這邊我是打API爬的，所以先寫了序列化：

class IgCommentsSerializer(serializers.Serializer):
    post = serializers.CharField(max_length=1000)
    poster = serializers.CharField(max_length=200)

一開始先寫selenium的webserver基本設定，要抓取全部留言的話需先登入完ig，再跳轉到要的post頁面：

class IgComments(APIView):
    def __init__(self):
        self.path = 'chromedriver的路徑'
        self.sbaccount = '帳號'
        self.sbpd = '密碼'

    def post(self, request):
        options = Options()
        options.add_argument("--headless") # 執行時瀏覽器只在背景執行
        driver = webdriver.Chrome(self.path, options=options)
        driver.implicitly_wait(3)
        driver.get('https://www.instagram.com/') 
        time.sleep(2)
        account = driver.find_elements_by_name('username')[0]
        pd = driver.find_elements_by_name('password')[0]
        # 登入
        account.send_keys(self.sbaccount)
        pd.send_keys(self.sbpd)
        driver.find_element_by_xpath('//*[@id="loginForm"]/div/div[3]/button').click()  
        time.sleep(3)
        driver.get('https://www.instagram.com/p/CYXqAMuBX0e/') # 直接跳轉到post
        more_xpath = '//*[@id="react-root"]/section/main/div/div[1]/article/div/div[2]/div/div[2]/div[1]/ul/li/div/button/div'
        time.sleep(2)

ig一次只會載入12則留言(我沒記錯的話XD)，這邊需要借助selenium的力量，自動化點選更多留言按鈕。而為了要抓取所有留言，這邊透過while迴圈直到沒有更多留言按鈕可點選，之後就可以一次性地抓取所有留言文字了：

...接下上部分程式碼...
        while True:
            try:
                time.sleep(2)
                driver.find_element_by_xpath(more_xpath).click()
                print('下一頁')
            except:
                print('最後一頁')
                break
        crawl_comments = []
        comments = driver.find_element_by_class_name("XQXOT").find_elements_by_class_name("Mr508")
        n = 1
        for c in comments:
            poster = c.find_element_by_css_selector('h3._6lAjh span').text
            post_xpath = f'//*[@id="react-root"]/section/main/div/div[1]/article/div/div[2]/div/div[2]/div[1]/ul/ul[{n}]/div/li/div/div/div[2]/span'.format(n=n)
            time.sleep(2)
            post = c.find_element_by_xpath(post_xpath).text
            crawl_comments.append({'poster':poster, 'post':post})
            n+=1
        ser = IgCommentsSerializer(crawl_comments, many=True)
        return Response(ser.data)