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Modeling: User's Guide |  |
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Before dealing with all the details, here is an overview of a PyModel. Note the the id default property for entities, as well as the predefined Attribute sub-types, APrimaryKey and AString.
from Modeling.PyModel import *
# Set preferred defaults for this model (when different from
# standard defaults, or if we want to make things explicit)
AFloat.defaults['precision'] = 10
AFloat.defaults['scale'] = 2
AString.defaults['width'] = 40
Association.defaults['delete']=['nullify', 'nullify']
Entity.defaults['properties'] = [
APrimaryKey('id', isClassProperty=0, isRequired=1, doc='PK')
]
_connDict = {'database': 'AUTHOR_BOOKS'}
model = Model('AuthorBooks',adaptorName='Postgresql', connDict=_connDict)
model.version='0.1'
model.entities = [
#
Entity('Book',
properties=[ AString('title', isRequired=1, columnName='title'),
AFloat('price'),
],
),
Entity('Writer',
properties=[ AString('lastName',isRequired=1, width=30,
displayLabel='Last Name', ),
AString('firstName', displayLabel='First Name', ),
AInteger('age', displayLabel='Age', ),
ADateTime('birthday', usedForLocking=0,
displayLabel='birthday', ),
]
),
]
model.associations=[
Association('Book', 'Writer',
relations=['author', 'books'],
delete=['nullify', 'cascade']),
Association('Writer', 'Writer',
relations=['pygmalion', None],
delete=['nullify', None]),
]
A PyModel is typically made of two parts: a first part sets the defaults, then
the second one defines the model. Defaults helps you keep the model definition
tidy, by removing the repetitive parts from the model definition itself; in
this example, the defaults add a primary key to each entity, sets the
width for strings, etc.
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Modeling: User's Guide | |
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