mutually dynamic filters for R Shiny Flexdashboard

new_reactive filters flexdashboard

---
title: "reactive test"
output: 
 flexdashboard::flex_dashboard
runtime: shiny
---

```{r}
library(tidyverse)
```



```{r}

candyData <- read.table(
  text = "Brand       Candy
    Nestle      100Grand
    Nestle      Butterfinger
    Nestle      Crunch
    Hershey's   KitKat
    Hershey's   Reeses
    Hershey's   Mounds
    Mars        Snickers
    Mars        Twix
    Mars        M&Ms
    Mars        100Grand
",
  header = TRUE,
  stringsAsFactors = FALSE)



```


Sidebar {.sidebar}
---

```{r}

radioButtons("brand",
               "brand:",
               choices = c("All", unique(candyData$Brand)),
               selected = "All")


radioButtons("candy_name",
               "candy_name:",
               choices = c("All", unique(candyData$Candy)),
               selected = "All")




# this controls the brand options

observe({
  req(input$brand)
  req(input$candy_name)
  
  brand_selection <- input$brand
  candy_selection <- input$candy_name
  candy_rank_value <- 1
  
  if(brand_selection == 'All' & candy_selection == "All"){
    
    cho1 <- c("All", candyData %>% pull(Candy) %>% unique())
    
  } else { if (brand_selection != 'All' & candy_selection == "All") {
    
    cho1 <- c("All", candyData %>% filter(Brand == brand_selection) %>% pull(Candy))
  
  } else { 
    # if (brand_selection == 'All' & candy_selection != "All") {
    
    cho1 <- c("All", candy_selection)
    candy_rank_value <- 2
    
    # }
    }}
  
  updateRadioButtons(session, 
                     "candy_name",
                     "candy:",
                     choices = cho1,
                     selected = cho1[candy_rank_value])
})




observe({
  req(input$candy_name)
  req(input$brand)
  
  candy_selection <- input$candy_name
  brand_selection <- input$brand
  brand_rank_value <- 1
  
  if(candy_selection == 'All' & brand_selection == "All"){
    
    cho2 <- c("All", candyData %>% pull(Brand) %>% unique())
    
  } else { if (candy_selection != 'All' & brand_selection == "All") {
    
    cho2 <- c("All", candyData %>% filter(Candy == candy_selection) %>% pull(Brand))
  
  } else { 
    # if (candy_selection == 'All' & brand_selection != "All") {
    
    cho2 <- c("All", brand_selection)
    brand_rank_value <- 2
    
    # }
    }}
  
  updateRadioButtons(session, 
                     "brand",
                     "brand:",
                     choices = cho2,
                     selected = cho2[brand_rank_value])

})


 ```