sd_reactive: Create a reactive value that is also stored in survey data

In surveydown: Markdown-Based Programmable Surveys Using 'Quarto' and 'shiny'

Create a reactive value that is also stored in survey data

Description

This function creates a reactive value similar to Shiny's reactive() function, but also automatically stores the calculated value in the survey data.

Usage

sd_reactive(id, expr, blank_na = TRUE)

Arguments

id	Character string. The id (name) of the value to be stored in the data.
expr	An expression that calculates a value based on inputs
blank_na	Logical. If TRUE, NA values are converted to empty strings. Default is TRUE.

Value

A reactive expression that can be called like a function

Examples

# This example shows how sd_reactive would be used in the app.R file
if (interactive()) {
  library(surveydown)
  library(shiny)

  # Demo app setup
  server <- function(input, output, session) {
    # Create a reactive value that is stored in survey data
    product <- sd_reactive("product", {
      as.numeric(input$first_number) * as.numeric(input$second_number)
    })

    # Display the result
    output$result <- renderText({
      paste("The product is:", product())
    })

    # The rest of your survey setup...
    sd_server()
  }

  # In your survey.qmd file, you would use:
  # The product is: `r sd_output("product", type = "value")`
}

surveydown documentation built on Aug. 21, 2025, 6:03 p.m.