with-connection

[Stuart Campbell]

Hello,

The README at states:

"You can omit the connection altogether. In that case, actions will use the connection bound by with-connection or the default one."

However, if I do this:

(ns foo
(:use [clojure.java.jdbc :only [with-connection]]
[lobos.core :only [create]]
[lobos.schema :only [table integer]]
[foo.config :only [db]]))

(with-connection db
(create (table :foo (integer :bar)))

I get this exception:

net.sf.log4jdbc.ConnectionSpy cannot be cast to clojure.lang.IPersistentCollection
[Thrown class java.lang.ClassCastException]

clojure.core$conj.invoke(core.clj:83)
clojure.core$merge$fn__3879.invoke(core.clj:2629)
clojure.core$reduce1.invoke(core.clj:879)
clojure.core$reduce1.invoke(core.clj:870)
clojure.core$merge.doInvoke(core.clj:2629)
clojure.lang.RestFn.invoke(RestFn.java:421)
lobos.internal$optional_cnx_or_schema.invoke(internal.clj:82)
lobos.core$create_STAR_.doInvoke(core.clj:119)
clojure.lang.RestFn.invoke(RestFn.java:423)
...

Am I misunderstanding something?

Thanks,
Stuart

[Stuart Campbell]

I should mention that the equivalent clojure.java.jdbc call works fine, i.e.:

  (use '[clojure.java.jdbc :only [with-connection create-table]])

  (with-connection db
    (create-table :foo [:bar "integer"]))

and that I'm using 1.0.0-SNAPSHOT with Clojure 1.3.

[Nicolas Buduroi]

Yes, this is definitely a bug, I'll have a look at it later today.

On Feb 7, 3:29 am, Stuart Campbell <stuart.william.campb...@gmail.com>
wrote:

> I should mention that the equivalent clojure.java.jdbc call works fine,
> i.e.:
>
>   (use '[clojure.java.jdbc :only [with-connection create-table]])
>
>   (with-connection db
>     (create-table :foo [:bar "integer"]))
>
> and that I'm using 1.0.0-SNAPSHOT with Clojure 1.3.
>

> On 6 February 2012 23:32, Stuart Campbell <stuart.william.campb...@gmail.com

[Nicolas Buduroi]

This will take more time to fix than I thought. The java.jdbc connectivity API has changed quite a bit and accept more types of connections. I've made a rather poor design decision by assuming the db-spec would always be a map, so lobos connectivity will need some major changes. I'll see what I can do this week-end.

In the meantime could you provide the way you create the db-spec you're using. I see from the error message that it is a wrapper around a connection and I still don't get how java.jdbc handle that case, I'll need to do more research.

[Stuart Campbell]

Hi Nicolas,

java.jdbc doesn't do anything special with the wrapper. I'm using log4jdbc, which handles the proxying automatically.

I get the same result when using the underlying Derby driver, which would be defined like so:

(def db {:classname "org.apache.derby.jdbc.EmbeddedDriver"
         :subprotocol "derby"
         :subname "c:/temp/derby"
         :create true})

Thanks,
Stuart

[Nicolas Buduroi]

Well, that is strange. I wasn't able to fully test Lobos with Derby because it isn't supported yet (I'll probably do that this weekend) but I was able to get to the compiler and the derby files were created. Can try out with H2 to see if you get the same problem?

[Stuart Campbell]

I just tried it, and I do get the same problem. I've traced the problem through the source below, just to make sure we're looking at the same version of the code.

In lobos.internal:

(defn optional-cnx-or-schema [args]
  (let [[cnx-or-schema args]
        (optional #(or (schema/schema? %)
                       (and (-> % schema/definition? not)
                            (conn/connection? %))) args)
        args* args
        schema (when (schema/schema? cnx-or-schema) cnx-or-schema)
        cnx (or (conn/find-connection)
                (-> schema :options :db-spec)
                (when-not schema cnx-or-schema)
                :default-connection)
        db-spec (merge (conn/get-db-spec cnx)
                       (when schema
                         {:schema (-> schema :sname name)}))]
    [db-spec schema args]))

conn/find-connection returns something like #<JdbcConnection conn9: url=jdbc:h2:tmp/h2 user=>. This goes into conn/get-db-spec and comes out unchanged:

(defn get-db-spec
  "Returns the associated db-spec or itself. *For internal use*."
  [& [connection-info]]
  (let [connection-info (or connection-info :default-connection)]
    (or (:db-spec sqlint/*db*)
        (if (keyword? connection-info)
          (-> @global-connections connection-info :db-spec)
          connection-info))))

 which causes the exception in the call to (merge).

Thanks for looking into this. I didn't realise Derby wasn't supported yet - whoops!

Regards,
Stuart

[Nicolas Buduroi]

Ok, I got it! You are using the java.jdbc version of `with-connection`, while I was refering to the `lobos.connectivity/with-connection` macro. I updated the readme to be more precise.

Also I'm not sure I'll get the Derby support working today finally.

[Stuart Campbell]

Ah, that's it! Thanks for your help.