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From Zachary Zolton <>
Subject Re: User Uniqueness Validation
Date Wed, 01 Jul 2009 02:50:23 GMT
Okay, so if I'm reading this correctly, the procedure should go like this:

get next uuid
put doc (with reference to uuid)
if 409
    display email address is already taken
    put doc user_name:foobar (with reference to uuid)
    if 409
        display user name is already taken
        create user doc (with email_address and user_name)
        display success message

Thanks for your input!


On Tue, Jun 30, 2009 at 6:22 PM, Jason Davies<> wrote:
> An extension to this scheme would be to add some kind of prefix to the ID,
> in case you want to have more than one "uniqueness constraint".  So you
> might have "" and "" for
> example to avoid the two constraints interfering with each other.
> --
> Jason Davies
> On 30 Jun 2009, at 23:37, Adam Wolff wrote:
>> You can't check then act with couchdb -- there are no transactions. I
>> think
>> the only way to guarantee uniqueness is to try to put, using the natural
>> primary key as the id the of the document. We are doing this by putting a
>> document like this:{
>>   _id : "",
>>   userId : [reference_to_user_sha]
>> }
>> This way, you can tell if the email address is claimed and take it all in
>> one shot. Then it's trivial to create views which accumulate the user data
>> as well.
>> HTH - it took us a while to figure this one out.
>> A
>> On Tue, Jun 30, 2009 at 2:58 PM, Sam Bisbee <>
>> wrote:
>>> Greetings,
>>>> So, I've got a situation where I want to maintain a CouchDB database
>>>> of users that have a user name and email address. Given that the user
>>>> name needs to be unique—and is significant to my URL scheme—I've
>>>> chosen to use that as the document ID.
>>> While I don't know the full context of your situation, I would still use
>>> a
>>> generated id for users. This makes life much easier in the software's
>>> life
>>> cycle. For example, what if you want to do away with user names and just
>>> use
>>> e-mail addresses? Or you need to generically identify a user but don't
>>> have
>>> access to their user name? Now you need to re-rig your code to use a
>>> different id scheme. I've found it much easier to just take the user id
>>> generated by the index or my code's logic and use that as my primary
>>> identifier in the database. I've found this to be database agnostic.
>>>> However, I'd also like to maintain uniqueness of the email addresses
>>>> across users... Any ideas about how to best accomplish this?
>>> While those with more experience than me on the Couch may have a better
>>> technique, I have always just constructed a view that outputs the users'
>>> email addresses as keys. Then I can query the view with
>>> ?key='emailInQuestion' and if the returned array has any results then the
>>> e-mail is already registered. This also scales nicely with cases where
>>> users
>>> can have more than one email associated to them.
>>> --
>>> Sam Bisbee

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