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107 lines
3.2 KiB
107 lines
3.2 KiB
14 years ago
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'''
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DDL statements for Elixir.
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Entities having the perform_ddl statement, will automatically execute the
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given DDL statement, at the given moment: ether before or after the table
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creation in SQL.
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The 'when' argument can be either 'before-create' or 'after-create'.
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The 'statement' argument can be one of:
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- a single string statement
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- a list of string statements, in which case, each of them will be executed
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in turn.
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- a callable which should take no argument and return either a single string
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or a list of strings.
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In each string statement, you may use the special '%(fullname)s' construct,
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that will be replaced with the real table name including schema, if unknown
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to you. Also, self explained '%(table)s' and '%(schema)s' may be used here.
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You would use this extension to handle non elixir sql statemts, like triggers
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etc.
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.. sourcecode:: python
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class Movie(Entity):
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title = Field(Unicode(30), primary_key=True)
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year = Field(Integer)
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perform_ddl('after-create',
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"insert into %(fullname)s values ('Alien', 1979)")
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preload_data is a more specific statement meant to preload data in your
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entity table from a list of tuples (of fields values for each row).
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.. sourcecode:: python
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class Movie(Entity):
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title = Field(Unicode(30), primary_key=True)
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year = Field(Integer)
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preload_data(('title', 'year'),
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[(u'Alien', 1979), (u'Star Wars', 1977)])
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preload_data(('year', 'title'),
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[(1982, u'Blade Runner')])
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preload_data(data=[(u'Batman', 1966)])
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'''
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from elixir.statements import Statement
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from elixir.properties import EntityBuilder
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from sqlalchemy import DDL
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__all__ = ['perform_ddl', 'preload_data']
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__doc_all__ = []
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#
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# the perform_ddl statement
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#
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class PerformDDLEntityBuilder(EntityBuilder):
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def __init__(self, entity, when, statement, on=None, context=None):
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self.entity = entity
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self.when = when
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self.statement = statement
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self.on = on
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self.context = context
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def after_table(self):
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statement = self.statement
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if hasattr(statement, '__call__'):
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statement = statement()
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if not isinstance(statement, list):
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statement = [statement]
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for s in statement:
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ddl = DDL(s, self.on, self.context)
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ddl.execute_at(self.when, self.entity.table)
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perform_ddl = Statement(PerformDDLEntityBuilder)
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#
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# the preload_data statement
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#
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class PreloadDataEntityBuilder(EntityBuilder):
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def __init__(self, entity, columns=None, data=None):
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self.entity = entity
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self.columns = columns
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self.data = data
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def after_table(self):
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all_columns = [col.name for col in self.entity.table.columns]
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def onload(event, schema_item, connection):
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columns = self.columns
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if columns is None:
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columns = all_columns
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data = self.data
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if hasattr(data, '__call__'):
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data = data()
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insert = schema_item.insert()
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connection.execute(insert,
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[dict(zip(columns, values)) for values in data])
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self.entity.table.append_ddl_listener('after-create', onload)
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preload_data = Statement(PreloadDataEntityBuilder)
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