PostgreSQL psycopg2 返回一个字符串元组而不是元组元组? [英] PostgreSQL psycopg2 returns a tuple of strings instead of tuple of tuples?

问题描述

我有一个奇怪的问题，在搜索 Google/SO 后我不太确定如何解决它.

I have a weird problem, and I'm not too sure how to fix it after searching Google/SO found nothing similar.

当我试图从游标中获取查询结果时，它给了我一个元组元组，除了元组是字符串?下面是代码.

When I tried to grab query results from the cursor, it gives me a tuple of tuples, except the tuples are strings? Below is the code.

def queryFeeds(db):
   sql = """SELECT ngo.n_id, feeds.url FROM ngo 
    JOIN feeds ON ngo.n_id = feeds.n_id;"""

   db.c.execute(sql)

   feeds = db.c.fetchall()

   return feeds

这里的打印输出是函数返回的 feeds 变量:

The print output is here for the feeds variable returned by the function:

feeds[0]
('(277,http://resultsuk.wordpress.com/feed)',)

feeds[0][0]
'(277,http://resultsuk.wordpress.com/feed)'

type(feeds[0][0])
<type 'str'>

feeds[0][0][0:10]
'(277,http:'

db 只是一个有数据库连接的类，其中 db.c 是游标.提前致谢.删除的数据是 http://链接，因为我的声誉低，所以不会让我发布.

The db is just a class that has the database connection, where db.c is the cursor. Thanks in advance. The deleted data are http: // links that SO won't let me post because of my low reputation.

干杯，

卢卡斯

推荐答案

从 SELECT 子句中的字段中删除括号.

Remove the parentheses from the fields in the SELECT clause.

我遇到了同样的问题(尽管使用 RETURNING 子句而不是 SELECT)，@user2524674 的评论应该是一个答案.在编辑问题之前，SELECT 子句中的字段用括号括起来，即

I had this same issue (though with a RETURNING clause instead of a SELECT), and the comment by @user2524674 deserves to be an answer. Before the question was edited, the fields in the SELECT clause were surrounded by parentheses, i.e.

SELECT (ngo.n_id, feeds.url)

并且返回的结果是一个字符串而不是一个实际的元组.将此更改为

and the result returned is a string rather than an actual tuple. Changing this to

SELECT ngo.n_id, feeds.url

导致 psycopg2 返回一个实际的值元组.

causes psycopg2 to return an actual tuple of values.

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