Thursday, September 26, 2013

Convert color console output into HTML with Java

Some command line tools can print colored text, which looks nice in console itself (if it is supported), but not so nice when you need to show it in HTML:

[47;32mhello world

There is small console tool "aha" that can pipe such input and transform it directly in command line, but sometimes you have to do it from code. For such cases there is Java library Jansi which prints ANSI escape sequences into Windows consoles. Their less advertised feature is library for direct conversion between ANSI and HTML, which it does just fine:

    @Grab(group='org.fusesource.jansi', module='jansi', version='1.11')

import org.fusesource.jansi.*

private String colorize(String text) throws IOException {
  new ByteArrayOutputStream().with {
    new HtmlAnsiOutputStream(it).with {
    return new String(it.toByteArray(), "UTF-8");

println colorize(" [47;32mhello world")

Thursday, September 5, 2013

Adding error messages to domain object in Grails

Sometimes it is more convenient to do some validation outside of the domain object, on the other side it is still nice to use standard error reporting facilities. For these cases, you can inject errors into domain objects like:

    if (someError) {
      domainobject.errors.rejectValue('param', "hasErrors")
    if (!domainobject.hasErrors() && true)) {