Revision d79d8208 README.develop

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  You can now apply this migration with: ./manage.py migrate db


  		





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    bkarak@nefarian:~/devel/synnefo$ ./manage.py migrate db


  		





  
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    $ ./manage.py migrate db


  		





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     Running migrations for db:


  		





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     - Migrating forwards to 0002_auto__add_field_synnefouser_new_south_test_field.


  		





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     > db:0002_auto__add_field_synnefouser_new_south_test_field


  		





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South needs some extra definitions to the model to preserve and migrate the existing data, for example, if we add a field


  		





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in a model, we should declare its default value. If not, South will propably fail, after indicating the error.


  		





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[don't understand the above, Example?]


  		





  
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    $ ./bin/python manage.py schemamigration db --auto


  		





  
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     ? The field 'SynnefoUser.new_south_field_2' does not have a default specified, yet is NOT NULL.


  		





  
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     ? Since you are adding or removing this field, you MUST specify a default


  		





  
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     ? value to use for existing rows. Would you like to:


  		





  
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     ?  1. Quit now, and add a default to the field in models.py


  		





  
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     ?  2. Specify a one-off value to use for existing columns now


  		





  
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     ? Please select a choice: 1


  		





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*Data migrations:


  		





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    For database operations (column additions, alter tables etc) we use the South database API


  		





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    (http://south.aeracode.org/docs/databaseapi.html).


  		





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    To access the data, we use the database reference (orm) provided as parameter in forwards, backwards declarations. <--What does this mean?


  		





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    For example:


  		





  
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    To access the data, we use the database reference (orm) provided as parameter in forwards, backwards method declarations


  		





  
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    in the migration script. For example:


  		





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    class Migration(DataMigration):


  		





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