mirror of https://github.com/kivy/kivy.git
73 lines
2.6 KiB
Python
73 lines
2.6 KiB
Python
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# ----------------------------------------------------------------------------
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#
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# Simulate a datastore for an app.
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#
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# In a system of models for this sample fruit data, we would have two record
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# types, category and fruit, with category having a to_many relationship to
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# fruit and with fruit having a to_one relationship to category.
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#
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# In ListAdapter and the system or related classes, we sync selection in the
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# user interface to selection of datastore, datarecord properties. In the
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# datastore treatment here, we use dictionaries for the data, but we could just
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# as well define the attributes of the following DataModel stubs and used
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# instances of them in a simulated database:
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#
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# class DataModel(object):
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# pass
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#
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#
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# class FruitCategoryRecord(DataModel):
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# pass
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#
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#
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# class FruitRecord(DataModel):
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# pass
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#
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#
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# The DataStore below does not use such classes as FruitCategoryRecord and
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# FruitRecord. It uses dictionaries.
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from kivy.properties import StringProperty, DictProperty
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class DataStore(object):
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def __init__(self, name, db_dict):
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self.name = name
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self.db_dict = db_dict
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def set(self, key, prop, val):
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if key in self.db_dict:
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if prop in self.db_dict[key]:
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self.db_dict[key][prop] = val
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return
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msg = "DataStore {0} set: no property {1} in record[{2}]".format(
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self.name, prop, key)
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raise Exception(msg)
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msg = "DataStore {0} set: unknown record for key: {1}".format(
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self.name, key)
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raise Exception(msg)
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def get(self, key, prop):
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if key in self.db_dict:
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if prop in self.db_dict[key]:
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return self.db_dict[key][prop]
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msg = "DataStore {0} get: no property {1} in record[{2}]".format(
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self.name, prop, key)
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raise Exception(msg)
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msg = "DataStore {0} get: unknown record for key: {1}".format(
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self.name, key)
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raise Exception(msg)
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return None
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# NOTE: When creating a datastore system for your app, you could create classes
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# like the ones stubbed out above, intead of relying on dictionaries. You
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# could also put the raw data in JSON, and create an interface. However
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# it is done, to work with the ListAdapter and selection system, the
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# data models need to include is_selected somehow.
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#
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# In fruits example data, all fruit category keys and fruit keys are
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# unique, so they work as record ids. However, for your work, you may
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# wish to have record ids as keys.
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