[FIXED] Yield or return for Scrapy?

Issue

I read several different examples/articles but I am still not sure about yield and return. I have two examples here from my code where I asked me that question. Which one to use?

spider.py

class LatindancecalendarSpider(CrawlSpider):
    name = "latindancecalendar"
    allowed_domains = ["latindancecalendar.com"]
    start_urls = ["https://latindancecalendar.com/festivals/"]

    rules = (
        Rule(
            LinkExtractor(
                restrict_xpaths=("//div[@class='eventline event_details']/a")
            ),
            callback="parse_event",
        ),
    )

    def parse_event(self, response):
        # event = ItemLoader(item=LatinDanceCalendarItem(), response=response)
        event = LatinDanceCalendarItemLoader(
            item=LatinDanceCalendarItem(), response=response
        )
        # event.default_output_processor = TakeFirst()
        event.add_xpath("name", '//h1[@class="page-title"]/text()')
        event.add_xpath("date", '//div[@class="vevent"]/div/span/b/text()')
        return event.load_item()  # yield or return?

items.py

def lowercase_processor(self, values):
    for v in values:
        yield v.lower()  # yield or return?

class LatinDanceCalendarItemLoader(ItemLoader):
    default_output_processor = TakeFirst()

    city_in = lowercase_processor

Solution

Yield will return a generator. The return will only return the first v in values and the rest of the loop is skipped. Basically if you use yield, you will get back a generator with all the values in lowercase. If you use a return it will just return the first value in lowercase.

Answered By - user12541086