R help - Sep 2014 - Detect expired RSQLiteConnection?

Is there a test for an expired RSQLiteConnection?  For example, if I run

library(RSQLite)
f <- tempfile()
con <- dbConnect(SQLite(), f)
dbDisconnect(con)
con

then I get
> con
<Expired SQLiteConnection: DBI CON (11737, 2)>

and most operations using it give errors. (In my case I have a
persistent connection object, but if I save the workspace and then
reload it, I get the expired connection.) I'd like to detect this case.
 Do I need to use try(), or parse the result of printing it?

Duncan Murdoch

On Sep 2, 2014, at 5:32 AM, Duncan Murdoch wrote:
> Is there a test for an expired RSQLiteConnection?  For example, if I run
> 
> library(RSQLite)
> f <- tempfile()
> con <- dbConnect(SQLite(), f)
> dbDisconnect(con)
> con
> 
> then I get
> 
>> con
> <Expired SQLiteConnection: DBI CON (11737, 2)>
> 
> and most operations using it give errors. (In my case I have a
> persistent connection object, but if I save the workspace and then
> reload it, I get the expired connection.) I'd like to detect this case.
> Do I need to use try(), or parse the result of printing it?
> 
Noodling through the S4 and then the S3 code I found:

?isIdCurrent as the test in `sqliteCloseConnection`
> 
-- 

David Winsemius
Alameda, CA, USA

DBI 0.3 (just released to CRAN) includes a new generic, dbIsValid(),
for exactly this purpose. Unfortunately no packages implement a method
for it yet, but eventually it will be the right way to detect this
problem.

(I'm now the maintainer for RSQLite, so I added this to my to do list:
https://github.com/rstats-db/RSQLite/issues/36. Pull requests are very
welcome!)

Hadley

On Tue, Sep 2, 2014 at 7:32 AM, Duncan Murdoch <murdoch.duncan at
gmail.com> wrote:
> Is there a test for an expired RSQLiteConnection?  For example, if I run
>
> library(RSQLite)
> f <- tempfile()
> con <- dbConnect(SQLite(), f)
> dbDisconnect(con)
> con
>
> then I get
>
>> con
> <Expired SQLiteConnection: DBI CON (11737, 2)>
>
> and most operations using it give errors. (In my case I have a
> persistent connection object, but if I save the workspace and then
> reload it, I get the expired connection.) I'd like to detect this case.
>  Do I need to use try(), or parse the result of printing it?
>
> Duncan Murdoch
>
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-- 
http://had.co.nz/