Extract item for each spider in scrapy project - python-3.x

Question

I have over a dozen spiders in a scrapy project with variety of items being extracted from different sources, including others elements mostly i have to copy same regex code over and over again in each spider for example
item['element'] = re.findall('my_regex', response.text)
I use this regex to get same element which is defined in scrapy items, is there a way to avoid copying? where do i put this in project so that i don't have to copy this in each spider and only add those that are different.
my project structure is default
any help is appreciated thanks in advance

Answer 1

So if I understand your question correctly, you want use the same regular expression across multiple spiders.
You can do this:
create a python module called something like regex_to_use
inside that module place your regular expression.
example:
# regex_to_use.py
regex_one = 'test'
You can access this express this one in your spiders.
# spider.py
import regex_to_use
import re as regex
find_string = regex.search(regex_to_use.regex_one, ' this is a test')
print(find_string)
# output
<re.Match object; span=(11, 15), match='test'>
You could also do something like this in your regex_to_use module
# regex_to_use.py
import re as regex
class CustomRegularExpressions(object):
def __init__(self, text):
"""
:param text: string containing the variable to search for
"""
self._text = text
def search_text(self):
find_xyx = regex.search('test', self._text)
return find_xyx
and you would call it this way in your spiders:
# spider.py
from regex_to_use import CustomRegularExpressions
find_word = CustomRegularExpressions('this is a test').search_text()
print(find_word)
# output
<re.Match object; span=(10, 14), match='test'>
If you have multiple regular expressions you could do something like this:
# regex_to_use.py
import re as regex
class CustomRegularExpressions(object):
def __init__(self, text):
"""
:param text: string containing the variable to search for
"""
self._text = text
def search_text(self, regex_to_use):
regular_expressions = {"regex_one": 'test_1', "regex_two": 'test_2'}
expression = ''.join([v for k, v in regular_expressions.items() if k == regex_to_use])
find_xyx = regex.search(expression, self._text)
return find_xyx
# spider.py
from regex_to_use import CustomRegularExpressions
find_word = CustomRegularExpressions('this is a test').search_text('regex_one')
print(find_word)
# output
<re.Match object; span=(10, 14), match='test'>
You can also use a staticmethod in the class CustomRegularExpressions
# regex_to_use.py
import re as regex
class CustomRegularExpressions:
#staticmethod
def search_text(regex_to_use, text_to_search):
regular_expressions = {"regex_one": 'test_1', "regex_two": 'test_2'}
expression = ''.join([v for k, v in regular_expressions.items() if k == regex_to_use])
find_xyx = regex.search(expression, text_to_search)
return find_xyx
# spider.py
from regex_to_use import CustomRegularExpressions
# find_word would be replaced with item['element']
# this is a test would be replaced with response.text
find_word = CustomRegularExpressions.search_text('regex_one', 'this is a test')
print(find_word)
# output
<re.Match object; span=(10, 14), match='test'>
If you use docstrings in the function search_text() you can see the regular expressions in the Python dictionary.
Showing how all this works...
This is a python project that I wrote and published. Take a look at the folder utilities. In this folder I have functions that I can use throughout my code without having to copy and paste the same code over and over.

Answer 2

There is a lot of common data that is usual to use across multiple spiders, like regex or even XPath.
It's a good idea to isolate them.
You can use something like this:
/project
/site_data
handle_responses.py
...
/spiders
your_spider.py
...
Isolate functionalities with a common purpose.
# handle_responses.py
# imports ...
from re import search
def get_specific_commom_data(text: str):
# probably is a good idea handle predictable errors here (`try except`)
return search('your_regex', text)
And just use where is needed that functionality.
# your_spider.py
# imports ...
import scrapy
from site_data.handle_responses import get_specific_commom_data
class YourSpider(scrapy.Spider):
# ... previous code
def your_method(self, response):
# ... previous code
item['element'] = get_specific_commom_data(response.text)
Try to keep it simple and do what you need to solve your problem.

Answer 3

I can copy regex in multiple spiders instead of importing object from other .py files, i understand they have the use case but here i don't want to add anything to any of the spiders but still want the element in result
There are some good answers to this but don't really solve the problem so after searching for days i have come to this solution i hope its useful for others looking for similar answer.
#middlewares.py
import yourproject.items import youritem()
#find the function and add your element
def process_spider_output(self, response, result, spider):
item = YourItem()
item['element'] = re.findall('my_regex', response.text)
now uncomment middleware from
#settings.py
SPIDER_MIDDLEWARES = {
'yourproject.middlewares.YoursprojectMiddleware': 543,
}
For each spider you will get element in result data, i am still searching for better solution and i will update the answer because it slows the spider,