checkFormArgs: Validates form arguments relative to allowable values

In omegahat/RHTMLForms: Programmatically create R functions corresponding to Web/HTML forms.

Validates form arguments relative to allowable values

Description

This function process the user-specified arguments in a call to an HTML form and verifies that they are acceptable values based on the description of the form elements that were gathered when the form was processed. It checks values that correspond to a text field are within the length constraints. It ensures that values corresponding to a collection of radio buttons, or checkboxes or option menu (select tag) are indeed part of the permissible set of values. It also verifies that values are available for all required elements.

Usage

checkFormArgs(desc, args, all = TRUE, ehandler = errorHandler())

Arguments

desc	an object of class HTMLFormElementsList that is a collection of the HTMLFormElement objects describing each of the form objects. This should not include the Reset or Submit elements.
args	the named list of arguments provided by the user in the call. The names should correspond to the names of the elements in desc. The values are compared to the accetpable values using the generic function validateValue.
all	a logical value indicating whether, if TRUE, to process all the values regardless if errors are encountered and to report all the errors at the end. Alternatively, if FALSE we terminate the validation with an error when the first error is encountered.
ehandler	a function that is called, if all is TRUE, each time there is an invalid value for a form element. This allows the caller to control how errors are handled.

Details

This uses the generic function validateValue to compare the user-specified value against the acceptable values described the form element description using a method suitable for that element type, e.g. HTMLSelectElement or HTMLTextAreaElement.

Author(s)

Duncan Temple Lang <[e-mail]>

See Also

validateValue formQuery

Examples

## Not run: 
if(require(XML)) {
 u = system.file("testInputs", "dump.html", package = "odbAccess")
 
# formElements = htmlTreeParse(u, handlers = formElementHandlers(u, FALSE))$value()$elements
 form = getHTMLFormDescription(u, handlers = formElementHandlers(u, FALSE))

 args = 
  list(
   species="elegans",
   upload="",
   list="",
   flank3="0",
   flank5="0",
   feature="Gene Models",
   dump = "Plain TEXT",
   orientation = "Relative to feature",
   relative = "Chromosome",
   DNA ="flanking sequences only"
  )

 checkFormArgs(form, args)

   # This should fail.
 args$dump = "Foo"
 try(checkFormArgs(formElements, args))

  # Fail because the feature is from the wrong set.
 args$species = "briggsae"
 try(checkFormArgs(form, args))




 args$species = "briggsae"
 try(checkFormArgs(formElements, args))



 f = getHTMLFormDescription(system.file("testInputs", "SpeakEasy.html", package = "odbAccess"))

  # Fails because of box3.
 try(checkFormArgs(f, list("some_text" = "Duncan", box="box3", choice="He", radbut="oops")))

  # 2 values for radbut
 try(checkFormArgs(f$elements, list("some_text" = "Duncan", box="box1", choice="He", radbut=c("eep", "oop"))))

   # some_text String too long.
 try(checkFormArgs(f, list("some_text" = paste(rep("A", 60), collapse=""), box="box1", choice="He", radbut=c("eep", "oop"))))

  # Argument name d doesn't match.
 try(checkFormArgs(f, list("some_text" = "Duncan", box="box1", choice="He", d=c("eep", "oop"))))
}

## End(Not run)

omegahat/RHTMLForms documentation built on Nov. 29, 2023, 12:36 a.m.