Scrapy python csv输出在每行之间有空行

Question

I am getting unwanted blank lines between each row of scrapy output in the resulting csv output file.

I have moved from python2 to python 3, and I use Windows 10. I am therefore in the process of adapting my scrapy projects for python3.

My current (and for now, sole) problem is that when I write the scrapy output to a CSV file I get a blank line between each row. This has been highlighted on several posts here (it is to do with Windows) but I am unable to get a solution to work.

As it happens, I have also added some code to the piplines.py file to ensure the csv output is in a given column order and not some random order. Hence, I can use the normal scrapy crawl charleschurch to run this code rather than the scrapy crawl charleschurch -o charleschurch2017xxxx.csv

Does anyone know how to skip / omit this blank line in the CSV output?

My pipelines.py code is below (I perhaps don't need the import csv line but I suspect I may do for the final answer):

# -*- coding: utf-8 -*-

# Define your item pipelines here
#
# Don't forget to add your pipeline to the ITEM_PIPELINES setting
# See: http://doc.scrapy.org/en/latest/topics/item-pipeline.html

import csv
from scrapy import signals
from scrapy.exporters import CsvItemExporter

class CSVPipeline(object):

  def __init__(self):
    self.files = {}

  @classmethod
  def from_crawler(cls, crawler):
    pipeline = cls()
    crawler.signals.connect(pipeline.spider_opened, signals.spider_opened)
    crawler.signals.connect(pipeline.spider_closed, signals.spider_closed)
    return pipeline

  def spider_opened(self, spider):
    file = open('%s_items.csv' % spider.name, 'w+b')
    self.files[spider] = file
    self.exporter = CsvItemExporter(file)
    self.exporter.fields_to_export = ["plotid","plotprice","plotname","name","address"]
    self.exporter.start_exporting()

  def spider_closed(self, spider):
    self.exporter.finish_exporting()
    file = self.files.pop(spider)
    file.close()

  def process_item(self, item, spider):
    self.exporter.export_item(item)
    return item

I added this line to the settings.py file (not sure the relevance of the 300):

ITEM_PIPELINES = {'CharlesChurch.pipelines.CSVPipeline': 300 }

my scrapy code is below:

import scrapy
from urllib.parse import urljoin

from CharlesChurch.items import CharleschurchItem

class charleschurchSpider(scrapy.Spider):
    name = "charleschurch"
    allowed_domains = ["charleschurch.com"]    
    start_urls = ["https://www.charleschurch.com/county-durham_willington/the-ridings-1111"]


    def parse(self, response):

        for sel in response.xpath('//*[@id="aspnetForm"]/div[4]'):
           item = CharleschurchItem()
           item['name'] = sel.xpath('//*[@id="XplodePage_ctl12_dsDetailsSnippet_pDetailsContainer"]/span[1]/b/text()').extract()
           item['address'] = sel.xpath('//*[@id="XplodePage_ctl12_dsDetailsSnippet_pDetailsContainer"]/div/*[@itemprop="postalCode"]/text()').extract()
           plotnames = sel.xpath('//div[@class="housetype js-filter-housetype"]/div[@class="housetype__col-2"]/div[@class="housetype__plots"]/div[not(contains(@data-status,"Sold"))]/div[@class="plot__name"]/a/text()').extract()
           plotnames = [plotname.strip() for plotname in plotnames]
           plotids = sel.xpath('//div[@class="housetype js-filter-housetype"]/div[@class="housetype__col-2"]/div[@class="housetype__plots"]/div[not(contains(@data-status,"Sold"))]/div[@class="plot__name"]/a/@href').extract()
           plotids = [plotid.strip() for plotid in plotids]
           plotprices = sel.xpath('//div[@class="housetype js-filter-housetype"]/div[@class="housetype__col-2"]/div[@class="housetype__plots"]/div[not(contains(@data-status,"Sold"))]/div[@class="plot__price"]/text()').extract()
           plotprices = [plotprice.strip() for plotprice in plotprices]
           result = zip(plotnames, plotids, plotprices)
           for plotname, plotid, plotprice in result:
               item['plotname'] = plotname
               item['plotid'] = plotid
               item['plotprice'] = plotprice
               yield item

Answer 1

i suspect not ideal but I have found a work around to this problem. In the pipelines.py file I have added more code that essentially reads the csv file with the blank lines to a list, and so removes the blank lines and then writes that cleaned list to a new file.

the code I added is:

with open('%s_items.csv' % spider.name, 'r') as f:
  reader = csv.reader(f)
  original_list = list(reader)
  cleaned_list = list(filter(None,original_list))

with open('%s_items_cleaned.csv' % spider.name, 'w', newline='') as output_file:
    wr = csv.writer(output_file, dialect='excel')
    for data in cleaned_list:
      wr.writerow(data)

and so the entire pipelines.py file is:

# -*- coding: utf-8 -*-

# Define your item pipelines here
#
# Don't forget to add your pipeline to the ITEM_PIPELINES setting
# See: http://doc.scrapy.org/en/latest/topics/item-pipeline.html

import csv
from scrapy import signals
from scrapy.exporters import CsvItemExporter

class CSVPipeline(object):

  def __init__(self):
    self.files = {}

  @classmethod
  def from_crawler(cls, crawler):
    pipeline = cls()
    crawler.signals.connect(pipeline.spider_opened, signals.spider_opened)
    crawler.signals.connect(pipeline.spider_closed, signals.spider_closed)
    return pipeline

  def spider_opened(self, spider):
    file = open('%s_items.csv' % spider.name, 'w+b')
    self.files[spider] = file
    self.exporter = CsvItemExporter(file)
    self.exporter.fields_to_export = ["plotid","plotprice","plotname","name","address"]
    self.exporter.start_exporting()

  def spider_closed(self, spider):
    self.exporter.finish_exporting()
    file = self.files.pop(spider)
    file.close()

    #given I am using Windows i need to elimate the blank lines in the csv file
    print("Starting csv blank line cleaning")
    with open('%s_items.csv' % spider.name, 'r') as f:
      reader = csv.reader(f)
      original_list = list(reader)
      cleaned_list = list(filter(None,original_list))

    with open('%s_items_cleaned.csv' % spider.name, 'w', newline='') as output_file:
        wr = csv.writer(output_file, dialect='excel')
        for data in cleaned_list:
          wr.writerow(data)

  def process_item(self, item, spider):
    self.exporter.export_item(item)
    return item


class CharleschurchPipeline(object):
    def process_item(self, item, spider):
        return item

not ideal but solves the problem for now.

Answer 2

The b in w+b is most probably part of the problem as this will make the file being considered a binary file and so linebreaks are written as is.

So first step is to remove the b . And then by adding U you can also activate the Universal Newline support ( see: https://docs.python.org/3/glossary.html#term-universal-newlines )

So the line in question should look like:

file = open('%s_items.csv' % spider.name, 'Uw+')