DictCursor在psycopg2下似乎不起作用 [英] DictCursor doesn't seem to work under psycopg2

问题描述

我以前没有使用过psycopg2，但是我试图将光标工厂更改为DictCursor，以便fetchall或fetchone将返回字典而不是列表.

I haven't worked with psycopg2 before but I'm trying to change the cursor factory to DictCursor so that fetchall or fetchone will return a dictionary instead of a list.

我创建了一个测试脚本来简化操作，并且仅测试此功能.这是我觉得应该可以使用的一些代码

I created a test script to make things simple and only test this functionality. Here's my little bit of code that I feel should work

import psycopg2
import psycopg2.extras

conn = psycopg2.connect("dbname=%s user=%s password=%s" % (DATABASE, USERNAME, PASSWORD))

cur = conn.cursor(cursor_factory = psycopg2.extras.DictCursor)
cur.execute("SELECT * from review")

res = cur.fetchall()

print type(res)
print res

res变量始终是列表，而不是我期望的字典.

The res variable is always a list and not a dictionary as I would expect.

我目前实现的解决方法是使用此功能来构建字典，并通过它运行fetchall返回的每一行.

A current workaround that I've implemented is to use this function that builds a dictionary and run each row returned by fetchall through it.

def build_dict(cursor, row):
    x = {}
    for key,col in enumerate(cursor.description):
        x[col[0]] = row[key]
    return d

Python的版本为2.6.7，而psycopg2的版本为2.4.2.

Python is version 2.6.7 and psycopg2 is version 2.4.2.

推荐答案

res = cur.fetchall()

使res成为psycopg2.extras.DictRow s的列表.

或者，您可以利用cur是可迭代的这一事实来代替调用cur.fetchall:

Alternatively, instead of calling cur.fetchall you can take advantage of the fact that cur is an iterable:

cur.execute("SELECT * from review")
for row in cur:
    print(row['column_name'])

，因此您将能够使用类似dict的语法来访问数据.

and thus you'll be able to access the data with dict-like syntax.

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