " ", Text(Now(),ShortDateTime), ": ", Comment_Input.HtmlText, Current_Comments)});
Patch('Sharepoint list', ThisItem, {Comments: Current_Comments});
Reset(Comment_Input); Refresh('Sharepoint list'))

I also have a text box with 

HtmlText = Current_Comments

to show the full history of comments.  

Behavior: If you add a comment with the button, it will instantly update in the text box.  However, if you go to another screen and come back, the text box will revert to the previous comment value.  This confuses me: the onvisible of the main screen should re-pull the most recent, post-patched comment value and push it into the variable, which then should display.  

Waiting does not help - unless you reload the entire app, the new comment will not show up.  I can confirm that the patch successfully committed by checking the sharepoint list - the new comment value is there sometime between 30 seconds and 5 minutes.  

Using the powerapps monitor indicates that a refresh is running much less frequently than I've coded.  Maybe powerapps is cleverly choosing to ignore refreshes in an attempt to make it more performant?

I've also added error handling per this solution around the patch code because my users have reported "lost comments" .  No errors have been seen.  

How can I instruct my powerapp to actually pull the most recent comments value from the sharepoint list?  I think this may also be causing race conditions with a silent discard of the older commit, as concurrent users may be trying to comment back and forth to each other.

[WarrenBelz]

Hi @DylanEvans ,

Breaking this down a bit, this code

If(
   IsBlank(Comment_Input),
   Notify("No comment to post",Error),
   Refresh('Evidence Request');
   UpdateContext(
      {
         Current_Comments: 
         Concatenate(
            Office365Users.MyProfile().DisplayName, 
            " ", 
            Text(Now(),ShortDateTime),
            ": ", 
            Comment_Input.HtmlText, 
            Current_Comments
         )
     }
   );
   Patch(
      'Evidence Request', 
      ThisItem, 
      {Comments: Current_Comments}
   );
   Reset(Comment_Input); 
   Refresh('Evidence Request')
)

Sets a Context Variable Current_Comments by combining a heap of information and the updates a field in the current record in the SharePoint list 'Evidence Request'  (I assume this code is run from within a form or gallery as it refers to ThisItem) with this Variable value. It then refreshes the SharePoint list - all looks good.
Now this bit

Refresh('Sharepoint list');
UpdateContext({Current_Comments: Comments_DataCard1.Default});

Firstly, is this 'Evidence Request' you are refreshing?
The second bit however may be your issue if you simply want to see your current comments - two things here
Are you on a different screen? If so Current_Comments as a Context Variable is actually a different Variable, but more the issue is this bit Comments_DataCard1.Default. Try Comments_DataCard1.Text, however I would suggest a much simpler approach - set a Global Variable

If(
   IsBlank(Comment_Input),
   Notify("No comment to post",Error),
   Refresh('Evidence Request');
   Set(
      Current_Comments,
      Concatenate(
         Office365Users.MyProfile().DisplayName, 
         " ", 
         Text(Now(),ShortDateTime),
         ": ", 
         Comment_Input.HtmlText, 
         Current_Comments
       )
     )
   );
   Patch(
      'Evidence Request', 
      ThisItem, 
      {Comments: Current_Comments}
   );
   Reset(Comment_Input); 
   Refresh('Evidence Request')
)

then don't bother resetting it on the OnVisible - it will be available across all screens. If you don't need to see it, or need ti reset, just use

Set(Current_Comments,Blank())

at the appropriate place.

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[DylanEvans]

Good questions.  All this is happening on the same main screen.  And yes, that is the same sharepoint list - I had incompletely sanitized my references when pasting in the code, and have now edited the original post so that they all match.  

The reason I'm doing this rigmarole with a patch() and context variable is because I don't want the user to set the new text that will be saved to the sharepoint.  The app should take some of their input, add context, then push it into the sharepoint list as an append of what's already there.  Per all the doc I've read, I can't seem to do that with a submitform because you can't set the value of a card through code.

The global variable may cause issues because this main screen is basically an item detail screen, and its value depends on the ThisItem selected.  I would need to reset it to the new ThisItem.Comment.Value every time a new item was selected from the gallery screen.  If my OnVisible refresh isn't getting processed, I'd expect to have the same problems in updating the universal comment variable.  

I mostly don't see why refresh isn't occurring when I ask it to happen - neither in the "Add Comment" button code or in the Onvisible code.  How do I ask Powerapps to go re-pull a sharepoint value on-demand?  

