Make scrapy follow links in order

Question

I wrote a script and used Scrapy to find links in the first phase and follow the links and extract something from the page in the second phase. Scrapy DOES it BUT it follows the links in an unordered manner, i.e. I expect an output as below:

link1 | data_extracted_from_link1_destination_page
link2 | data_extracted_from_link2_destination_page
link3 | data_extracted_from_link3_destination_page
.
.
.

but I get

link1 | data_extracted_from_link2_destination_page
link2 | data_extracted_from_link3_destination_page
link3 | data_extracted_from_link1_destination_page
.
.
.

here is my code:

import scrapy


class firstSpider(scrapy.Spider):
    name = "ipatranscription"
    start_urls = ['http://www.phonemicchart.com/transcribe/biglist.html']

    def parse(self, response):
        body = response.xpath('./body/div[3]/div[1]/div/a')
        LinkTextSelector = './text()'
        LinkDestSelector = './@href'

        for link in body:
            LinkText = link.xpath(LinkTextSelector).extract_first()
            LinkDest = response.urljoin(link.xpath(LinkDestSelector).extract_first())

            yield {"LinkText": LinkText}
            yield scrapy.Request(url=LinkDest, callback=self.parse_contents)

    def parse_contents(self, response):

        lContent = response.xpath("/html/body/div[3]/div[1]/div/center/span/text()").extract()
        sContent = ""
        for i in lContent:
            sContent += i
        sContent = sContent.replace("\n", "").replace("\t", "")
        yield {"LinkContent": sContent}

What is wrong in my code?

Answer 1

yield is not synchronous, you should use meta to achieve this. Doc: https://doc.scrapy.org/en/latest/topics/request-response.html
Code:

import scrapy
class firstSpider(scrapy.Spider):
    name = "ipatranscription"
    start_urls = ['http://www.phonemicchart.com/transcribe/biglist.html']
    def parse(self, response):
        body = response.xpath('./body/div[3]/div[1]/div/a')
        LinkTextSelector = './text()'
        LinkDestSelector = './@href'
        for link in body:
            LinkText = link.xpath(LinkTextSelector).extract_first()
            LinkDest = 
              response.urljoin(link.xpath(LinkDestSelector).extract_first())
            yield scrapy.Request(url=LinkDest, callback=self.parse_contents, meta={"LinkText": LinkText})

    def parse_contents(self, response):
        lContent = 
response.xpath("/html/body/div[3]/div[1]/div/center/span/text()").extract()
        sContent = ""
        for i in lContent:
            sContent += i
        sContent = sContent.replace("\n", "").replace("\t", "")
        linkText = response.meta['LinkText']
        yield {"LinkContent": sContent,"LinkText": linkText}