DynamoDB in examples, Example 4.1: Search

import datetime

from uuid import uuid4

from ddb_table import DDBTable, DDBUUIDField, DDBStrField


DDB_LOCAL_URL = 'http://localhost:8010'


class DDBTweet(DDBTable):

    TABLE_NAME = 'tweet'
    KEY_SCHEMA = [{
        'AttributeName': 'tweet_id',
        'KeyType': 'HASH',
    }]
    PROVISIONED_THROUGHPUT = {
        'ReadCapacityUnits': 1,
        'WriteCapacityUnits': 1
    }
    GLOBAL_SECONDARY_INDEXES = [{
        'IndexName': 'by_text',
        'KeySchema': [{
                'AttributeName': 'upper_first',
                'KeyType': 'HASH'
            }, {
                'AttributeName': 'upper_rest',
                'KeyType': 'RANGE'
            }
        ],
        'Projection': {
            'ProjectionType': 'ALL',
        },
        'ProvisionedThroughput': {
            'ReadCapacityUnits': 1,
            'WriteCapacityUnits': 1,
        }
    }]
    FIELDS = {
        'tweet_id': DDBUUIDField,
        'text': DDBStrField,
        'created': DDBStrField,
        'upper_first': DDBStrField,
        'upper_rest': DDBStrField,
    }

    def _get_endpoint_url(self):
        return DDB_LOCAL_URL

    def create(self, text):
        tweet_id = uuid4()
        created = str(datetime.datetime.utcnow())
        upper = text.upper()
        data = {
            'tweet_id': tweet_id,
            'text': text,
            'created': created,
            'upper_first': upper[:2],
            'upper_rest': upper[2:],
        }
        response = self._dynamodb(operation='PutItem').call(
            TableName=self._get_table_name(),
            Item=self.encode_item(data=data))
        return data

    def search(self, text, last=None, limit=10):
        if not text:
            return ([], None)
        upper = text.upper()
        ddb_query = self._dynamodb(operation='Query')
        kwargs = {
            'TableName': self._get_table_name(),
            'IndexName': 'by_text',
        }
        if len(text) > 1:
            kwargs.update({
                'KeyConditions': {
                    'upper_first': {
                        'AttributeValueList': [{
                            'S': upper[:2],
                        }],
                        'ComparisonOperator': 'EQ'
                    },
                    'upper_rest': {
                        'AttributeValueList': [{
                            'S': upper[2:],
                        }],
                        'ComparisonOperator': 'BEGINS_WITH'
                    }
                }
            })
        else:
            kwargs.update({
                'KeyConditions': {
                    'upper_first': {
                        'AttributeValueList': [{
                            'S': upper[:2],
                        }],
                        'ComparisonOperator': 'EQ'
                    },
                }
            })
        if last:
            kwargs['ExclusiveStartKey'] = last
        result = ddb_query.call(**kwargs)
        return (
            [self.decode_item(item) for item in result.get('Items')],
            result.get('LastEvaluatedKey'))


if __name__ == '__main__':
    ddb_tweet = DDBTweet()
    ddb_tweet.create_table()
    for text in ['text1', 'text2', 'text3', 'Text4', 'Another text']:
        ddb_tweet.create(text=text)
    print(ddb_tweet.search(text='t'))
    print(ddb_tweet.search(text='text4'))
    print(ddb_tweet.search(text='not found'))

    # ([{'upper_first': 'TE', 'upper_rest': 'XT1', 'tweet_id': '5aac3887-3da4-41c3-b158-4d9624248e46', 'text': 'text1', 'created': '2015-05-30 13:43:01.174688'}, {'upper_first': 'TE', 'upper_rest': 'XT2', 'tweet_id': '95b8330a-0d56-41b8-9389-a8ae4fd27d70', 'text': 'text2', 'created': '2015-05-30 13:43:01.265926'}, {'upper_first': 'TE', 'upper_rest': 'XT3', 'tweet_id': 'd079d36b-e902-4f0e-91de-03b285756d27', 'text': 'text3', 'created': '2015-05-30 13:43:01.290698'}, {'upper_first': 'TE', 'upper_rest': 'XT4', 'tweet_id': '67e6c96b-f828-42dc-89b9-770f309e920e', 'text': 'Text4', 'created': '2015-05-30 13:43:01.314380'}], None)
    # ([{'upper_first': 'TE', 'upper_rest': 'XT4', 'tweet_id': '67e6c96b-f828-42dc-89b9-770f309e920e', 'text': 'Text4', 'created': '2015-05-30 13:43:01.314380'}], None)
    # ([], None)