The thing is the project that I'm intending to use web2py for is a web
application for language learners, and I need to be sure that as many
languages as possible are correctly treated by the application.
So, I don't think it would be safe to use a Russian character for
calculating the length of a field as in charlen = lambda n:
n*len('л').
I'm not an advanced Python programmer, so if I'm wrong, please correct me.
21 марта 2009 г. 17:15 пользователь Yarko Tymciurak <[email protected]> написал:
> Hi Alexei -
> Since UTF8 is variable length, and data is cheap, you can be generous.
> when a field is too short, you invariably have at least an unhappy customer
> by some measure.
> You saw your test name was not 22 bytes, but 21 ... so 2x is mildly
> conservative. You should be ok w/ something like:
> charlen = lambda n: n*len('л')
> db.define_table( 'mytable',
> ...
> SQLField( 'something', length=charlen(32) ),
> ...
>
>
> This may be a good pattern to use regardless... what do you think?
>
> Regards,
> Yarko
>
>
>
> 2009/3/21 Alexei Vinidiktov <[email protected]>
>>
>> Hi Yarko,
>>
>> Thanks for your help.
>>
>> I've tried setting the name field length to 32, and it worked fine
>> with a name such as Олег Зимний.
>>
>> It was to be expected though.
>>
>> The question is, in what units should the field length be measured -
>> bytes or characters?
>>
>> I think it should be measured in characters, because you never know
>> know many bytes a string with international characters will be. I
>> understand it may not be possible, so I'd like to know what's the
>> practical advice? Should I asign a string field double the number of
>> bytes the longest name (or other information stored in the field) can
>> have? For instance, if I want a string field to contain the maximum of
>> 20 characters, I should set it to 40 units (bytes). Is that correct?
>>
>> I think this approach is error prone, because one can forget to do so
>> every time one adds a string field to a db definition.
>>
>> 21 марта 2009 г. 15:06 пользователь Yarko Tymciurak <[email protected]>
>> написал:
>> > Hi Alexei -
>> > web2py uses UTF8 internally; this means Cyrillica will encode in 2-bytes
>> > per
>> > character
>> > (have a look
>> > at http://en.wikipedia.org/wiki/UTF-8#Rationale_behind_UTF-8.27s_design,
>> > or http://ru.wikipedia.org/wiki/UTF-8#Rationale_behind_UTF-8.27s_design)
>> >
>> > I copy/pasted "Oleg Zumniy" from your note into development copy
>> > (sqlite) of
>> > the PyCon2009 conference server...
>> >>>> s=db(db.contacts.id>0).select()
>> >>>> s[0].name
>> >
>> > '\xd0\x9e\xd0\xbb\xd0\xb5\xd0\xb3 \xd0\x97\xd0\xb8\xd0\xbc\xd0\xbd\xd0\xb8\xd0\xb9'
>> > As you can see - 2-bytes per character ...
>> > SQLField defaults are shown on p.138 - 'string', length=32 is default.
>> > Try
>> > that, see if that works for you.
>> > Hope that helps.
>> > Regards,
>> > Yarko
>> > 2009/3/21 Alexei Vinidiktov <[email protected]>
>> >>
>> >> Hello,
>> >>
>> >> I'm just beginning to learn web2py. I've bought the web2py manual and
>> >> am reading Chapter 1.
>> >>
>> >> I've defined a model through the admin interface:
>> >>
>> >> db = SQLDB('sqlite://storage.db')
>> >> db.define_table('contacts',
>> >> SQLField('name', 'string', length=20),
>> >> SQLField('phone', 'string', length=12))
>> >>
>> >> When I go to the admin interface to add some records, I can add names
>> >> that are written with Latin characters just fine, but when I try to
>> >> enter a name written with Cyrillic characters, I get an error that
>> >> says that the name is too long, although it is not.
>> >>
>> >> For example, if I enter the name Олег Зимний, which is 11 characters
>> >> long, I get that error.
>> >>
>> >> If I enter a short name such as Олег, the record is added fine.
>> >>
>> >> The maximum length is set to 20 in the table definition and names with
>> >> Latin characters whose length is up to 20 characters can be added
>> >> fine.
>> >>
>> >> Is it a web2py bug? If it is, can it be easily fixed?
>> >>
>> >> --
>> >> Alexei Vinidiktov
>> >>
>> >>
>> >
>> >
>> > >
>> >
>>
>>
>>
>> --
>> Alexei Vinidiktov
>>
>>
>
>
> >
>
--
Alexei Vinidiktov
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