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Simply, I have a Shiny app, where users can select various combinations of values in a data set and produces a graph. However for some of those combinations there is no data and Shiny produces an error message:
Error: 'from' must be length 1
How can I replace this error message with a more informative message, like:
Sorry, there is no data for you requested combination. Please change your input selections
Thanks.
533
You can add content to your Shiny app by placing it inside a *Panel function. For example, the apps above display a character string in each of their panels. The words “sidebar panel” appear in the sidebar panel, because we added the string to the sidebarPanel function, e.g. sidebarPanel("sidebar panel") .
Error sanitization applies to all errors generated within your app: both the ones you yourself produce using stop() , and the ones produced by code you rely on (although, ultimately, some code somewhere will have had to use a stop() or a similar function for an error to occur).
Simply call shinyalert() with the desired arguments, such as a title and text, and a modal will show up. In order to be able to call shinyalert() in a Shiny app, you must first call useShinyalert() anywhere in the app's UI.
But the simplest way to run a Shiny app is to run it locally. You only need the shiny R package installed, and you can run the app in your browser.
You can do this using the validate and need functions. The code would look something like this:
output$MyPlot<-renderPlot({
validate(
need(MyData(), "Sorry, there is no data for you requested combination.
Please change your input selections"
)
)
...code for making plot...
})
If the MyData() part does not exist due to giving an error, than the message will display, otherwise the plot will. Check ?validate for all the details.
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