Settings View Source xmerl_xml_indent

Erlang OTP's built-in xmerl module lacks the functionality to print XML with indentation. This module is an alternative to xmerl_xml to print XML with indentation.

This module is taken from https://github.com/erlang/otp/blob/master/lib/xmerl/src/xmerl_xml.erl, converted to Elixir and modified for indentation.

As the module name suggests, this library must be used in conjunction with Erlang's built-in xmerl library.

Installation

Add xmerl_xml_indent to your list of dependencies in mix.exs:

def deps do
  [
    {:xmerl_xml_indent, "~> 0.2.0"}
  ]
end

Usage

xml_str = "<?xml version = \"1.0\"?><Level1><Level2><Level3A>This is level 3</Level3A><Level3B>This is level 3B</Level3B><Level3C><Level4>This is level 4</Level4><Level4B><Level5>This is level 5</Level5></Level4B></Level3C></Level2></Level1>"

xml_chars = String.to_charlist(xml_str)
{xml_parsed, _} = :xmerl_scan.string(xml_chars)
xml_exported = :xmerl.export([xml_parsed], XmerlXmlIndent)
to_string(xml_exported)

The above code produces XML output:

<?xml version="1.0"?>
<Level1>
  <Level2>
    <Level3A>This is level 3A</Level3A>
    <Level3B>This is level 3B</Level3B>
    <Level3C>
      <Level4>This is level 4</Level4>
      <Level4B>
        <Level5>This is level 5</Level5>
      </Level4B>
    </Level3C>
  </Level2>
</Level1>

Customizing End of Line (EOL) and Indent characters

XmerlXmlIndent uses LF (\n) as the EOL character and two spaces as the indent.

If you want to customize this behavior, you can create a custom module. For example:

defmodule XmerlXmlIndentCustom do
  use XmerlXmlIndentBase

  def new_line() do
    "\r\n"
  end

  def indent() do
    "\t"
  end
end