I'm trying to develop a custom input with Shiny by following this article.
The issue I found is that the subscribe method is not called after the custom input is initialized (that is, find and initializeare called but not subscribe). Here is a minimal example of what I'm trying to do:
app.R
library(shiny)
myModule = function(inputId, initialState) {
tagList(
shiny::singleton(tags$head(
tags$script(src = 'js/binding.js')
)),
tags$div(
tags$input(type = 'checkbox'),
class = 'myModule'
)
)
}
ui <- fluidPage(
fluidRow(
column(12,
myModule("myId", NULL))
)
)
server <- function(input, output) {
}
# Run the application
shinyApp(ui = ui, server = server)
And here is www/js/binding.js:
let binding = new Shiny.InputBinding();
$.extend(binding, {
find: function(scope) {
console.log('find called');
return $(scope).find('.myModule');
},
initialize: function(el) {
console.log('initialize called');
},
subscribe: function(el, callback) {
console.log('subscribe called');
$(el).find('input').change(callback);
},
getValue: function(el) {
console.log('getValue called');
},
});
Shiny.inputBindings.register(binding);
I know only find and initialize are called because these are the only messages that show up in the console when running the app.
If I understand correctly, to be able to talk to the server, the subscribe method is called by the Shiny JS library after the component is registered and the DOM is loaded. I don't know if I'm missing something or if this has to be manually triggered somehow. Any help would be greatly appreciated.