How can I use str_detect inside a conditionalPanel in Shiny?

Question

I have a Shiny App where I want a conditionalPanel to appear every time the user selects a string containing a specific word, but not the exact word, in a previous selectInput. Here is what I currently have:

library(shiny)
library(tidyverse)

ui <- fluidPage(
  sidebarPanel(
    selectInput("input1",
                "Select a word:",
                 choices = c("Word1 something",
                             "Word2 something",
                             "Word3 something",
                             "Word4 something",
                             "Word1 nothing")
               )
              )
             )

server <- function(input, output){}

shinyApp(ui, server)

If I could use simple R code inside of the conditionalPanel, it would look like this:

ui <- fluidPage(
  sidebarPanel(
    selectInput("input1",
                "Select a word:",
                 choices = c("Word1 something",
                             "Word2 something",
                             "Word3 something",
                             "Word4 something",
                             "Word1 nothing")),
    conditionalPanel(
      condition = str_detect(input1, "Word1"),
      selectInput("input2", 
                  "Select another word:",
                  choices = c("Word10",
                              "Word11")))
              )
             )

server <- function(input, output){}

shinyApp(ui, server)

However, conditionalPanel requires javascript code as a condition. If I wanted the exact word, I would use "input.input1 == 'Word1 nothing'" but that's not what I'm looking for. Anyone knows how I can do this?

Thanks in advance!

Answer 1

Following up on my comment, here's an alternative way -

library(shiny)
library(stringr)

ui <- fluidPage(
  sidebarPanel(
    selectInput("input1",
                "Select a word:",
                 choices = c("Word1 something",
                             "Word2 something",
                             "Word3 something",
                             "Word4 something",
                             "Word1 nothing")),
    uiOutput("cond_input")
              )
             )

server <- function(input, output, session) ({
  output$cond_input <- renderUI({
      req(str_detect(input$input1, "Word1"))
      selectInput("input2", 
                  "Select another word:",
                  choices = c("Word10",
                              "Word11"))
  })
})

shinyApp(ui, server)

Answer 2

You can use indexOf() javascript method which returns the position of the first occurrence of a specified value in a string. It returns -1 if the value to search for never occurs.

library(shiny)

ui <- fluidPage(
  sidebarPanel(
    selectInput("input1",
                "Select a word:",
                choices = c("Word1 something",
                            "Word2 something",
                            "Word3 something",
                            "Word4 something",
                            "Word1 nothing")),
    conditionalPanel("input.input1.indexOf('Word1') > -1",
                     selectInput("input2", 
                                 "Select another word:",
                                 choices = c("Word10",
                                             "Word11"))
    )
  )
)

server <- function(input, output, session) ({
})

shinyApp(ui, server)