Postgres array of objects error `error: could not determine polymorphic type because input has type "unknown"`

Question

我一直在尝试遍历 postgres 中的对象数组。但是，我反复收到错误 error: could not determine polymorphic type because input has type "unknown"。我认为这与我传递给函数的值有关，看起来像这样。

[
  {
    "number": 1,
    "letter": "a"
  },
  {
    "number": 2,
    "letter": "b"
  }
]

函数如下。我已经制作了 ANYARRAY 类型，我认为它应该完全按照名称所暗示的那样进行。我不介意有更具体的选项可用。

CREATE OR REPLACE FUNCTION "CheckArrayOfObjects" (
  "@arrayOfObjects"           ANYARRAY
)
RETURNS void AS
$func$
DECLARE "e" JSONB;
BEGIN
  FOR "e" IN json_array_elements("@arrayOfObjects")
  LOOP
    RAISE NOTICE 'Checking Item %', "e";
  END LOOP;
END;
$func$ LANGUAGE PLPGSQL;

我也尝试过 FOREACH，但效果并不好。我认为问题出在传递的值上，所以现在还不确定修改循环是否会做任何事情。

Answer 1

参数的类型应该是JSONB（或JSON）：

CREATE OR REPLACE FUNCTION "CheckArrayOfObjects" ("@arrayOfObjects" JSONB)
RETURNS void AS
$func$
DECLARE "e" JSONB;
BEGIN
  FOR "e" IN SELECT jsonb_array_elements("@arrayOfObjects")
  LOOP
    RAISE NOTICE 'Checking Item %', "e";
  END LOOP;
END;
$func$ LANGUAGE PLPGSQL;

使用示例：

SELECT "CheckArrayOfObjects"(
'[
  {
    "number": 1,
    "letter": "a"
  },
  {
    "number": 2,
    "letter": "b"
  }
]')

NOTICE:  Checking Item {"letter": "a", "number": 1}
NOTICE:  Checking Item {"letter": "b", "number": 2}

更新

Where do notices get logged with SQL?

取决于服务器配置参数log_min_messages (enum)

What is the type ANYARRAY for if not for arrays?

它适用于 Postgres 数组类型，例如text[]、int[] 等 Json 数组不是 Postgres 数组，参见

Postgres array of objects error `error: could not determine polymorphic type because input has type "unknown"`

Postgres array of objects error `error: could not determine polymorphic type because input has type "unknown"`

arrays

postgresql

json

plpgsql

jsonb