from functools import reduce
from boto3.dynamodb.conditions import Attr
IMAGE_TYPE = 'image'
VIDEO_TYPE = 'video'
class MediaDB(object):
def list_media_files(self, label=None):
pass
def add_media_file(self, name, media_type, labels=None):
pass
def get_media_file(self, name):
pass
def delete_media_file(self, name):
pass
class DynamoMediaDB(MediaDB):
def __init__(self, table_resource):
self._table = table_resource
def list_media_files(self, startswith=None, media_type=None, label=None):
scan_params = {}
filter_expression = None
if startswith is not None:
filter_expression = self._add_to_filter_expression(
filter_expression, Attr('name').begins_with(startswith)
)
if media_type is not None:
filter_expression = self._add_to_filter_expression(
filter_expression, Attr('type').eq(media_type)
)
if label is not None:
filter_expression = self._add_to_filter_expression(
filter_expression, Attr('labels').contains(label)
)
if filter_expression:
scan_params['FilterExpression'] = filter_expression
response = self._table.scan(**scan_params)
return response['Items']
def add_media_file(self, name, media_type, labels=None):
if labels is None:
labels = []
self._table.put_item(
Item={
'name': name,
'type': media_type,
'labels': labels,
}
)
def get_media_file(self, name):
response = self._table.get_item(
Key={
'name': name,
},
)
return response.get('Item')
def delete_media_file(self, name):
self._table.delete_item(
Key={
'name': name,
}
)
def _add_to_filter_expression(self, expression, condition):
if expression is None:
return condition
return expression & condition
