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<p class=MsoNormal>Good afternoon Chaps,<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I'm looking for your advice on the best way to handle
exceptions on a query and commit. Within my application I have a universal
database connection which gets injected into objects which require database
access, I then use this connection to create cursors, run queries and commit
the changes to the database. Does that sounds like a good approach?<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Take a look at this query below:<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New";color:black'>
</span><span style='font-size:10.0pt;font-family:"Courier New";color:silver'>#
Create the Cursor for the database.</span><span style='font-size:10.0pt;
font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New";color:black'>
cursor = <i>self</i>.datasource.cursor()</span><span style='font-size:10.0pt;
font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New";color:black'>
</span><span style='font-size:10.0pt;font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New";color:black'>
</span><span style='font-size:10.0pt;font-family:"Courier New";color:silver'>#
Run the insert query to create the entry.</span><span style='font-size:10.0pt;
font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New";color:black'>
cursor.execute(</span><i><span style='font-size:10.0pt;font-family:"Courier New";
color:#00AA00'>"""</span></i><span style='font-size:10.0pt;
font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><i><span style='font-size:10.0pt;
font-family:"Courier New";color:#00AA00'>
INSERT INTO message (</span></i><span style='font-size:10.0pt;font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><i><span style='font-size:10.0pt;
font-family:"Courier New";color:#00AA00'>
message_id,</span></i><span style='font-size:10.0pt;font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><i><span style='font-size:10.0pt;
font-family:"Courier New";color:#00AA00'>
name,</span></i><span style='font-size:10.0pt;font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><i><span style='font-size:10.0pt;
font-family:"Courier New";color:#00AA00'>
checksum,</span></i><span style='font-size:10.0pt;font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><i><span style='font-size:10.0pt;
font-family:"Courier New";color:#00AA00'>
created, </span></i><span style='font-size:10.0pt;font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><i><span style='font-size:10.0pt;
font-family:"Courier New";color:#00AA00'>
modified</span></i><span style='font-size:10.0pt;font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><i><span style='font-size:10.0pt;
font-family:"Courier New";color:#00AA00'>
) </span></i><span style='font-size:10.0pt;font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><i><span style='font-size:10.0pt;
font-family:"Courier New";color:#00AA00'>
VALUES (</span></i><span style='font-size:10.0pt;font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><i><span style='font-size:10.0pt;
font-family:"Courier New";color:#00AA00'>
%s,</span></i><span style='font-size:10.0pt;font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><i><span style='font-size:10.0pt;
font-family:"Courier New";color:#00AA00'>
%s,</span></i><span style='font-size:10.0pt;font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><i><span style='font-size:10.0pt;
font-family:"Courier New";color:#00AA00'>
%s,</span></i><span style='font-size:10.0pt;font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><i><span style='font-size:10.0pt;
font-family:"Courier New";color:#00AA00'>
now(),
</span></i><span style='font-size:10.0pt;font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><i><span style='font-size:10.0pt;
font-family:"Courier New";color:#00AA00'>
now()</span></i><span style='font-size:10.0pt;font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><i><span style='font-size:10.0pt;
font-family:"Courier New";color:#00AA00'>
)"""</span></i><span style='font-size:10.0pt;font-family:"Courier New";
color:black'>, (<i>self</i>.message_id, <i>self</i>.name, <i>self</i>.checksum))</span><span
style='font-size:10.0pt;font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'><o:p> </o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New";color:black'>
</span><span style='font-size:10.0pt;font-family:"Courier New";color:silver'>#
Commit the change to the database.</span><span style='font-size:10.0pt;
font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New";color:black'>
<i>self</i>.datasource.commit()</span><span style='font-size:10.0pt;font-family:
"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New";color:black'>
</span><span style='font-size:10.0pt;font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New";color:black'>
</span><span style='font-size:10.0pt;font-family:"Courier New";color:silver'>#
Close the cursor for the database.</span><span style='font-size:10.0pt;
font-family:"Courier New"'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New";
color:black'> cursor.close()</span><o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Now to add some exception handling to that query, do I
simply wrap the whole code block up in a try/except, and handle any exceptions?
or should I be doing a nested try/except which only runs the commit method is
the execute runs without exception, and likewise only closes the cursor if it
opens successfully?<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I'd really appreciate your advice on this, I'm relatively
new to the world of db implementation using the dbapi and want to make this as
water tight as possible.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Many thanks,<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Heston James.<o:p></o:p></p>
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