teal (version 0.16.0)

teal_data_module: Data module for teal applications

Description

Create a teal_data_module object and evaluate code on it with history tracking.

Usage

teal_data_module(ui, server, label = "data module", once = TRUE)
# S4 method for teal_data_module,character
eval_code(object, code)
# S3 method for teal_data_module
within(data, expr, ...)

Value

teal_data_module returns a list of class teal_data_module containing two elements, ui and server provided via arguments.

eval_code returns a teal_data_module object with a delayed evaluation of code when the module is run.

within returns a teal_data_module object with a delayed evaluation of expr when the module is run.

Arguments

ui

(function(id)) shiny module UI function; must only take id argument

server

(function(id)) shiny module server function; must only take id argument; must return reactive expression containing teal_data object

label

(character(1)) Label of the module.

once

(logical(1)) If TRUE, the data module will be shown only once and will disappear after successful data loading. App user will no longer be able to interact with this module anymore. If FALSE, the data module can be reused multiple times. App user will be able to interact and change the data output from the module multiple times.

object

(teal_data_module)

code

(character, language or expression) code to evaluate. It is possible to preserve original formatting of the code by providing a character or an expression being a result of parse(keep.source = TRUE).

data

(teal_data_module) object

expr

(expression) to evaluate. Must be inline code. See within()

...

See Details.

Details

teal_data_module creates a shiny module to interactively supply or modify data in a teal application. The module allows for running any code (creation and some modification) after the app starts or reloads. The body of the server function will be run in the app rather than in the global environment. This means it will be run every time the app starts, so use sparingly.

Pass this module instead of a teal_data object in a call to init(). Note that the server function must always return a teal_data object wrapped in a reactive expression.

See vignette vignette("data-as-shiny-module", package = "teal") for more details.

eval_code evaluates given code in the environment of the teal_data object created by the teal_data_module. The code is added to the @code slot of the teal_data.

within is a convenience function for evaluating inline code inside the environment of a teal_data_module. It accepts only inline expressions (both simple and compound) and allows for injecting values into expr through the ... argument: as name:value pairs are passed to ..., name in expr will be replaced with value.

See Also

teal.data::teal_data, teal.code::qenv()

Examples

tdm <- teal_data_module(
  ui = function(id) {
    ns <- NS(id)
    actionButton(ns("submit"), label = "Load data")
  },
  server = function(id) {
    moduleServer(id, function(input, output, session) {
      eventReactive(input$submit, {
        data <- within(
          teal_data(),
          {
            dataset1 <- iris
            dataset2 <- mtcars
          }
        )

        data
      })
    })
  }
)

eval_code(tdm, "dataset1 <- subset(dataset1, Species == 'virginica')")

within(tdm, dataset1 <- subset(dataset1, Species == "virginica"))

# use additional parameter for expression value substitution.
valid_species <- "versicolor"
within(tdm, dataset1 <- subset(dataset1, Species %in% species), species = valid_species)