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https://github.com/jazzband/django-ddp.git
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46 lines
1.3 KiB
Python
46 lines
1.3 KiB
Python
"""Django DDP utils for DDP messaging."""
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from copy import deepcopy
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from dddp import THREAD_LOCAL as this, REMOVED
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try:
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from django.db.models.expressions import ExpressionNode
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except AttributeError:
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ExpressionNode = None
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def obj_change_as_msg(obj, msg):
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"""Generate a DDP msg for obj with specified msg type."""
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if ExpressionNode is None:
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exps = False
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else:
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# check for F expressions
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exps = [
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name for name, val in vars(obj).items()
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if isinstance(val, ExpressionNode)
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]
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if exps:
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# clone and update obj with values but only for the expression fields
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obj = deepcopy(obj)
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# Django 1.8 makes obj._meta public --> pylint: disable=W0212
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for name, val in obj._meta.model.objects.values(*exps).get(pk=obj.pk):
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setattr(obj, name, val)
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# run serialization now that all fields are "concrete" (not F expressions)
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serializer = this.serializer
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data = serializer.serialize([obj])[0]
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# collection name is <app>.<model>
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name = data['model']
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# cast ID as string
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if not isinstance(data['pk'], basestring):
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data['pk'] = '%d' % data['pk']
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payload = {
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'msg': msg,
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'collection': name,
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'id': data['pk'],
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}
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if msg != REMOVED:
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payload['fields'] = data['fields']
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return (name, payload)
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