Re: Query blobs in clojure.contrib.sql?
This is exactly what I was looking for!
Early Christmas for me.
Thank you Santa...e...John
On Dec 1, 2:04 am, John Harrop wrote:
> On Mon, Nov 30, 2009 at 9:57 PM, Base wrote:
> > Hi
>
> > I have a database that has a table with complex java objects stored in
> > a binary field.
>
> > In java i would do something like:
>
> > protected Object read(byte[] buf){
> > Object obj = null;
> > if (buf==null) return obj;
> > try {
> > ObjectInputStream objectIn =
> > new ObjectInputStream(
> > new ByteArrayInputStream(buf));
> > obj = objectIn.readObject();
> > } catch (IOException e){
> > ...
> > }
> > return obj;
> > }
>
> > I am stumped as to how to handle this sort of syntax in clojure.
>
> > (defn select-test2[]
> > (with-connection db
> > (with-query-results res ["SELECT BIN_OBJ FROM MYTABLE where ID
> > =16000254"] (doall res
>
> There seems to be some sort of disconnect here. The second piece of code
> queries a database and realizes the result seq. The first extracts a
> serialized Java object from a byte buffer. The missing link would be however
> one extracts a BLOB from the result seq in the form of a Java byte buffer.
>
> As for the clojure syntax, that for obtaining the byte buffer is unknown,
> but presumably involves Java interop. That for the deserialization is
> straightforward:
>
> (if-not (nil? byte-buffer)
> (with-open [object-in (ObjectInputStream.
> (ByteArrayInputStream. byte-buffer))]
> (.readObject object-in)))
>
> (Just four lines of Clojure code, versus 11 of Java. :))
>
> (If your Java try block didn't just clean up the streams but also e.g.
> logged the error you'll need a try form added, e.g.
>
> (if-not (nil? byte-buffer)
> (try
> (with-open [object-in (ObjectInputStream.
> (ByteArrayInputStream. byte-buffer))]
> (.readObject object-in))
> (catch (Throwable t)
> (log-error t)
> (throw t
>
> or perhaps more specific handling of particular exceptions.)- Hide quoted
> text -
>
> - Show quoted text -
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Re: Query blobs in clojure.contrib.sql?
On Mon, Nov 30, 2009 at 9:57 PM, Base wrote:
> Hi
>
> I have a database that has a table with complex java objects stored in
> a binary field.
>
> In java i would do something like:
>
> protected Object read(byte[] buf){
> Object obj = null;
> if (buf==null) return obj;
> try {
>ObjectInputStream objectIn =
> new ObjectInputStream(
> new ByteArrayInputStream(buf));
>obj = objectIn.readObject();
>} catch (IOException e){
> ...
> }
> return obj;
> }
>
>
> I am stumped as to how to handle this sort of syntax in clojure.
>
> (defn select-test2[]
> (with-connection db
>(with-query-results res ["SELECT BIN_OBJ FROM MYTABLE where ID
> =16000254"] (doall res
>
There seems to be some sort of disconnect here. The second piece of code
queries a database and realizes the result seq. The first extracts a
serialized Java object from a byte buffer. The missing link would be however
one extracts a BLOB from the result seq in the form of a Java byte buffer.
As for the clojure syntax, that for obtaining the byte buffer is unknown,
but presumably involves Java interop. That for the deserialization is
straightforward:
(if-not (nil? byte-buffer)
(with-open [object-in (ObjectInputStream.
(ByteArrayInputStream. byte-buffer))]
(.readObject object-in)))
(Just four lines of Clojure code, versus 11 of Java. :))
(If your Java try block didn't just clean up the streams but also e.g.
logged the error you'll need a try form added, e.g.
(if-not (nil? byte-buffer)
(try
(with-open [object-in (ObjectInputStream.
(ByteArrayInputStream. byte-buffer))]
(.readObject object-in))
(catch (Throwable t)
(log-error t)
(throw t
or perhaps more specific handling of particular exceptions.)
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Query blobs in clojure.contrib.sql?
Hi
I have a database that has a table with complex java objects stored in
a binary field.
In java i would do something like:
protected Object read(byte[] buf){
Object obj = null;
if (buf==null) return obj;
try {
ObjectInputStream objectIn =
new ObjectInputStream(
new ByteArrayInputStream(buf));
obj = objectIn.readObject();
} catch (IOException e){
...
}
return obj;
}
I am stumped as to how to handle this sort of syntax in clojure.
(defn select-test2[]
(with-connection db
(with-query-results res ["SELECT BIN_OBJ FROM MYTABLE where ID
=16000254"] (doall res
Any thoughts would be *most* appreciated.
Thanks
Base
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