Postgresql CHECK IN列表约束的自定义错误消息 [英] Custom error message for Postgresql CHECK IN list constraint

问题描述

我想为Postgres CHECK IN违规创建更具体的错误消息。因此，例如，违反了列上的以下CHECK约束：

I would like to create a more specific error message for Postgres CHECK IN violations. So for example a violation of the following CHECK constraint on a column:

management_zone varchar(15) NOT NULL CHECK (management_zone IN ('Marine', 'Terrestrial') ),

应该返回自定义错误消息，例如： 提示：请检查拼写。仅允许输入的是：'Marine'，'Terrestrial'。

should return a custom error message such as ie.: "Hint: Check spelling. Only allowed inputs are: 'Marine', 'Terrestrial'.

到目前为止，我所看到的最佳解决方案是使用以下错误消息来解决此问题：检查约束的名称，即

The best solution I have seen so far solves it by using the error message as the name of the check constraint, ie

ADD CONSTRAINT c_managementzone_@Check_spelling._Only_allowed_inputs_are:_'Marine',_'Terrestrial' CHECK (management_zone IN ('Marine', 'Terrestrial') ),

，然后应用可修复的函数

and then applying a function that fixes the error message after the @ sign by replacing the underscores with space to make it more readable. The function is then called using a try and catch statement.

该代码是@符号后的错误消息，方法是使用下划线替换下划线以使其更具可读性，然后使用try和catch语句调用该函数。在我不熟悉的t-sql中，我也不知道足够的PL / pgSQL能够转换和复制它。因此，我想知道是否有人可以建议在postgres中进行类似的操作。使用功能和触发器？

This code however is in t-sql which I am unfamiliar with, and I also don't know enough PL/pgSQL to be able to convert and replicate it. I therefore wonder if anyone can suggest how something similar can be done in postgres, ex. using a function and a trigger?

t-sql代码和解释可从此处获得，我将其复制粘贴到下面：
https：//social.technet。 microsoft.com/wiki/contents/articles/29187.t-sql-error-handling-for-check-constraints.aspx

The t-sql code and explanation is available from here and I copy paste it below: https://social.technet.microsoft.com/wiki/contents/articles/29187.t-sql-error-handling-for-check-constraints.aspx

CREATE FUNCTION dbo.ufnGetClearErrorMessage2()
RETURNS NVARCHAR(4000)
AS
BEGIN
    DECLARE @Msg NVARCHAR(4000) = ERROR_MESSAGE() ;
    DECLARE @ErrNum INT = ERROR_NUMBER() ;
    DECLARE @ClearMessage NVARCHAR(4000) ;
    IF @ErrNum = 547
        BEGIN
            /*--how to find @ClearMessage:
            SELECT @msg ,
               CHARINDEX('@', @msg) ,
               RIGHT(@msg, LEN(@msg) - CHARINDEX('@', @msg)) ,
               CHARINDEX('"', RIGHT(@msg, LEN(@msg) - CHARINDEX('@', @msg))) ,
               LEFT(RIGHT(@msg, LEN(@msg) - CHARINDEX('@', @msg)), CHARINDEX('"', RIGHT(@msg, LEN(@msg) - CHARINDEX('@', @msg))) - 1 ) ,
               REPLACE(LEFT(RIGHT(@msg, LEN(@msg) - CHARINDEX('@', @msg)), CHARINDEX('"', RIGHT(@msg, LEN(@msg) - CHARINDEX('@', @msg))) - 1 ), '_', SPACE(1)) + '.'
        */
            SELECT @ClearMessage = @Msg + CHAR(13) +
            REPLACE(LEFT(RIGHT(@msg, LEN(@msg) - CHARINDEX('@', @msg)), CHARINDEX('"', RIGHT(@msg, LEN(@msg) - CHARINDEX('@', @msg))) - 1 ), '_', SPACE(1)) + '.'

        END
    ELSE
        SET @ClearMessage = @Msg ;

    RETURN @ClearMessage ;
END

试一试：

BEGIN TRY
INSERT  dbo.Book
        ( BookId, WritingDate, publishDate )
VALUES  ( 1, GETDATE(), GETDATE() + 1 )
END TRY
BEGIN CATCH

DECLARE @Msg NVARCHAR(4000) = dbo.ufnGetClearErrorMessage2();
THROW 60001, @Msg, 1;
END CATCH

任何忠告都值得赞赏。

推荐答案

如果您可以使用略有不同的检查约束，则可以执行以下操作：

If you can live with a slightly different check constraint, you can do the following:

创建一个函数会检查值：

Create a function that checks the values:

create function check_zone(p_input text)
  returns boolean
as
$$
declare
  l_allowed text[] := array['Marine', 'Terrestrial'];
begin
  if p_input = any(l_allowed) then 
    return true;
  end if;
  raise 'The only allowed values are: %', array_to_string(l_allowed, ', ');
end;
$$
language plpgsql
immutable;

然后使用该函数代替IN条件：

And then use that function instead of an IN condition:

create table data
(
  management_zone text not null,
  CONSTRAINT check_zone CHECK (check_zone(management_zone))
);

以下插入

insert into data values ('foo');

将导致：

错误：唯一允许的值是：海洋，陆地

ERROR: The only allowed values are: Marine, Terrestrial

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