Обсуждение: inet value validation

hello,

I want to write a function to validate an inet data type, but I figure
that postgres should already have such a function to use before
inserting values in inet type columns.
is it possible to access postgres's validation function for inet types ?
I have snooped through the catalogs but I can not find such a function.


thanks,
Razvan Radu

pgsql-general@list.coretech.ro <pgsql-general@list.coretech.ro> schrieb:

>
> hello,
>
> I want to write a function to validate an inet data type, but I figure that
> postgres should already have such a function to use before inserting values
> in inet type columns.
> is it possible to access postgres's validation function for inet types ? I
> have snooped through the catalogs but I can not find such a function.

You can try to cast a string into inet like this:

test=# select '127.0.0.255'::inet;
    inet
-------------
 127.0.0.255
(1 row)

test=# select '127.0.0.256'::inet;
ERROR:  invalid input syntax for type inet: "127.0.0.256"


Now you can write a little function to do this:

,----[  a little function  ]
| create or replace function check_ip(varchar) returns bool as $$
| declare
|         i inet;
| begin
|         i := $1::inet;
|         return 't'::bool;
|         EXCEPTION WHEN invalid_text_representation then
|                 return 'f'::bool;
| end;
| $$ language plpgsql immutable strict;
`----

You can use this function now inside a transaction.



HTH, Andreas
--
Really, I'm not out to destroy Microsoft. That will just be a completely
unintentional side effect.                              (Linus Torvalds)
"If I was god, I would recompile penguin with --enable-fly."    (unknow)
Kaufbach, Saxony, Germany, Europe.              N 51.05082°, E 13.56889°

yes, this is a good example, but I do not want to use an exception block
because of the warning present on documentation regarding exception blocks
"*Tip: * A block containing an EXCEPTION clause is significantly more
expensive to enter and exit than a block without one. Therefore, don't
use EXCEPTION without need."

I intend to use this function heavily.


Razvan Radu

Andreas Kretschmer wrote:
> pgsql-general@list.coretech.ro <pgsql-general@list.coretech.ro> schrieb:
>
>
>> hello,
>>
>> I want to write a function to validate an inet data type, but I figure that
>> postgres should already have such a function to use before inserting values
>> in inet type columns.
>> is it possible to access postgres's validation function for inet types ? I
>> have snooped through the catalogs but I can not find such a function.
>>
>
> You can try to cast a string into inet like this:
>
> test=# select '127.0.0.255'::inet;
>     inet
> -------------
>  127.0.0.255
> (1 row)
>
> test=# select '127.0.0.256'::inet;
> ERROR:  invalid input syntax for type inet: "127.0.0.256"
>
>
> Now you can write a little function to do this:
>
> ,----[  a little function  ]
> | create or replace function check_ip(varchar) returns bool as $$
> | declare
> |         i inet;
> | begin
> |         i := $1::inet;
> |         return 't'::bool;
> |         EXCEPTION WHEN invalid_text_representation then
> |                 return 'f'::bool;
> | end;
> | $$ language plpgsql immutable strict;
> `----
>
> You can use this function now inside a transaction.
>
>
>
> HTH, Andreas
>

pgsql-general@list.coretech.ro <pgsql-general@list.coretech.ro> schrieb:

>
> yes, this is a good example, but I do not want to use an exception block
> because of the warning present on documentation regarding exception blocks

No problem, i want to show a transaction-secure solution. You can use
this without the exception block, but if you got a error, a transaction
will be failed.

> Andreas Kretschmer wrote:
> >pgsql-general@list.coretech.ro <pgsql-general@list.coretech.ro> schrieb:
> >
> >>hello,

Argh. Please no silly fullquote below the text.


Andreas
--
Really, I'm not out to destroy Microsoft. That will just be a completely
unintentional side effect.                              (Linus Torvalds)
"If I was god, I would recompile penguin with --enable-fly."    (unknow)
Kaufbach, Saxony, Germany, Europe.              N 51.05082°, E 13.56889°