Why do Powerapps connect or preload data sources before data is requested? Issue in Offline Mode.

[IconicAngel]

Hi

I have created a simple test Powerapp to explain the issue I have come across. The test Powerapp has one screen. On that screen, I have a gallery. That gallery is populated by a collection called testData. The testData collection is populated by pressing a button which runs the following code on the OnSelect event:

If(Connection.Connected,Collect(testData,SignIn))

The data source called SignIn points to a Dropbox data source (a table within an Excel Spreadsheet).

When I open the Powerapp I notice that the data loading dots in the top banner of the Powerapp start moving from left to right. This indicates that the Powerapp is either connecting or preloading the SignIn data source. This preload or connection behaviour happens before I press the button to request the SignIn data source. When this Powerapp is opened on a mobile phone which is in flight mode, this preload or connection behaviour causes an error: Failed to load SignIn. An unknown error occurred.

If I remove the OnSelect button code and leave the SignIn data source, this behaviour in flight mode stops occurring i.e. no error message.

My question is: Why does the Powerapp need to connect or preload the SignIn Data Source before I request it using the OnSelect button event? When in Offline mode I would simply disable the button to stop the data from being requested eliminating the possiblity of a user receiving an error message.

[cwebb365]

It's not preloading the data, but it's loading the schema for the collections etc. Usually when buildin Offline app you'll want to have the Offline file load up when not available that way it can read that file for the schema. So you would have If(Connection.Connected,ClearCollect(testData,SingIn);SaveData(testData,"SingInData"),LoadData(testData,"SignInData") 

The offline files are case sensitive so be careful, had that bite me one time pulled my hair out trying to find it on a complete app. 

[IconicAngel]

Thanks for your reply. I'm glad it isn't trying to load data. Is there a way to stop the error message appearing or stop the schema loading. I have a number of data sources and so for a user to recieve three red error messages they may feel the app is broken and stop using it. Most of the users will open it in Offline mode seeing they are in the forest harvesting timber with no cell reception.

[cwebb365]

This is why you need to add in the LoadData on your connected if's into your collections so that they can open it offline. If you don't do that, then it won't work at all and they get errors.

They have to open the app at least once to download data, you can't get past that, it needs the schema, and some data to work with while offine. So you have to plan around that, and when you do open the app online, you upload any cached data changes, download and update your collections to local files and so on.

[IconicAngel]

Thanks for your quick reply. The simple app I presented in my first post only demostrated the issue I was facing. My full app uses ClearCollects and SaveData for the three datasources on start up when Connection.Connected is true. When Connection.Connected is false it use the LoadData option. Even when the data has been Saved locally I still get the error message as it seems that the loading of the schema is a default in Online or Offline. The only thing I can thing of is that you maybe saying to name my local data source the same as the external data source. This way, the Powerapp will think it has the schema and not try to download it every time. I will try this thought out.

[cwebb365]

I meant to make sure your files match between save and load data. You should be loading all your collections on the app start so it’s available to your app.

[IconicAngel]

Hi cwebb365

Thanks for your reply. I do use LoadData to load all my collections on the app start event if the Powerapp is opened where there is no mobile reception. If there is mobile reception, then I load the collections direct from Dropbox and SaveData to update the local versions of the data. The following is my app start code:

/*set variable for if connected*/
Set(ssConnected,false);

/*Test if connected*/
If(Connection.Connected, Set(ssConnected,true);
/*if connected then find the current version number and save it to local data*/
ClearCollect(currentVersionlocal,currentVersionTable); SaveData(currentVersionlocal,"currentVersionStorage");
/* test if the current version number is the same as the currently installed app*/
If("Version: " & First(currentVersionlocal).version=liveVersion.Text,
/* if it is then load worker data and save locally*/
ClearCollect(workers, SignIn); SaveData(workers,"workersLocalStorage")),

/* if we do not have a connection then load the last locally saved version number*/
LoadData(currentVersionlocal,"currentVersionStorage",true);
/* test if the current version number is the same as the currently installed app*/
If("Version: " & First(currentVersionlocal).version=liveVersion.Text,
/*also load the last save workers data*/
LoadData(workers,"workersLocalStorage", true))); 

If("Version: " & First(currentVersionlocal).version=liveVersion.Text,
/*now load previously saved camera setting, todays declarations and unsent reports and declarations*/
LoadData(CameraUsed, "storedCameraUsed", true);
LoadData(reportsList,"savedReportsToSubmit",true);
LoadData(reportsHistory,"savedReportHistory",true);
LoadData(declaration,"savedDeclarationsToSubmit",true);
LoadData(tempDeclaration,"savedDeclarationTemp", true));
/*now start timer to navigate to next screen*/
Set(ssConnected,false); Set(splashScreenTimerOn,true)

With this code, when opening the app on a mobile device which is not connected I receive the following errors:

Once the Powerapp is open in either Online or Offline mode, the Powerapp works as designed. It is only the error messages as per the image that are the issue.

[cwebb365]

Hmmm. Need to check the rest of your app for direct datasource calls, like drop downs. etc. Something is calling these and they need to point to collections that have matching load data at the start to make sure you can fully function offline. Thinking there are a few dependencies out there that you're missing causing these, since a few on this error list don't show in your onstart.

[IconicAngel]

Back to the reason I created a simple Powerapp to test this issue. This simple powerapp has one line of code on the button "Get Data". Nothing on the app start up event. The code is as follows:

If(Connection.Connected,ClearCollect(testData,SignIn); SaveData(testData,"SignIn"),LoadData(testData,"SignIn",true))

The gallery data source = testData

The following screens are when the Powerapp is opened on a mobile devise with internet connection before the "Get Data" button is pressed and then after:

The next two screens are when the Powerapp is opened without an internet connection before and after the "Get Data" button is pressed:

[cwebb365]

On the test, put in a LoadData(testData,"SignIn",true)

You have to load up data so it has the schema etc on load for it to not error. The button can still load over the collection and save new data, but you still have to load the data into your app first.