#34961 closed Cleanup/optimization (wontfix)
Add a max_length parameter to EmailValidator
Reported by: | jecarr | Owned by: | nobody |
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Component: | Core (Other) | Version: | 4.2 |
Severity: | Normal | Keywords: | |
Cc: | Mariusz Felisiak | Triage Stage: | Unreviewed |
Has patch: | no | Needs documentation: | no |
Needs tests: | no | Patch needs improvement: | no |
Easy pickings: | no | UI/UX: | no |
Description
- I was using EmailValidator on a string
- It wasn't on an EmailField (which has a default max-length of 254)
- But I did want some consistency with EmailFields I have elsewhere in my application
- The EmailValidator allows a max-length of 320 (as is mentioned in the docs too)
- Apologies if I've misunderstood design-reasons around this, but I wondered if we could have in EmailValidator a max_length property?
- So if the 320-max-length is intentional, have EmailValidator's init function take
message=None, code=None, allowlist=None, max_length=320
as its default parameters. And then use a propertymax_length
in the length-check.
Change History (9)
comment:1 by , 13 months ago
Resolution: | → wontfix |
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Status: | new → closed |
follow-up: 3 comment:2 by , 13 months ago
Thanks for the quick reply and solution!
You are correct with my use case and your solution would apply to my scenario. (I'm validating a non-Django-Field variable, a string.)
I initially raised the ticket because EmailField
has a max-length of 254 and EmailValidator
has a max-length of 320. (I am aware this is not a bug as all is still working.)
My intention was to have consistency with these two so within the Django codebase - regardless of my codebase/other applications - it does not look like two different max-lengths for email addresses are suggested. Additionally, I thought of others who may also want consistency with having max-lengths of 254 elsewhere in their application only to use Django's EmailValidator separately (not on an EmailField) to find longer email addresses accepted.
I did wonder if the two different max-lengths were unintentional and thought an approach would be to drop the EmailValidator max-length to match that of EmailField's max-length or vice-versa. But I appreciate this could cause breaking changes to existing applications hence my initial suggestion.
As this is now a wontfix and for my understanding of the codebase, I'll ask why the two different max-lengths for email addresses? Is it because with Fields we want to be stricter with max-lengths?
Blocked by SpamBayes but wanted to add a quick comment to say:
I don't have the exact answer for "why the two different max-lengths for email addresses" but I can share some facts:
Thanks Natalia for your quick and detailed reply.
As much as I see a difference, I'll keep in mind there may be design choices around it.
Much appreciated on your breakdown on Fields and Validators, it's helped me understand more about them and existing design choices around them.
comment:3 by , 13 months ago
Cc: | added |
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Replying to jecarr:
I did wonder if the two different max-lengths were unintentional and thought an approach would be to drop the EmailValidator max-length to match that of EmailField's max-length or vice-versa. But I appreciate this could cause breaking changes to existing applications hence my initial suggestion.
As this is now a wontfix and for my understanding of the codebase, I'll ask why the two different max-lengths for email addresses? Is it because with Fields we want to be stricter with max-lengths?
Thank you for reaching out after you noticed the different max lengths allowed for the EmailField
and the EmailValidator
. I don't have the exact answer for "why the two different max-lengths for email addresses" but I can share some facts:
- The validator
EmailValidator
is a generic email validator that is used to validate email addresses using regular expressions. Recently, the maximum allowed length for validating a email was limited to 320 chars following a security release from July to prevent potential DoS attacks when validating extremely long strings.
- The form field
EmailField
is an abstraction of an HTML input, basically a char field represented as<input type="email" maxlength="...>
. The defaultmax_length
for this field was set to 320 in the same security release I mentioned above (before that,max_length
was optional and unset for this field).
- The model field
EmailField
is just aCharField
with a defaultmax_length
(254 as you noticed) and a configured validator (EmailValidator
). I can see how this difference in the maximum allowed length raises questions.
So, in all honesty, when I closed the ticket yesterday I wasn't considering the two EmailField
s (the model and the form fields). Now that I write this summary, and that I see that the form field's max_length
was changed to match the length of the validator but not the model field, I do wonder if we should. I'll cc Mariusz to see what he thinks since he implemented the original 320 char limit.
Glad you asked more questions about this!
comment:4 by , 10 months ago
Resolution: | wontfix |
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Status: | closed → new |
follow-up: 6 comment:5 by , 10 months ago
Resolution: | → wontfix |
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Status: | new → closed |
The default maximum length of an email is 320 characters per RFC 3696 section 3, that's why EmailValidator
that checks if string is an email uses this boundary. There is no need to add max_length
argument. If you want to use a lower value you should add MaxLengthValidator
that Django will add automatically when you define max_length
on model fields.
We could consider changing the default to 254
characters because it was changed in RFC 5321, but this ticket is about adding max_length
to the validator, so it's "wontix" for me.
follow-up: 7 comment:6 by , 10 months ago
Replying to Mariusz Felisiak:
We could consider changing the default to
254
characters because it was changed in RFC 5321, but this ticket is about addingmax_length
to the validator, so it's "wontix" for me.
Mariusz, I checked the RFC5321 and as per my reading, the recommendation is: for the local part of the email address (before the @
symbol), no more than 64 characters long. For the domain part, no more than 255 characters. That adds up to 319 plus the @
sign, so 320chars as you already added to the EmailValidator
. Where is it that the max length was changed to 254?
comment:7 by , 10 months ago
Replying to Natalia Bidart:
Mariusz, I checked the RFC5321 and as per my reading, the recommendation is: for the local part of the email address (before the
@
symbol), no more than 64 characters long. For the domain part, no more than 255 characters. That adds up to 319 plus the@
sign, so 320chars as you already added to theEmailValidator
. Where is it that the max length was changed to 254?
Yes, but a total size limit is defined in 4.5.3.1.3:
The maximum total length of a reverse-path or forward-path is 256 octets (including the punctuation and element separators).
RFC 3696 was corrected here.
Hello, thank you for your report.
I'm not sure I understand your use case. Is it that you are not using
EmailField
but you do use theEmailValidator
in other type of field? And if so, you'd like to set a length smaller than 320 chars?If that's correct, you could define a subclass of
EmailValidator
and check for the smaller value:I'll be closing this ticket as wontfix following the Ticket Triaging policy, but if I'm not understanding your use case properly, please provide more details so we can re-asses. A small Django project as a example would be great, or at least models showcasing the use case.
Thanks!