View Category
XML
Parsing

Process an XML document

Given the XML Document:

<shopping>
  <item name="bread" quantity="3" price="2.50"/>
  <item name="milk" quantity="2" price="3.50"/>
</shopping>

Print out the total cost of the items, e.g. $14.50
scala
val data = <shopping>
<item name="bread" quantity="3" price="2.50"/>
<item name="milk" quantity="2" price="3.50"/>
</shopping>

val res = for (
item <- data \ "item" ;
price = (item \ "@price").text.toDouble ;
qty = (item \ "@quantity").text.toInt)
yield (price * qty)

printf("$%.2f\n", res.sum)
erlang
-include_lib("xmerl/include/xmerl.hrl").
-export([get_total/1]).

get_total(ShoppingList) ->
{XmlElt, _} = xmerl_scan:string(ShoppingList),
Items = xmerl_xpath:string("/shopping/item", XmlElt),
Total = lists:foldl(fun(Item, Tot) ->
[#xmlAttribute{value = PriceString}] = xmerl_xpath:string("/item/@price", Item),
{Price, _} = string:to_float(PriceString),
[#xmlAttribute{value = QuantityString}] = xmerl_xpath:string("/item/@quantity", Item),
{Quantity, _} = string:to_integer(QuantityString),
Tot + Price*Quantity
end,
0, Items),
io:format("$~.2f~n", [Total]).
Creation

create some XML programmatically

Given the following CSV:

bread,3,2.50
milk,2,3.50

Produce the equivalent information in XML, e.g.:

<shopping>
  <item name="bread" quantity="3" price="2.50" />
  <item name="milk" quantity="2" price="3.50" />
</shopping>
scala
<shopping>
{List("bread,3,2.50", "milk,2,3.50") map { row =>
row split ","
} map { item =>
<item name={item(0)} quantity={item(1)} price={item(2)}/>
}}
</shopping>
erlang
to_xml(ShoppingList) ->
Items = lists:map(fun(L) ->
[Name, Quantity, Price] = string:tokens(L, ","),
{item, [{name, Name}, {quantity, Quantity}, {price, Price}], []}
end, string:tokens(ShoppingList, "\n")),
xmerl:export_simple([{shopping, [], Items}], xmerl_xml).