Reading javascript variable into shiny/R on app load

Question

What I want to do is get the user ID from a wordpress logged-in user when I load a shiny app in an iframe. This variable could then be used to save and modify user-specific

Answer 1

Erik Westlund was kind enough to provide the following solution.

get_user_id.js:

document.domain = "MYDOMAIN.com"; 

var userIDVariableName = parent.userID; 
var userID = document.getElementById("userID"); 
userID.value = userIDVariableName; 

var usernameVariableName = parent.username; 
var username = document.getElementById("username"); 
username.value = usernameVariableName;

As mentioned above remember to change the domain. And set it in the page loading the iframe.

ui.R:

library(shiny) 

shinyUI( bootstrapPage( 

# Hidden input boxes to save the variable to 
HTML(‘ <input type="text" id="userID" name="userID" style="display: none;"> ‘), 
HTML(‘ <input type="text" id="username" name="username" style="display: none;"> ‘), 


# include the js code 
includeScript("get_user_id.js"), 

# Show the output 
textOutput("view") 
))

Change the path to the script as needed.

server.R:

shinyServer(function(input, output, session) { 



userID <- reactive({ input$userID }) 
username <- reactive({ input$username }) 

output$view <- renderText( paste0( "User ID is: ",userID()," and username is: ",username() ) ) 

})

Add this to the page containing the iframe:

PHP to get the variable from wordpress.

<?php global $current_user; 
get_currentuserinfo(); 
$user_name = $current_user->user_login; 
$user_ID = get_current_user_id(); 
?>

And then this to make it a java variable:

<script type="text/javascript"> 
var username = <?php echo json_encode($user_name) ?> ; 
var userID = <?php echo json_encode($user_ID) ?> ; 
</script>

Set domain and the iframe:

<script type="text/javascript"> 
document.domain = "MYDOMAIN.com"; 
</script> 
<iframe id="example1" style="border: none; width: 100%; height: 500px;" src="PATH_TO_SHINY_APP" width="300" height="150" frameborder="0"></iframe>

Answer 2

If you want to call onInputChange as soon as the Shiny app starts then you need to use the following JavaScript code instead of listening for click events.

$(function() {
  setTimeout(function() {
    Shiny.onInputChange("mydata", userID);
  }, 10)
});