ch11-24: clean up by @eumiro & sync with Atlas

23-dyn-attr-prop/oscon/schedule_v2.py

@@ -0,0 +1,76 @@
+"""
+schedule_v2.py: property to get venue linked to an event
+
+# tag::SCHEDULE2_DEMO[]
+    >>> event = Record.fetch('event.33950')  # <1>
+    >>> event  # <2>
+    <Event 'There *Will* Be Bugs'>
+    >>> event.venue  # <3>
+    <Record serial=1449>
+    >>> event.venue.name  # <4>
+    'Portland 251'
+    >>> event.venue_serial  # <5>
+    1449
+
+# end::SCHEDULE2_DEMO[]
+"""
+
+# tag::SCHEDULE2_RECORD[]
+import json
+import inspect  # <1>
+
+JSON_PATH = 'data/osconfeed.json'
+
+class Record:
+
+    __index = None  # <2>
+
+    def __init__(self, **kwargs):
+        self.__dict__.update(kwargs)
+
+    def __repr__(self):
+        cls_name = self.__class__.__name__
+        return f'<{cls_name} serial={self.serial!r}>'
+
+    @staticmethod  # <3>
+    def fetch(key):
+        if Record.__index is None:  # <4>
+            Record.__index = load()
+        return Record.__index[key]  # <5>
+# end::SCHEDULE2_RECORD[]
+
+
+# tag::SCHEDULE2_EVENT[]
+class Event(Record):  # <1>
+
+    def __repr__(self):
+        if hasattr(self, 'name'):  # <2>
+            cls_name = self.__class__.__name__
+            return f'<{cls_name} {self.name!r}>'
+        else:
+            return super().__repr__()
+
+    @property
+    def venue(self):
+        key = f'venue.{self.venue_serial}'
+        return self.__class__.fetch(key)  # <3>
+# end::SCHEDULE2_EVENT[]
+
+# tag::SCHEDULE2_LOAD[]
+def load(path=JSON_PATH):
+    records = {}
+    with open(path) as fp:
+        raw_data = json.load(fp)
+    for collection, raw_records in raw_data['Schedule'].items():
+        record_type = collection[:-1]  # <1>
+        cls_name = record_type.capitalize()  # <2>
+        cls = globals().get(cls_name, Record)  # <3>
+        if inspect.isclass(cls) and issubclass(cls, Record):  # <4>
+            factory = cls  # <5>
+        else:
+            factory = Record  # <6>
+        for raw_record in raw_records:  # <7>
+            key = f'{record_type}.{raw_record["serial"]}'
+            records[key] = factory(**raw_record)  # <8>
+    return records
+# end::SCHEDULE2_LOAD[]