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Subject: Re: Error-safe user functions
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To: Andrew Dunstan <andrew@dunslane.net>, Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robert Haas <robertmhaas@gmail.com>,
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From: Vik Fearing <vik@postgresfriends.org>
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On 12/4/22 17:21, Andrew Dunstan wrote:
> 
> More generally, I can see uses for error free
> casts, something like, say CAST(foo AS bar ON ERROR blurfl)

What I am proposing for inclusion in the standard is basically the same 
as what JSON does:

<cast specification> ::=
CAST <left paren>
     <cast operand> AS <cast target>
     [ FORMAT <cast template> ]
     [ <cast error behavior> ON ERROR ]
     <right paren>

<cast error behavior> ::=
     ERROR
   | NULL
   | DEFAULT <value expression>

Once/If I get that in, I will be pushing to get that syntax in postgres 
as well.
-- 
Vik Fearing