Re: [HACKERS] [PATCH] Generic type subscripting
| От | Dmitry Dolgov |
|---|---|
| Тема | Re: [HACKERS] [PATCH] Generic type subscripting |
| Дата | |
| Msg-id | 20210119142514.nkevvvf7a2ux4553@localhost обсуждение исходный текст |
| Ответ на | Re: [HACKERS] [PATCH] Generic type subscripting ("Dian M Fay" <dian.m.fay@gmail.com>) |
| Ответы |
Re: [HACKERS] [PATCH] Generic type subscripting
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| Список | pgsql-hackers |
> On Thu, Jan 14, 2021 at 12:02:42PM -0500, Dian M Fay wrote: > > Other than that, since I've already posted the patch for returning an > > error option, it seems that the only thing left is to decide with which > > version to go. > > The trigger issue (which I did verify) makes the "no update" option > unworkable imo, JavaScript's behavior notwithstanding. But it should be > called out very clearly in the documentation, since it does depart from > what people more familiar with that behavior may expect. Here's a quick > draft, based on your v44 patch: > > <para> > <type>jsonb</type> data type supports array-style subscripting expressions > to extract or update particular elements. It's possible to use multiple > subscripting expressions to extract nested values. In this case, a chain of > subscripting expressions follows the same rules as the > <literal>path</literal> argument in <literal>jsonb_set</literal> function, > e.g. in case of arrays it is a 0-based operation or that negative integers > that appear in <literal>path</literal> count from the end of JSON arrays. > The result of subscripting expressions is always of the jsonb data type. > </para> > <para> > <command>UPDATE</command> statements may use subscripting in the > <literal>SET</literal> clause to modify <type>jsonb</type> values. Every > affected value must conform to the path defined by the subscript(s). If the > path cannot be followed to its end for any individual value (e.g. > <literal>val['a']['b']['c']</literal> where <literal>val['a']</literal> or > <literal>val['b']</literal> is null, a string, or a number), an error is > raised even if other values do conform. > </para> > <para> > An example of subscripting syntax: Yes, makes sense. I've incorporated your suggestion into the last patch, thanks.
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