https://pfspipe.ipmu.jp/jira This file is an XML representation of an issue en-us 8.3.4 803005 13-09-2019 https://pfspipe.ipmu.jp/jira/browse/INSTRM-125 Instrument control development <p>pfs@ics-arch:/simdata/ics-arch-201701/products/Linux64/ics_archiver/master-ga619cf6fd9$ ./bin/archiveServer.py <br/> Running ./bin/archiveServer.py as PID 22621<br/> Starting archive server with output to /simdata/ics-arch-201701//logs/actors/archiver/archiver-22621<br/> importing postgres dbapi module psycopg2<br/> reply_raw<br/> Traceback (most recent call last):<br/> File "./bin/archiveServer.py", line 196, in &lt;module&gt;<br/> main()<br/> File "./bin/archiveServer.py", line 193, in main<br/> startServer(options)<br/> File "./bin/archiveServer.py", line 69, in startServer<br/> archiver.database.init(options)<br/> File "/simdata/ics-arch-201701/products/Linux64/ics_archiver/master-ga619cf6fd9/python/archiver/database.py", line 105, in init<br/> print "database: table %s contains %d rows" % (tableName,tableRows)<br/> TypeError: %d format: a number is required, not NoneType</p> <p>max() will return null value but not 0 for no row inserted. need to add handler when no row exists.</p> INSTRM-125

Archiver dies when table does not have any row

Bug Major Done Done cloomis shimono Thu, 15 Jun 2017 08:13:18 +0000 Wed, 21 Jun 2017 13:18:28 +0000 Wed, 21 Jun 2017 13:18:28 +0000 ics_archiver 0 3 <p>Sorry for that, I've been a bit careless. <br/> I've looked at your commit on github:</p> <div class="preformatted panel" style="border-width: 1px;"><div class="preformattedContent panelContent"> <pre>tableRows = cursor.fetchone()[0] + if tableRows is None: + tableRows = 0 </pre> </div></div> <p>If you do that you'll still have a </p> <div class="preformatted panel" style="border-width: 1px;"><div class="preformattedContent panelContent"> <pre> TypeError: 'NoneType' object has no attribute '__getitem__' </pre> </div></div> <p>because it's cursor.fetchone() which return None, I suggest this if you don't mind.</p> <div class="preformatted panel" style="border-width: 1px;"><div class="preformattedContent panelContent"> <pre>tableRows = cursor.fetchone() tableRows = tableRows[0] if tableRows is not None else 0 </pre> </div></div> <p>This sounds somehow strange to me. Since SQL is max<img class="emoticon" src="https://pfspipe.ipmu.jp/jira/images/icons/emoticons/star_yellow.png" height="16" width="16" align="absmiddle" alt="" border="0"/>, it shall return at least one row, and fetchone() shall return that value. If no, there could be another error such as connection or table definition.</p> <p><tt>MAX()</tt> will return NULL on empty tables. I think a standard fix is to use <tt>COALESCE(MAX(...), 0)</tt>, where <tt>COALESCE</tt> returns the first non-NULL value in its arguments.</p> <p>If we want to go SQL, I want to point we would better to use NULLIF...</p> <p>Yes, in fact I was wrong. <br/> COALESCE seems fine, I've just tested it. </p> <div class="preformatted panel" style="border-width: 1px;"><div class="preformattedContent panelContent"> <pre>cursor.execute("select COALESCE(MAX(%s),0) from %s" % (idLab, tableName)) tableRows = cursor.fetchone() tableRows = tableRows[0] if tableRows is not None else 0 </pre> </div></div> <p>Should we merge and close that issue ?</p> <p>I posted a wrong comment sorry. NULLIF is the opposite operation.</p> <p>For fix, if we put null validation code in SQL, I'd rather propose to arise exception (but not by print) than handling None for fetchone(), since the error shall be invoked or injected well before the SQL just executed. So, I'd propose</p> <div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent"> <pre class="code-python"> cursor.execute(<span class="code-quote">"select COALESCE(MAX(%s),0) <span class="code-keyword">from</span> %s"</span> % (idLab, tableName)) tableRows = cursor.fetchone() <span class="code-keyword">if</span> tableRows <span class="code-keyword">is</span> <span class="code-keyword"><span class="code-object">None</span></span>: <span class="code-keyword">raise</span> <span class="code-object">ValueError</span>(<span class="code-quote">'Could <span class="code-keyword">not</span> get MAX(%s) <span class="code-keyword">from</span> %s'</span> % (idLab, tableName)) <span class="code-keyword">else</span>: tableRows = tableRows[0] </pre> </div></div> <p>or similar.</p> <p>merged.</p> Development Rank 0|ii0273: Reviewers arnaud.lefur