# Custom Server-Side Validator Element

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## Table of Contents

- 1 Custom Server-Side Validator - #custom {}

## 1 Custom Server-Side Validator - #custom {}

Attach a custom validator, written in Erlang, to an element. The validator will be executed on the server during a postback.

### Usage

    % Function to validate that a value is either upper or lower case,
    % depending on the value of Tag...
    F = fun(Tag, Value) ->
      case Tag of
        upper -> string:to_upper(Value) == Value;
        lower -> string:to_upper(Value) == Value
      end
    end,

    % Wire the validator in upper case mode...
    wf:wire(ButtonID, TextBoxID, #validate { validators=[
      #custom { text="Must be uppercase", function=F, tag=upper }
    ]})

### Attributes

text - (string)
  The text to display if validation fails.
function - (fun)
  An Erlang function that returns true if the value is valid, false if invalid. <br>fun(Tag, Value) -> 'true' or 'false'
tag - (Erlang term)
  Tag value is passed into the custom validation function.

Date: 2012-10-18 03:23:22 CDT

Author: Rusty Klophaus (@rustyio)

Org version 7.8.02 with Emacs version 23

Validate XHTML 1.0

## Comments

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