updating/initializing context variable on app start

[Tono_Analyst]

Hi!

Context

I have a gallery that is filtered by a context variable 'table_ID' and a dropdown box that updates 'table_ID' on change. UpdateContext({table_ID: ...}). The table_ID variable updates correctly on change and filters the gallery correctly.

Problem

The issue I am having is that when the app starts, nothing is assigned to 'table_ID' and hence the gallery is blank.

I have tried updating the context of 'table_ID':

•  when the screen is 'On Visisble', however this only works if I transition to the screen - as opposed to when the app starts.
• 'On App Start', however, this did not update the context of the variable. 

I am not sure how to initialize the context variable 'table_ID' based on the default value that exists within the dropbox. I am not sure what the flow/process order of Power Apps is, but is it possible that it is executing the update context command before the value has loaded into the dropbox (dropbox content is based on a lookup)?

A workaround I can think of is to have a 'menu screen' that navigates to the screen with the variable which would correctly trigger the 'on visible update context' command. However, ideally I would like to initialize the context and go straight to the screen. 

Thank you for any help in advance!

[StalinPonnusamy]

Hi @Tono_Analyst 

UpdateContext creates a local variable, so this can be used within a single screen. On the other hand, SET is the global variable and that can be used throughout the application.

UpdateContext - Local Variable

Set - Global Variable

So if you are looking 'table_ID' for multiple screens then use

Set(table_ID, SomeValue)

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[Tono_Analyst]

Thank you @StalinPonnusamy  for your response. The variable is only relevant for the first screen, hence why I used a local variable. 

Is there a way to update/initialize the local variable for the first screen when the app launches? As I mentioned in my previous post, 'on start'(app) and 'on visible'(screen) did not work for updating the context of the variable.

Essentially, I want to define the local variable on the first screen that is opened when the app is launched.

[StalinPonnusamy]

Hi @Tono_Analyst,

App and the first screen having separate contexts. So there is no way to define it.

But I'm looking at your requirement, We should display the gallery even no id is selected. For example

Gallary Items Property should like this

If(!IsBlank(Table_Id), ColFilteredData, MainDataSource)

Here is my code that was implemented on a similar case

[Tono_Analyst]

Thank you again, this is close to what I want to achieve.

However, instead of displaying the entire gallery if the Table_ID is blank, I would like to update the local variable table_ID.

I basically never want Table_ID to be blank, as there will always be values in the dropbox to filter. It seems like this may not be possible. Perhaps I can use a global variable and set it on start based on the values within the dropbox? Although I am not sure if the dropbox values will be defined at that point for the set function to refer to...

[StalinPonnusamy · Accepted solution]

Hi @Tono_Analyst 

There is no option to get dropdown value on screen 1 from App start. But we can do another approach which is to add a filter. In my case customerkey never be 0, so this returns an empty.

Example

If(!IsBlank(FilteredApplied) && FilteredApplied, ColFilteredData, Filter(DimCustomer, CustomerKey=0))

I hope this solves the problem