Why I Hate the Django ORM

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WHY I HATE THE DJANGO ORM Thursday, January 12, 2012

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HI, I’M ALEX I HATE THE DJANGO ORM Thursday, January 12, 2012

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I ALSO HELP BUILD IT (SO ALL OF THIS STUFF IS REALLY MY FAULT) Thursday, January 12, 2012

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WHY DO I HATE IT? Thursday, January 12, 2012

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SELECT event_type SUM(end_time - start_time) FROM event GROUP BY event_type Thursday, January 12, 2012

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TAKING A STEP BACK Thursday, January 12, 2012

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WHY DO WE HAVE AN ORM? DATABASE RECORDS INTO OBJECTS EXECUTE COMMON QUERIES NOT REPLACE SQL Thursday, January 12, 2012

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WAS THAT A COMMON QUERY? Thursday, January 12, 2012

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IT HAS A SYNTAX Event.objects.values( “event_type” ).annotate( Sum(F(“end_time”) - F(“start_time”)) ) Thursday, January 12, 2012

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Traceback (most recent call last): File "", line 1, in File ".../query.py", line 741, in annotate is_summary=False) File ".../sql/query.py", line 990, in add_aggregate field_list = aggregate.lookup.split(LOOKUP_SEP) AttributeError: 'ExpressionNode' object has no attribute 'split' FFFFFFFUUUUUUUUUUUU Thursday, January 12, 2012

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AGGREGATES TAKE STRINGS (NOT EXPRESSIONS OR ANYTHING ELSE USEFUL) Thursday, January 12, 2012

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NO COMPOSABILITY Thursday, January 12, 2012

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WEREN’T DESIGNED WITH EACH OTHER IN MIND MUCH LESS A COMPREHENSIVE SYSTEM Thursday, January 12, 2012

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SQLALCHEMY session.query( TimlineEvent.event_type, func.sum(TimelineEvent.end_time - TimelineEvent.start_time) ).group_by( TimelineEvent.event_type ).all() Thursday, January 12, 2012

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NOTICE THAT? SQLALCHEMY USES THE SAME SYNTAX FOR FIELDS, EVERYWHERE Thursday, January 12, 2012

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DJANGO DOESN’T F(“field_name”) Aggregate(“field_name”) Q(field_name=value) filter(field_name=value) Thursday, January 12, 2012

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STRINGS, KEYWORD ARGUMENTS, AND FUNKY ONE-LETTER OBJECTS (WITH VARYING LEVELS OF INTEROPERABILITY) Thursday, January 12, 2012

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WHEN DO YOU USE WHICH? I HAVE NO IDEA (AND I WROTE THE DAMNED THING) Thursday, January 12, 2012

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SIMPLE THINGS ARE SIMPLE MEDIUM THINGS ARE POSSIBLE HARD THINGS AREN’T Thursday, January 12, 2012

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SIMPLE THINGS SHOULD BE SIMPLE HARD THINGS SHOULD BE POSSIBLE Thursday, January 12, 2012

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SPEAKING OF SIMPLE... Event.objects.filter( start_date__hour=10 ) Thursday, January 12, 2012

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AND OUGHT TO BE SIMPLE Event.objects.filter( start_date__hour__gt=11 ) Thursday, January 12, 2012

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__ SYNTAX IS NEAT BUT LIMITED Thursday, January 12, 2012

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THE IDEALS OF THE ORM ARE GOOD THE API IS GREAT FOR SIMPLE CASES Thursday, January 12, 2012

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BUT THE INCONSISTENCIES BLEED AND THINGS THAT SHOULD BE EASY AREN’T Thursday, January 12, 2012