环路执行功能

Question

下破坏我有代码如下：

def scrapeFacebookPageFeedStatus(access_token): 

    query = "SELECT page_id FROM falken" 

    result_list = c.execute(query) 

    for single_row in result_list: 

     str_single_row = str(single_row) 

     str_norm_single_row = str_normalize(str_single_row) 

     print(str_norm_single_row) 

当我执行上面的代码，它从result_list显示每SINGLE_ROW值。

但是当我通过SINGLE_ROW到功能象下面这样：

def scrapeFacebookPageFeedStatus(access_token): 

    query = "SELECT page_id FROM falken" 

    result_list = c.execute(query) 

    for single_row in result_list: 

     str_single_row = str(single_row) 

     str_norm_single_row = str_normalize(str_single_row) 

     print(str_norm_single_row) 

     statuses = getFacebookPageFeedData(str_norm_single_row, access_token, 100) 

     for status in statuses['data']: 

      query = "INSERT INTO falken_posts VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)" 

      c.execute(query,(processFacebookPageFeedStatus(status, access_token))) 

      conn.commit() 

它仅通过的SINGLE_ROW给函数的第一值和所述循环停止。

getFacebookPageFeedData功能

def getFacebookPageFeedData(page_id, access_token, num_statuses): 

base = "https://graph.facebook.com/v2.6" 
node = "/%s/posts" % page_id 
fields = "/?fields=message,link,created_time,type,name,id," + \ 
     "comments.limit(0).summary(true),shares,reactions" + \ 
     ".limit(0).summary(true)" 
parameters = "&limit=%s&access_token=%s" % (num_statuses, access_token) 
url = base + node + fields + parameters 

# retrieve data 
data = json.loads(request_until_succeed(url)) 

return data 

它从页的帖子Facebook的图形API检索数据。

processFacebookPageFeedStatus功能

def processFacebookPageFeedStatus(status, access_token): 

    status_id = status['id'] 
    status_message = '' if 'message' not in status.keys() else \ 
     unicode_normalize(status['message']) 
    link_name = '' if 'name' not in status.keys() else \ 
     unicode_normalize(status['name']) 
    status_type = status['type'] 
    status_link = '' if 'link' not in status.keys() else \ 
     unicode_normalize(status['link']) 

    status_published = datetime.datetime.strptime(
     status['created_time'],'%Y-%m-%dT%H:%M:%S+0000') 
    status_published = status_published + \ 
     datetime.timedelta(hours=-5) # EST 
    status_published = status_published.strftime(
     '%Y-%m-%d %H:%M:%S') 

    num_reactions = 0 if 'reactions' not in status else \ 
     status['reactions']['summary']['total_count'] 
    num_comments = 0 if 'comments' not in status else \ 
     status['comments']['summary']['total_count'] 
    num_shares = 0 if 'shares' not in status else status['shares']['count'] 

    reactions = getReactionsForStatus(status_id, access_token) if \ 
     status_published > '2016-02-24 00:00:00' else {} 

    num_likes = 0 if 'like' not in reactions else \ 
     reactions['like']['summary']['total_count'] 

    num_likes = num_reactions if status_published < '2016-02-24 00:00:00' \ 
     else num_likes 

IT卖场需要从状态字典，并将其存储到变量数据插入到数据库中。

Answer 1

sqlite的cursor.execute()返回光标本身。所以这行之后：

result_list = c.execute(query) 

result_list实际上是c的别名。

现在你开始遍历c：

for single_row in result_list: 
    # code here 

，然后再次调用c.execute()：

query = "INSERT INTO falken_posts VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)" 
    c.execute(query,(processFacebookPageFeedStatus(status, access_token))) 

其丢弃c的前面的结果与这个新的查询结果集。由于此查询不会选择任何内容，因此c将变为空的迭代器，并且您的循环停在那里。

固化是简单明了：使用另一个光标插入查询，这样你就不会覆盖c的结果集：

# create a second cursor for insert statements 
writer = conn.cursor() 
# no need to recreate this same string anew for each iteration, 
# we can as well define it here once for all 
insert_query = "INSERT INTO falken_posts VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)" 

# no need for result_list - just iterate over `c` 
c.execute(query) 
for single_row in c: 
    # code here 
    writer.execute(insert_query,(processFacebookPageFeedStatus(status, access_token))) 

作为一个侧面说明，如果性能是一个问题，你可能还希望在整个循环之后提交一次，而不是在每个插入语句之后提交。