shinyvalidate (version 0.1.3)

compose_rules: Combine shinyvalidate rule functions

Description

Takes multiple shinyvalidate rule functions, and returns a shinyvalidate rule function. When this resulting rule function is invoked, it will try each of its constituent rule functions in order; the first validation error that is detected will be returned immediately and the remaining rules will not be tried.

This function is not intended to be used by Shiny app authors (i.e. not for InputValidator$add_rule("x", compose_rules(...))), but for developers of reusable shinyvalidate rule functions. See examples.

Usage

compose_rules(...)

Value

A function suitable for use as an InputValidator$add_rule() rule.

Arguments

...

Any number of shinyvalidate rule functions; earlier rules will be attempted before later rules. Argument names are ignored. Single-sided formulas are also accepted instead of a function, using . as the variable name for the input value.

See Also

Other rule functions: sv_between(), sv_email(), sv_equal(), sv_gte(), sv_gt(), sv_in_set(), sv_integer(), sv_lte(), sv_lt(), sv_not_equal(), sv_numeric(), sv_optional(), sv_regex(), sv_required(), sv_url()

Examples

# Create a new shinyvalidate rule that is composed
# of two `sv_*()` rule functions (`sv_integer()` and
# `sv_gt()`, and a custom function for ensuring
# a number is even)
positive_even_integer <- function() {
  compose_rules(
    sv_integer(),
    sv_gt(0),
    ~ if (. %% 2 == 1) "Must be an even number"
  )
}

# Use the `positive_even_integer()` rule function
# to check that a supplied value is an integer, greater
# than zero, and even (in that order)

## Only run examples in interactive R sessions
if (interactive()) {

library(shiny)
library(shinyvalidate)

ui <- fluidPage(
  textInput("value", "Value")
)

server <- function(input, output, session) {
  
  # Validation rules are set in the server, start by
  # making a new instance of an `InputValidator()`
  iv <- InputValidator$new()

  # Add two `add_rule()` statements: one that
  # combines `sv_required()` and `sv_numeric()` in
  # single rule, and another that is defined
  # through the use of `compose_rules()`
  iv$add_rule("value", compose_rules(sv_required(), sv_numeric()))
  iv$add_rule("value", positive_even_integer())

  # Finally, `enable()` the validation rules
  iv$enable()
}

shinyApp(ui, server)

}