Message-ID: <4c602ca2-2c1a-420c-bbf2-906d65c93e77@postgresfriends.org>
Date: Tue, 22 Jul 2025 14:45:42 +0200
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Subject: Re: CAST(... ON DEFAULT) - WIP build on top of Error-Safe User
 Functions
From: Vik Fearing <vik@postgresfriends.org>
To: jian he <jian.universality@gmail.com>
Cc: Corey Huinker <corey.huinker@gmail.com>,
 Isaac Morland <isaac.morland@gmail.com>, pgsql-hackers@lists.postgresql.org
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On 22/07/2025 14:26, Vik Fearing wrote:
> The <cast error behavior> is:
>
> <cast error behavior> ::=
>     ERROR
>   | NULL
>   | DEFAULT <value expression>
>
> but I am planning on removing the NULL variant in favor of having the 
> <value expression> be a <contextually typed value specification>.  So 
> it would be either ERROR ON CONVERSION ERROR (postgres's current 
> behavior), or DEFAULT NULL ON CONVERSION ERROR. 


Sorry, I meant <implicitly typed value specification>.


The point being that CAST(ARRAY['1', '2', 'three'] AS INTEGER ARRAY 
DEFAULT NULL ON CONVERSION ERROR) will give you (CAST NULL AS INTEGER 
ARRAY) and *not* ARRAY[1, 2, NULL].

-- 

Vik Fearing