psycopg2 在“$body$”处或附近抛出未终止的美元引号字符串错误

Question

我正在尝试构建一个 alembic 迁移修订版以在 PostgreSQL 服务器版本 10.2 中创建一个用户定义的函数，但是脚本不断抛出错误：

sqlalchemy.exc.ProgrammingError: (psycopg2.ProgrammingError) unterminated dollar-quoted string at or near "$body$
                select string_agg(convert_to(coalesce(r[2], length(length(r[1])::text) || length(r[1])::text || r[1]), 'SQL_ASCII'), '"
    LINE 6:         as $body$
                       ^
     [SQL: "\n        create or replace function naturalsort(text)\n          returns bytea\n          language sql\n          immutable strict\n        as $body$ \n            select string_agg(convert_to(coalesce(r[2], length(length(r[1])::text) || length(r[1])::text || r[1]), 'SQL_ASCII'), '\x00') from regexp_matches(, '0*([0-9]+)|([^0-9]+)', 'g') r; \n        $body$;\n    "] (Background on this error at: http://sqlalche.me/e/f405)

我的剧本运行:

def upgrade():
    conn = op.get_bind()

    conn.execute('DROP FUNCTION IF EXISTS "naturalsort"')

    conn.execute("""
        create or replace function naturalsort(text)
          returns bytea
          language sql
          immutable strict
        as $body$ 
            select string_agg(convert_to(coalesce(r[2], length(length(r[1])::text) || length(r[1])::text || r[1]), 'SQL_ASCII'), '\x00') from regexp_matches(, '0*([0-9]+)|([^0-9]+)', 'g') r; 
        $body$;
    """)

该代码应允许对列进行自然排序，并且是 rhodium toad 的 copy/paste。

由于美元引号字符串是重写字符串常量的一种方式，替代方法是（请注意 postgresql 文档中的双单引号："To include a single-quote character within a string constant, write two adjacent single quotes, e.g., 'Dianne''s horse'. Note that this is not the same as a double-quote character ("）。” ):

conn.execute("""
    create or replace function naturalsort(text)
      returns bytea
      language sql
      immutable strict
    as 'select string_agg(convert_to(coalesce(r[2], length(length(r[1])::text) || length(r[1])::text || r[1]), ''SQL_ASCII''), ''\x00'') from regexp_matches(, ''0*([0-9]+)|([^0-9]+)'', ''g'') r;';
""")

但是这会引发类似的错误：

sqlalchemy.exc.ProgrammingError: (psycopg2.ProgrammingError) unterminated quoted string at or near "'select string_agg(convert_to(coalesce(r[2], length(length(r[1])::text) || length(r[1])::text || r[1]), ''SQL_ASCII''), ''"
LINE 6:         as 'select string_agg(convert_to(coalesce(r[2], leng...
                   ^
 [SQL: "\n        create or replace function naturalsort(text)\n          returns bytea\n          language sql\n          immutable strict\n        as 'select string_agg(convert_to(coalesce(r[2], length(length(r[1])::text) || length(r[1])::text || r[1]), ''SQL_ASCII''), ''\x00'') from regexp_matches(, ''0*([0-9]+)|([^0-9]+)'', ''g'') r;';\n    "] (Background on this error at: http://sqlalche.me/e/f405)

奇怪的是，这些查询在 pgAdmin 中执行得很好，而且 alembic 似乎生成了有效的 SQL（alembic 升级：--sql）：

DROP FUNCTION IF EXISTS "naturalsort";

create or replace function naturalsort(text)
          returns bytea
          language sql
          immutable strict
        as $body$
            select string_agg(convert_to(coalesce(r[2], length(length(r[1])::text) || length(r[1])::text || r[1]), 'SQL_ASCII'), '') from regexp_matches(, '0*([0-9]+)|([^0-9]+)', 'g') r;
        $body$;;

UPDATE alembic_version SET version_num='ad99fdcb28bc' WHERE alembic_version.version_num = 'ff00ac684617';

COMMIT;

关于为什么 psycopg2 不断抛出 unterminated dollar-quoted string at or near "$body$ 错误的任何线索？

Answer 1

$body 是一个不能包含 $ 的别名，将 $body$ 替换为 my_body 这样的名称，它应该可以工作

Answer 2

def upgrade():
    op.execute('DROP FUNCTION IF EXISTS "naturalsort"')

    op.execute("""
      create or replace function naturalsort(text)
      returns bytea
      language sql
      immutable strict
    as $my_body$
        select string_agg(convert_to(coalesce(r[2], length(length(r[1])::text) || length(r[1])::text || r[1]), 'SQL_ASCII'), '') from regexp_matches(, '0*([0-9]+)|([^0-9]+)', 'g') r;
    $my_body$;;
    """)


def downgrade():
    op.execute('DROP FUNCTION IF EXISTS "naturalsort"')

执行升级时，它成功了，没有语法错误。实际上在 postgres 中执行该函数也会使用此查询返回所需的自然排序结果：

SELECT * FROM public.requirement ORDER BY naturalsort(eid) asc

使用 PvdL 关于 my_body 的评论部分起作用，如果我在空字符串现在所在的位置添加 '\x00'（在 SQL_ASCII 之后），它将引发语法错误

psycopg2 在“$body$”处或附近抛出未终止的美元引号字符串错误

psycopg2 throws unterminated dollar-quoted string error at or near "$body$"

postgresql

sqlalchemy

psycopg2

python-3.x

alembic