Rails - Mar 2007 - Generic validation / maxlength off column[colname].limit ?

I''m currently using validates_length_of to guard against buffer
overruns in the model and using js max_length in the views to try to "head
it off at the pass."  There are two problems with the approach I''m
currently using.

First is that the length value is hardcoded in both the model and view so that
if I change the length of the string in the database, I have to change the value
in both the model validations and any view that uses the string.

Second is that, in the model, I''ve got to list each attribute I want to
validate individually.  Some of the models have a lot of attributes.

I''ve looked at using validates_each and that could help a little with
the second problem, but it''s still unwieldly listing each attribute.

For the model side of this, I''m thinking of writing a generic
validation that iterates through the attributes of a model object on a save or
update and if it''s a string or char type, get it''s size /
limit from the table column attributes and validate against that.  That would
seem to give me immunity in the validation from changes in the column sizes.

For the view side, I''m thinking of a similar approach that
feed''s the maxlength with a value based, again, on the column size
rather than a hard-coded value.

Two questions.  Anybody know of something like that that already exists? 
Anybody think it''s not doable?

Thanks,
Bill
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> I''m currently using validates_length_of to guard against buffer
overruns
> in the model and using js max_length in the views to try to "head it
off
> at the pass."  There are two problems with the approach I''m
currently
> using.
>
> First is that the length value is hardcoded in both the model and view 
> so that if I change the length of the string in the database, I have to 
> change the value in both the model validations and any view that uses 
> the string.
>
> Second is that, in the model, I''ve got to list each attribute I
want to
> validate individually.  Some of the models have a lot of attributes.
>
> I''ve looked at using validates_each and that could help a little
with
> the second problem, but it''s still unwieldly listing each
attribute.
>
> For the model side of this, I''m thinking of writing a generic
validation
> that iterates through the attributes of a model object on a save or 
> update and if it''s a string or char type, get it''s size /
limit from the
> table column attributes and validate against that.  That would seem to 
> give me immunity in the validation from changes in the column sizes.
>
> For the view side, I''m thinking of a similar approach that
feed''s the
> maxlength with a value based, again, on the column size rather than a 
> hard-coded value.
>
> Two questions.  Anybody know of something like that that already exists? 
> Anybody think it''s not doable?
I can''t remember the name, but I''ve seen a plugin that will
automatically
turn your model validations into javascript validations... that would get 
you half way there...

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>> I''m currently using validates_length_of to guard against
buffer overruns
>> in the model and using js max_length in the views to try to "head
it off
>> at the pass."  There are two problems with the approach
I''m currently
>> using.
>>
>> First is that the length value is hardcoded in both the model and view
>> so that if I change the length of the string in the database, I have to
>> change the value in both the model validations and any view that uses
>> the string.
>>
>> Second is that, in the model, I''ve got to list each attribute
I want to
>> validate individually.  Some of the models have a lot of attributes.
>>
>> I''ve looked at using validates_each and that could help a
little with
>> the second problem, but it''s still unwieldly listing each
attribute.
>>
>> For the model side of this, I''m thinking of writing a generic
validation
>> that iterates through the attributes of a model object on a save or
>> update and if it''s a string or char type, get it''s
size / limit from the
>> table column attributes and validate against that.  That would seem to
>> give me immunity in the validation from changes in the column sizes.
>>
>> For the view side, I''m thinking of a similar approach that
feed''s the
>> maxlength with a value based, again, on the column size rather than a
>> hard-coded value.
>>
>> Two questions.  Anybody know of something like that that already
exists?
>> Anybody think it''s not doable?
>
> I can''t remember the name, but I''ve seen a plugin that
will automatically
> turn your model validations into javascript validations... that would get
> you half way there...
Found them.

http://agilewebdevelopment.com/plugins/enforce_schema_rules
http://agilewebdevelopment.com/plugins/client_side_validation

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Hi Philip,

Philip Hallstrom wrote:
> Found them.
> 
> http://agilewebdevelopment.com/plugins/enforce_schema_rules
> http://agilewebdevelopment.com/plugins/client_side_validation

Super!!!  Haven''t had a look yet but, worst case, that''s a big
head start!

Thanks!
Bill


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