Why I Hate the Django ORM

Transcript

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

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

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

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

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

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6. TAKING A STEP BACK
   Thursday, January 12, 2012
   

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

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

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9. 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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10. 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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11. AGGREGATES TAKE STRINGS
    (NOT EXPRESSIONS OR
    ANYTHING ELSE USEFUL)
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12. NO COMPOSABILITY
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13. WEREN’T DESIGNED WITH
    EACH OTHER IN MIND
    MUCH LESS A
    COMPREHENSIVE SYSTEM
    Thursday, January 12, 2012
    

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

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

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

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19. SIMPLE THINGS ARE SIMPLE
    MEDIUM THINGS ARE POSSIBLE
    HARD THINGS AREN’T
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20. SIMPLE THINGS SHOULD BE SIMPLE
    HARD THINGS SHOULD BE POSSIBLE
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21. SPEAKING OF SIMPLE...
    Event.objects.filter(
    start_date__hour=10
    )
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22. AND OUGHT TO BE SIMPLE
    Event.objects.filter(
    start_date__hour__gt=11
    )
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23. __ SYNTAX IS NEAT
    BUT LIMITED
    Thursday, January 12, 2012
    

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

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

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26. 80/20 SOLUTION
    BUT IT COULD BE 90/10
    Thursday, January 12, 2012
    

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27. THANKS
    QUESTIONS?
    Thursday, January 12, 2012
    

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