Re: JSON manipulation functions

2010/5/14 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> On Thu, May 13, 2010 at 9:47 PM, Joseph Adams
>> <joeyadams3(dot)14159(at)gmail(dot)com> wrote:
>>> [] retrieves a value of a JSON array/object by (one-based) index.  In
>>> other words, value[n] is equivalent to selecting the nth row of
>>> json_values(value) (provided value is of type JSON).  Examples:
>>>
>>> SELECT ('[1,2,3,4]'::JSON)[3]
>>> -- Result is '3'::JSON
>>>
>>> SELECT ('{"a": 1, "b": 2, "c": 3, "d": 4}'::JSON)[3]
>>> -- Result is '3'::JSON
>
>> I think some kind of array deference and object deference mechanism is
>> absolutely, positively 100% required.  I don't know whether the
>> particular syntax you've proposed here is best or whether we should
>> pick another syntax or just use function notation, but I think we
>> definitely need *something*.
>
> Trying to use array notation on something that isn't a SQL array type
> is guaranteed to be a mess.  I strongly recommend that you not attempt
> that.  Just define a function for it.

I agree. Maybe you can implement cast to hstore datatype.

Regards

Pavel Stehule

>
>                        regards, tom lane
>
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