.. _templating:
==============================
Cleaner Scripts with Templates
==============================
When you want script to return richer output or say HTML page, separation of
script and markup is a good idea. Spidy has special ``merge`` command to accomplish
that. It simply merges script context with specified template file and puts
results into a variable. Script context is basically all defined variables at
the current execution step.
.. note:: As oppose to Python, Spidy's variables have scope, meaning, loop
variables or variables defined in ``if``, ``while``, ``traverse`` or ``for``
statement's body will no longer be available after the statement's body is
executed.
Currencies Example
==================
The following example also returns HTML page, but this time we will format results
as table. To demonstrate how it can be accomplished using templates, lets scrap
currencies data from Reuters and Yahoo finance sites::
1
2 // cookies - off
3 // javascript - off
4
5 agent = 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:27.0) Gecko/20100101 Firefox/27.0'
6 reuters = ['http://www.reuters.com/finance/global-market-data', 'Reuters', '//table[@id="currPairs"]/tbody[1]', '//a[1]', '/td[2]']
7 yahoo = ['http://finance.yahoo.com/currency-investing', 'Yahoo Finance', '//table[@id="flat-rates-table"]/tbody[1]', '//a[@class="currency-link"][1]', '/td[2]']
8 sources = [reuters, yahoo]
9 markup = ''
10
11 for src in sources:
12 get src[0] as html:
13 User-Agent: agent
14
15 if & != None:
16 header = src[1]
17 pairs = ''
18 prices = ''
19 traverse tr in &src[2]:
20 pair = &(tr + src[3])
21 price = &(tr + src[4])
22 merge 'currencies_pair.spt' as pair
23 merge 'currencies_price.spt' as price
24 pairs = pairs + pair
25 prices = prices + price
26 merge 'currencies_rows.spt' as row
27 markup = markup + row
28
29 merge 'currencies_page.spt' as markup
30 return markup
**Lines 6, 7** - for convenience, we keep site's URL, name and container, pair,
price XPath selectors in one list, so the script flow can be simplified.
**Lines 22, 23** - using ``merge`` command script produces table cells for
currency pair name and price value.
*currencies_pair.spt*::
| ${pair} |
*currencies_price.spt*::
${price} |
**Line 26** - resulting row header, pair name and price value are merged with
table row template.
*currencies_rows.spt*::
| ${header} |
${pairs}
${prices}
**Line 29** - finally, rows markup is merged with main document template.
*currencies_page.spt*::