Using create, update and validation

Rails
1

Hi List

When using the create and update methods, is there anyway of confirming
that the create/update method was unsuccessful- e.g. if it failed
validation? The API documentation and playing around in the console
suggest that it fails silently.

With a create, I could always check if the object’s id has been set -
but what would one do on an update?

Any help appreciated

Rory

2

On 10 Apr 2008, at 13:28, Rory McKinley wrote:

but what would one do on an update?
They return true/false. the ! variants raise an exception instead. You
can always call the valid? method to see if an object’s validations
pass.

Fred

3

simply check if save or update_attributes returns true:

if @alert.save
flash[:notice] = ‘cool, its ok’
redirect_to wherever
else
flash[:notice] = ‘oops!’
end

same for update_attributes
and of course you can use render :template =>
instead of redirect or redirect in case of errors

another way would be to check the errors object of the record

if @alert.errors.size > 0 …
the error object is handy anyway, since it will contain all those errors
from your validations

4

Thorsten M. wrote:

if @alert.errors.size > 0 …
the error object is handy anyway, since it will contain all those errors
from your validations

Thanks Thorsten

So , would it be recommended to use this method (checking @alert.errors)
versus catching an exception from the save! or create! or update! ?

Thanks

Rory

5

So , would it be recommended to use this method (checking @alert.errors)
versus catching an exception from the save! or create! or update! ?

we mostly use the “if @alert.save then” version
Freds way with the exceptions is good too of course

just a matter of taste (or maybe Fred can enlighten us, if it has
additional advantages). i just like to handle errors where they happen
to be and with the rescue handling for exceptions you end up with a bit
more code, i think

i mentioned the errors object mainly because it’s another alternative
and useful for other purposes (show errors to the user, logger.info
errors for debugging)

6

Thorsten M. wrote:

if @alert.errors.size > 0 …
the error object is handy anyway, since it will contain all those errors
from your validations

One more question :wink: - is there anyway that the method could have
completed and produced errors? Or is errors.size > 1 a guarantee that
the operation failed?

R

7

Frederick C. wrote:

On 10 Apr 2008, at 13:28, Rory McKinley wrote:

With a create, I could always check if the object’s id has been set -
but what would one do on an update?

They return true/false. the ! variants raise an exception instead. You
can always call the valid? method to see if an object’s validations
pass.

Fred

Hi Fred

Thanks for that - wasn’t aware there is a create! and update!. Just a
note - according to the api docs:

create(attributes = nil)

Creates an object (or multiple objects) and saves it to the database, if
validations pass. The resulting object is returned whether the object
was saved successfully to the database or not.

But I will just catch the exception from create! and update!.

Thanks for the help