[dancer-users] how to make sure one db connection per user

[Richard Jones]

One way, if there isn't too much info, is to store the user data in 
their session, probably safest to use a server-based session for this 
(JSON, YAML, Storable, DBIC, etc). If there is a *lot* of data this 
might not be practical, but still the query could be selective using the 
session username. This is what I do for one of my apps and it works fine.

On 21/09/2015 10:51, Dancer New wrote:
>
>
> On Fri, Sep 18, 2015 at 5:39 PM, Maxwell Carey <mcarey at ucar.edu 
> <mailto:mcarey at ucar.edu>> wrote:
>
>
>
>     On Fri, Sep 18, 2015 at 10:32 AM, WK <wanradt at gmail.com
>     <mailto:wanradt at gmail.com>> wrote:
>
>         Hi!
>
>         2015-09-18 19:09 GMT+03:00 Dancer New <dancerfan2015 at gmail.com
>         <mailto:dancerfan2015 at gmail.com>>:
>
>         > I use Dancer::Plugin::Database in my application. Each time when
>         > $dbh = DBI->connect( $c->{ dsn }, $c->{ username }, $c->{
>         password}, $c->{
>         > dbi_params })
>         > is called. does it return a new connection?
>
>         Yes, it does. But then is no point to use
>         Dancer::Plugin::Database at all.
>
>
>     To expand on this a little, with Dancer::Plugin::Database, you
>     should be using the 'database' function instead of calling
>     DBI->connect. See the documentation here
>     https://metacpan.org/pod/Dancer::Plugin::Database#GETTING-A-DATABASE-HANDLE
>
>     "Calling |database| will return a connected database handle; the
>     first time it is called, the plugin will establish a connection to
>     the database, and return a reference to the DBI object. On
>     subsequent calls, the same DBI connection object will be returned,
>     unless it has been found to be no longer usable (the connection
>     has gone away), in which case a fresh connection will be obtained."
>
>
> Thanks for the explanation.
>
>
>
>         > I would like one db connection for each user, where can I
>         save the database
>         > handler?
>
>         Could you elaborate, why every user must have their own
>         connection? It
>         does not seem reasonable. Using just one connection over the
>         application is much cheaper way. When using
>         Dancer::Plugin::Database
>         you must set up connection data in config file.
>
>
>     You can define multiple connections so that database('foo') will
>     connect with one set of connection parameters and database('bar')
>     will use another. See
>     https://metacpan.org/pod/Dancer::Plugin::Database#DEFINING-MULTIPLE-CONNECTIONS
>
>     But I agree, this seems like a bad idea. What exactly are you
>     trying to do?
>
>
> I want to make sure each user only see their own data.
> So in the database, I have a procedure to set the context. By calling 
> this procedure, it records that this database session is for the 
> particular user, any subsequent queries is for the particular user.
>
> If I use the same database connection for all of the queries, when a 
> user comes in and the database set context for the user, but at the 
> same time another user comes in,  then will the database think it is 
> the previous user, and return the data of the previous user to the new 
> user?
>
> If I don't use one database connection for each user, how can I make 
> sure the database handler know which user it is dealing with?
>
> Many thanks,
> Dan
>
>
>
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-- 
Richard Jones

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