psycopg2将Python：“字典列表”映射到Postgres：“ INSERT语句的复合类型数组”

Postgres版本：9.1.x.

说我有以下架构：

DROP TABLE IF EXISTS posts CASCADE;
DROP TYPE IF EXISTS quotes CASCADE;

CREATE TYPE quotes AS
(
  text  CHaraCTER varying,
  is_direct CHaraCTER varying
);

CREATE TABLE posts
(
    body  CHaraCTER varying,
    q     quotes[]
);

我希望执行以下插入操作(以sql所示),但是要从Python Psycopg2执行.

insert into posts(body,q) VALUES('ninjas rock',ARRAY[ ROW('I AGREE',True)::quotes, ROW('I disAGREE',FALSE)::quotes ]);

实现此目的的语法是什么(没有循环等).我确信自documentation says“在2.4.3版中已更改：添加了对复合类型数组的支持”以来,这是可能的.该文档仅显示SELECT语句的示例.

注意：我的客户端代码中有一系列字典,这些字典在概念上映射到上面的psuedo模式.

编辑：

嗯,我一定从文档中错过了这一点：“相反,从Python元组到复合类型的自适应是自动的,不需要适配器注册.”现在找出阵列部分.

编辑2：

当传递的数据类型为list(tuple)或list(dict)时,psycopg2的％s占位符应该起作用.要测试一下：D

编辑3：
好的,到此为止,字典在这种情况下不起作用,列表可以,而元组可以.但是,我需要将元组字符串表示形式转换为复合记录类型.

这个：

quote_1 = ("monkeys rock", "False")
quote_2 = ("donkeys rock",  "True")
q_list = [ quote_1, quote_2]
print cur.mogrify("insert into posts VALUES(%s,%s)", ("animals are good", q_list))

创建以下字符串：

insert into posts VALUES('animals are good',ARRAY[('monkeys rock', 'false'), ('donkeys rock', 'true')])

产生以下错误：

psycopg2.ProgrammingError: column "q" is of type quotes[] but expression is of type record[]

解决方法:

稍加努力,如何：

quote_1 = ("monkeys rock", "False")
quote_2 = ("donkeys rock",  "True")
q_list = [ quote_1, quote_2]
print cur.mogrify("insert into posts VALUES(%s,%s::quotes[])", 
                  ("animals are good", q_list))
#
#                 added explicit cast to quotes[]->^^^^^^^^

说明：

如果您运行：

insert into posts 
VALUES('animals are good', ARRAY[
    ('monkeys rock', 'false'),
    ('donkeys rock', 'true')
]);

直接在psql中,您将获得：

regress=# insert into posts 
regress-# VALUES('animals are good',ARRAY[
regress-#             ('monkeys rock', 'false'),
regress-#             ('donkeys rock', 'true')
regress-#  ]);
ERROR:  column "q" is of type quotes[] but expression is of type record[]
LINE 1: insert into posts VALUES('animals are good',ARRAY[('monkeys ...
                                                    ^
HINT:  You will need to rewrite or cast the expression.

果然,告诉Pg您的匿名数组的类型为quotes []可以解决这个问题：

regress=# insert into posts 
regress-# VALUES('animals are good',ARRAY[
regress-#           ('monkeys rock', 'false'),
regress-#           ('donkeys rock', 'true')
regress-# ]::quotes[]);
INSERT 0 1

regress=# select * from posts;
       body       |                           q                            
------------------+--------------------------------------------------------
 animals are good | {"(\"monkeys rock\",false)","(\"donkeys rock\",true)"}
(1 row)

psycopg2将Python：“字典列表”映射到Postgres：“ INSERT语句的复合类型数组”

相关文章