1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
|
======= =========================================
SEP 06
Title Extractors
Author Ismael Carnales and a bunch of rabid mice
Created 2009-07-28
Status Obsolete (discarded)
======= =========================================
==========================================
SEP-006: Rename of Selectors to Extractors
==========================================
This SEP proposes a more meaningful naming of XPathSelectors or "Selectors" and
their ``x`` method.
Motivation
==========
When you use Selectors in Scrapy, your final goal is to "extract" the data that
you've selected, as the [https://docs.scrapy.org/en/latest/topics/selectors.html
XPath Selectors documentation] says (bolding by me):
When you’re scraping web pages, the most common task you need to perform is
to **extract** data from the HTML source.
..
Scrapy comes with its own mechanism for **extracting** data. They’re called
``XPath`` selectors (or just “selectors”, for short) because they “select”
certain parts of the HTML document specified by ``XPath`` expressions.
..
To actually **extract** the textual data you must call the selector
``extract()`` method, as follows
..
Selectors also have a ``re()`` method for **extracting** data using regular
expressions.
..
For example, suppose you want to **extract** all <p> elements inside <div>
elements. First you get would get all <div> elements
Rationale
=========
As and there is no ``Extractor`` object in Scrapy and what you want to finally
perform with ``Selectors`` is extracting data, we propose the renaming of
``Selectors`` to ``Extractors``. (In Scrapy for extracting you use selectors is
really weird :) )
Additional changes
==================
As the name of the method for performing selection (the ``x`` method) is not
descriptive nor mnemotechnic enough and clearly clashes with ``extract`` method
(x sounds like a short for extract in english), we propose to rename it to
``select``, ``sel`` (is shortness if required), or ``xpath`` after `lxml's
<http://lxml.de/xpathxslt.html>`_ ``xpath`` method.
Bonus (ItemBuilder)
===================
After this renaming we propose also renaming ``ItemBuilder`` to ``ItemExtractor``,
because the ``ItemBuilder``/``Extractor`` will act as a bridge between a set of
``Extractors`` and an ``Item`` and because it will literally "extract" an item from a
webpage or set of pages.
References
==========
1. XPath Selectors (https://docs.scrapy.org/topics/selectors.html)
2. XPath and XSLT with lxml (http://lxml.de/xpathxslt.html)
|
