[SOLVED] Using a input variable as a numeric and string on a Shiny APP

Using a input variable as a numeric and string on a Shiny APP

So, i created a program to optimize my marketing budget. As an input, the user need to set the total budget. I create this input variable as "cust_tot" in the Shiny UI code below:

ui <- fluidPage(
  titlePanel("Budget Optimizer"),
  sidebarLayout(
    sidebarPanel(
      numericInput("custo_tot", "Valor total do Investimento:", value = 3243452, min = 0),
      actionButton("submit", "Otimizar")
    ),
    mainPanel(
      plotOutput("grafico_investimento_atual")
    )
  )
)

In order to get the data, i need to query, but the variable "custo_tot" (inputed by the user) is also going to be part of the query:

in my original code, it was something like that:

sql <- " query here " 
sql = gsub("custo_rest_min_aux", custo_rest_min_aux, sql)
sql = gsub("custo_rest_max_aux", custo_rest_max_aux, sql)
sql = gsub("month_rest", sQuote(month_rest), sql)
sql = gsub("custo_tot", input$custo_tot, sql)
  
tb <- bq_project_query(projectid, sql)
df = bq_table_download(tb) %>% data.frame()

But i know that i cant simply use input$custo_tot because it shows the following error message:

Error in input$custo_tot : 
  Can't access reactive value 'custo_tot' outside of reactive consumer.
ℹ Do you need to wrap inside reactive() or observe()?

how should i deal with this?

Solution

As the error specifies, you cannot access the input list unless you are inside a reactive consumer:

server <- function(input, output, session) {
  sql <- reactive({
    sql <- " query here " 
    sql = gsub("custo_rest_min_aux", custo_rest_min_aux, sql)
    sql = gsub("custo_rest_max_aux", custo_rest_max_aux, sql)
    sql = gsub("month_rest", sQuote(month_rest), sql)
    sql = gsub("custo_tot", input$custo_tot, sql)
    sql
  })
  
}

This will make it a reactive so any time the inputs are updated this reactive will lazily update. Remember to use this reactive you need to call it like: sql().