Re: [Q] storing JSON, problem with 'escapes'

On Fri, 2008-11-21 at 01:54 -0500, V S P wrote:
> Hi,
> I am using PHP's json_encode function on
> an array of strings
> that gives me back a JSON encoded string.
>
> Some of the elements in the string arrays have
> double quotes.  So PHP's json_encode correctly
> escapes them (according to JSON specifications)
> with \.
>
> For example here is a an array element
>
> "if( js_iop_lt(a,b) ){ VLADIKVLADIKVLADIKVLADIK("b2122") ;}"
>
> would get encoded in JSON as
>
> "if( js_iop_lt(a,b) ){ VLADIKVLADIKVLADIKVLADIK(\"b2122\") ;}"
>
> And that's correct.
> Now, the problem is that with PDO (or may be postgresql itself)
> I get
>
>
> "if( js_iop_lt(a,b) ){ VLADIKVLADIKVLADIKVLADIK(\\"b2122\\") ;}"
>
>
> and I get then the POSTGRESQL warning
>
> WARNING:  nonstandard use of \\ in a string literal at character 240
> HINT:  Use the escape string syntax for backslashes, e.g., E'\\'.

When you construct your SQL, if you are going to construct it as a
string, like:

INSERT INTO blah ( json_column )
 VALUES ( 'VLADIKVLADIKVLADIKVLADIK(\\"b2122\\")' )

You need to instead insert as:

INSERT INTO blah ( json_column )
 VALUES ( E'VLADIKVLADIKVLADIKVLADIK(\\"b2122\\")' )


The "E" in front of the string is a special PostgreSQL thing which
explains that the string is encoded with \ escaping.

See:

http://www.postgresql.org/docs/8.3/interactive/sql-syntax-lexical.html


particularly the box labelled 'caution' and the paragraph above it.

Regards,
                    Andrew McMillan.


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