Enable/disable selectInput based on value in another selectInput - shiny

Question

In my shiny app, I need to disable selectInput Season and selectInput Mesh if the value selected for selectInput Species is "Kemps". Those same two selectInput objects should be enabled for any other species selection. I found some shinyjs code (https://towardsdatascience.com/heres-how-to-spice-up-your-shiny-app-84866ccb69dd) and adapted to my app but I am getting errors. I would appreciate any guidance. Thanks!
spp <- c("Atlantic Sturgeon","Green","Kemps")
seas <- c("Fall","Winter","Spring","Summer")
mus <- c("A","B","C","D","D1","D2","E")
meshes <- c("Large","Small")
ui <- fluidPage(
titlePanel(title=div(img(src="imgPS.png",height=75),"Protected Species Model")),
sidebarLayout(
sidebarPanel(
selectInput("species", "Protected Species", spp),
selectInput("Season", "Season", seas),
selectInput("MU", "Management Unit", mus),
selectInput("Mesh", "Mesh Size", meshes),
numericInput("trip", "n Trips", 1, min = 1),
actionButton("btnEstTakes","Estimate Takes")
),
mainPanel(
h2("Predicted Takes"),
textOutput("prediction_text")
)
)
)
server <- function(input, output, session) {
observeEvent(input$species, {
if(input$species == "Kemps"){
shinyjs::disable(id = "Season")
shinyjs::disable(id = "Mesh")
}
else {
shinyjs::enable(id = "Season")
shinyjs::enable(id = "Mesh")
}
predict_df <- eventReactive(input$btnEstTakes, {
# Validate the user input. I dont trust these people! :)
validate(need(input$species, "Please select a valid Species!"))
validate(need(input$Season, "Please select a Season!"))
validate(need(input$MU, "Please select a Management Unit!"))
validate(need(input$Mesh, "Please select a Mesh Size!"))
validate(need(input$trip > 0, "Enter a valid trip count!"))
validate(need(input$species != "Atlantic Sturgeon" | (input$MU != "D1" & input$MU != "D2"),
"Management Unit selection not valid for Atlantic Sturgeon"))
validate(need(input$species != "Green" | input$MU != "D",
"Management Unit selection not valid for Green"))
validate(need(input$species != "Kemps" | (input$MU != "D" & input$MU != "D1"),
"Management Unit selection not valid for Kemps"))
ITPYear <- c(2013,2014,2015,2016,2017,2018,2019,2020,2021)
Species <- input$species
Season <- input$Season
MU <- input$MU
Mesh <- input$Mesh
LogEffort <- log(input$trip)
# Create data set for Kemps
df1 <- cbind(MU,LogEffort)
df1 <- as.data.frame(df1)
df1$Species <- Species
df1$MU <- as.factor(df1$MU)
df1$LogEffort <- as.double(df1$LogEffort)
# Create data set for Atlantic Sturgeon and Green
df2 <- cbind(Season,MU,Mesh,LogEffort)
df2 <- as.data.frame(df2)
df2 <- df2[rep(1,9),]
df2 <- cbind(ITPYear,df2)
df2$Species <- Species
df2$ITPYear <- as.factor(df2$ITPYear)
df2$Season <- as.factor(df2$Season)
df2$MU <- as.factor(df2$MU)
df2$Mesh <- as.factor(df2$Mesh)
df2$LogEffort <- as.double(df2$LogEffort)
df3 <- df2
df4 <- cbind(Species,Season,MU,Mesh,LogEffort)
df4 <- as.data.frame(df4)
# Predict based on species selection
if(Species=="Kemps"){
df1$Prediction <- predict(mod.kemps,type="response", newdata=df1)
df1$Live <- round(df1$Prediction * (1-kemps.dead), 0)
df1$Dead <- round(df1$Prediction * (kemps.dead), 0)
} else if(Species=="Green") {
df2$Prediction <- predict(mod.green,type="response",newdata=df2)
pred.use <- mean(df2$Prediction)
df4$Live <- round(pred.use * (1-green.dead), 0)
df4$Dead <- round(pred.use * (green.dead), 0)
} else {
df3$Prediction <- predict(mod.astg,type="response",newdata=df3)
pred.use <- mean(df3$Prediction)
df4$Live <- round(pred.use * (1-astg.dead), 0)
df4$Dead <- round(pred.use * (astg.dead), 0)
}
df.pick <- cbind(Species,Season,MU,Mesh)
df.pick <- as.data.frame(df.pick)
if(Species=="Kemps"){
df.pick$Live <- df1$Live
df.pick$Dead <- df1$Dead
} else {
df.pick$Live <- df4$Live
df.pick$Dead <- df4$Dead
}
df.use <- df.pick[,c('Species','Live', 'Dead')]
return(df.use)
})
df <- reactive({
predict_df()
})
output$prediction_text <- renderText({
paste0("The model predicted ", df()$Live, " live ", df()$Species, " and ", df()$Dead, " dead ", " ", df()$Species, ".")
})
}
shinyApp(ui, server)

Answer 1

Your code works fine if you enable {shinyjs} at beginning of ui:
ui <- fluidPage(
shinyjs::useShinyjs(),
...
(also close with }) the observeEvent)
observeEvent(input$species, {
if(input$species == "Kemps"){
shinyjs::disable(id = "Season")
shinyjs::disable(id = "Mesh")
}
else {
shinyjs::enable(id = "Season")
shinyjs::enable(id = "Mesh")
}
})