Validation of user input

[StefanMunnes]

Description

I think it would be helpful if one could define some checks for the input and give a note if it doesn't match the expectations. I saw there are some packages out there, but just tested shinyvalidate . I will stick to the important example of valid e-mail address input. For now, I was able to implement the following code in the APP.R server function:

  iv <- InputValidator$new()
  iv$add_rule("mail", sv_email("No valid email address."))
  iv$add_rule("mail, sv_regex("^.+?@.+?\..{2,}$", "No valid email address.")) # general alternative
  iv$enable()

This package offers much more helper functions (e.g. sv_equal or sv_between) and the error messages fit quite well in the output. I was wondering if you are interested in implementing this functionality in your code logic. I think there are two reasonable options.

1. add the validation logic (regex or %in% or between(), etc.) directly in SURVEY.R as an argument:

sd_question(
  type = "text",
  id = "mail",
  label = "Please provide your email adress:",
  validate = c(
    "No valid email address." = "^.+?@.+?\..{2,}$"
  )

or 2. add a new helper function similar to sd_skip_if() in the APP.R server function:

sd_validate(
  !grepl("^.+?@.+?\..{2,}$", input$mail) ~ "No valid email address"
)

One additional point I wasn't able to solve with the shinyvalidate package, but what could be helpful in a new implementation, the comparison of the values from two inputs. For example, if you let the respondents input their email address twice:

1. version in SURVEY.R:

sd_question(
  type = "text",
  id = "mail2",
  label = "Please provide your email adress:",
  validate = c(
    "email addresses are not the same" = mail != mail2
  )

or 2. version APP.R server function:

sd_validate(
  input$mail != input$mail2 ~ "email addresses are not the same" # but unclear, where to output this error message
)

[jhelvy]

Cool, yes input validation is on our roadmap. I like the suggestion of adding a sd_validate() function to add validation conditions. We'll look into this.