Disable dropdown on encondings if no option is available

R/adtteSpec.R

@@ -107,10 +107,14 @@ adtteSpecInput <- function(inputId, # nolint
 
   ns <- NS(inputId)
 
-  selectInput(
-    inputId = ns("paramcd"),
-    label = label_paramcd,
-    choices = ""
+  tagList(
+    selectizeInput(
+      inputId = ns("paramcd"),
+      label = label_paramcd,
+      choices = "",
+      options = list(placeholder = "- Nothing selected -")
+    ),
+    include_js_files("dropdown.js")
   )
 }
 
@@ -295,6 +299,12 @@ adtteSpecServer <- function(id, # nolint
       sort(unique(adtte_joined[[adtte_vars$paramcd]])) # Order should not matter.
     })
 
+    # Start by disabling selection, will be overriden if there are valid choices.
+    session$sendCustomMessage(
+      "toggle_dropdown",
+      list(input_id = session$ns("paramcd"), disabled = TRUE)
+    )
+
     # Once available endpoints change, we update choices (and also the selection
     # if nothing was selected earlier) and warn the user if previous endpoint is
     # not available.
@@ -310,11 +320,15 @@ adtteSpecServer <- function(id, # nolint
         ))
         ""
       }
-      updateSelectInput(
-        session,
+      updateSelectizeInput(
         "paramcd",
         choices = paramcd_choices,
-        selected = new_selected
+        selected = new_selected,
+        session = session
+      )
+      session$sendCustomMessage(
+        "toggle_dropdown",
+        list(input_id = session$ns("paramcd"), disabled = rlang::is_empty(paramcd_choices))
       )
     })
 

R/assaySpec.R

@@ -16,10 +16,16 @@ assaySpecInput <- function(inputId, # nolint
   assert_string(label_assays, min.chars = 1L)
 
   ns <- NS(inputId)
-  selectInput(
-    inputId = ns("name"),
-    label = label_assays,
-    choices = ""
+  tagList(
+    selectizeInput(
+      inputId = ns("name"),
+      label = label_assays,
+      choices = character(0),
+      options = list(
+        placeholder = "- Nothing selected -"
+      )
+    ),
+    include_js_files("dropdown.js")
   )
 }
 
@@ -119,15 +125,18 @@ assaySpecServer <- function(id, # nolint
           hermes::h_short_list(removed_assays), "as per app specifications"
         ))
       }
+      if (length(remaining_assays) == 0) {
+        remaining_assays <- character(0)
+      }
       remaining_assays
     })
 
     observeEvent(choices(), {
       choices <- choices()
-      updateSelectInput(
-        session,
-        "name",
-        choices = choices
+      updateSelectizeInput(session, "name", choices = choices)
+      session$sendCustomMessage(
+        "toggle_dropdown",
+        list(input_id = session$ns("name"), disabled = rlang::is_empty(choices))
       )
     })
 

R/geneSpec.R

@@ -107,6 +107,7 @@ geneSpecInput <- function(inputId, # nolint
         multiple = TRUE,
         selected = 1,
         options = list(
+          placeholder = "- Nothing selected -",
           render = I("{
           option: function(item, escape) {
               return '<div> <span style=\"font-size: inherit;\">' + item.label + '</div>' +

inst/js/dropdown.js

@@ -0,0 +1,26 @@
+// Toggle enable/disable of a dropdown
+//
+// This can be done by `{shinyjs::enable/disable}` R package if that package is
+// added to the dependecies.
+// Parameters
+//  `message` should have `input_id` string and `disabled` logical properties.
+Shiny.addCustomMessageHandler('toggle_dropdown', function(message) {
+  const input_id = message.input_id;
+  const disabled = message.disabled;
+
+  let el = document.getElementById(input_id)
+
+  if (el.selectize !== undefined) {
+    el = el.selectize;
+    if (disabled) {
+      el.lock();
+      el.disable();
+    } else {
+      el.unlock();
+      el.enable();
+    }
+  } else {
+    // Fallback in case selectize is not enabled
+    el.disabled = disabled ? 'disabled' : '';
+  }
+});