Re: JSON manipulation functions

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.

regards, tom lane