[WarrenBelz]

Thanks @DylanEvans ,

I am not sure I have my mind completely around your logic, however the key points

Patch(
   'Evidence Request', 
   ThisItem, 
   {Comments: Current_Comments}
);
Reset(Comment_Input); 
Refresh('Evidence Request')

writes your comments to the list and then refreshes it - now

UpdateContext({Current_Comments: Comments_DataCard1.Default});

Updates the Variable - with the current value from the list

One issue I mentioned before - why the Default reference? What does CommentsDataCard1.Text get for you?

[DylanEvans]

Good summary of the logic.  

Using CommentValue.Text instead of CommentDatacard.Default yields no change: I replaced every reference, but still have the same issue: after pushing my button (logic: refresh(), updatecontext(), patch(), refresh()), the variable updates correctly, but the CommentValue.Text does not change.  

Likewise, going into another screen and coming back reverts the variable back to the value of CommentValue.Text. 

In neither the Onvisible nor button code are the refreshes working: the CommentValue.Text is not getting updated to the value in the sharepoint list.  It can't be explained by timing, either: it takes about 26 +/- 9 seconds for the new value to show up in the sharepoint list, and going out and back in 10 minutes later will not pull the new comment value.  

[WarrenBelz]

@DylanEvans ,

Very strange what about this
First bit OK

Patch(
   'Evidence Request', 
   ThisItem, 
   {Comments: Current_Comments}
);
Reset(Comment_Input); 
Refresh('Evidence Request')

now this OnVisible

UpdateContext(
   {
      Current_Comments: 
      Lookup(
         'Evidence Request'
         ID=YourGalleryName.Selected.ID,
         Comments
      )
   }
)

You should not have to do this, but it should work.

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[DylanEvans]

Hi Warren - I figured it out.  Well, the problem anyway - not the solution yet.  The problem was that everything in this screen was based on a collection, so was cached.  In the earlier screen (call it ChooseItem), I populate a collection using a filter against the backend sharepoint list.  This main screen is like an Item detail screen that shows different parts of the record and lets actions be taken on it, including commenting on it.  

I just realized/re-read that collections are a local cache of a datasource, so every time I was calling refresh(), it was against the datasource, and the collection was happily unaffected.  I had assumed that a refresh against a datasources would update associated collections as in the style of a database view or a powerbi reference.  No.  
So what I need to do is trigger an update on the collection record after (or maybe also before) each patch().  I tried the following in place of the refresh()s, 

Update(MyCollection,ThisItem,LookUp('Datasource', ID=ThisItem.ID));

but it still doesn't change the CommentValue.Text field in the screen.  I feel like I'm close, though: The second part (clearly based on your last recommendation) does work as a standalone: if I have a text box with 

HTMLText=NewTempComment.Comments

and a "Comment Refresh" button that executes: 

UpdateContext({NewTempComment: LookUp('DataSource', ID=ThisItem.ID)})

pushing the "Comment Refresh" button after adding a comment will make the new text box show the latest comment.  
Why won't the Update() refresh the current record in my collection as promised?

[DylanEvans]

Aright, now I'm really confused: how exactly does Powerapps handle data between collections and datasources?  The form autogenerated in my Item Detail Screen by Powerapps has 

DataSource = [@my_data_source]

 Not 

Datasource = [@My_Collection]

even though I built it off the collection-based gallery.  Is my ItemDetail form referencing the collection or the datasource?  

[WarrenBelz]

Hi @DylanEvans ,

A heap of questions and you have made some correct assumptions, but headed slightly off course on others.

A collection as you correctly stated is a temporary table "cached" (your word) in the app. It is independent of the table and needs to be refreshed either by re-collecting (all the data) or updated with the same information when at the same time as the table. A lot of users update the collection and then when happy all is done, write this to the table. However to your Update - syntax below

UpdateIf(
   MyCollection,
   ThisItem,
   {
      CollectionField1:ValueToUpdate1,
      CollectionField2:ValueToUpdate2
   }
)

Your last question - you have to change the DataSource if you want it to use your collection. Power Apps has no idea what you want to use it for - that is why they are called Canvas Apps.

Please click Accept as solution if my post helped you solve your issue. This will help others find it more readily. It also closes the item. If the content was useful in other ways, please consider giving it Thumbs Up.

[WarrenBelz]

Hi @DylanEvans ,

Just checking if you got the result you were looking for on this thread. Happy to help further if not.

Please click Accept as solution if my post helped you solve your issue. This will help others find it more readily. It also closes the item. If the content was useful in other ways, please consider giving it Thumbs Up.