get_multiple_fields

Retrieve multiple fields in one operation, from a single record selected by its primary key.

retrieved_items: Dict[str, Any] = table_client.get_multiple_fields(
    key_value=str, 
    getters={
        str: FieldGetter(field_path=str, query_kwargs=Optional[dict]),
        str: FieldGetter(field_path=str, query_kwargs=Optional[dict])
    },
    data_validation=bool = True
)

You can use any key for the getters

No matter the field you are trying to retrieve, you can use any key's for your getter item's. You will receive your results in a dictionary that use the keys of your getters, even if they are not related to the field names you requested.

Parameters#

Property name	Required	Accepted types	Default	Description
key_value	YES	Any	-	The path expression to target the attribute to set/update in your record. See Field path selectors
getters	YES	Dict[str, FieldGetter]	-	A dictionary with all the fields to retrieve, and the keys that will be used for the output you will receive.
data_validation	NO	bool	True	Whether data validation from your table model should be applied on the retrieved data.

Availability#

Table	Available
DynamoDBBasicTable	✅
DynamoDBCachingTable	✅
ExternalDynamoDBApiBasicTable	✅
ExternalDynamoDBApiCachingTable	✅

Queried record#

{
  "userId": "x42",
  "username": "Robinson",
  "tokens": {
    "t32": {
      "expirationTimestamp": "1618322249"
    }
  },
  "lastConnectionTimestamp": "1607220132"
}

Code#

from StructNoSQL import TableDataModel, DynamoDBBasicTable, PrimaryIndex, BaseField, MapModel, FieldGetter
from typing import Dict, Optional


class UsersTableModel(TableDataModel):
    userId = BaseField(field_type=str, required=True)
    username = BaseField(field_type=str, required=False)
    class AuthTokenModel(MapModel):
        expirationTimestamp = BaseField(field_type=int, required=True)
    tokens = BaseField(field_type=Dict[str, AuthTokenModel], key_name='tokenId', required=False)
    lastConnectionTimestamp = BaseField(field_type=int, required=False)


class UsersTable(DynamoDBBasicTable):
    def __init__(self):
        primary_index = PrimaryIndex(hash_key_name='userId', hash_key_variable_python_type=str)
        super().__init__(
            table_name='accounts-data', region_name='eu-west-2',
            data_model=UsersTableModel, primary_index=primary_index,
            auto_create_table=True
        )


table_client = UsersTable()

response_data: Optional[dict] = table_client.get_multiple_fields(
    key_value='x42', getters={
        'name': FieldGetter(field_path='username'),
        'tokenExpiration': FieldGetter(
            field_path='tokens.{{tokenId}}.expirationTimestamp',
            query_kwargs={'tokenId': 't42'}
        ),
        'lastConnectionTimestamp': FieldGetter(field_path='lastConnectionTimestamp'),
    }
)
print(response_data)

Output#

{'name': 'Robinson', 'tokenExpiration': '1618322249', 'score': 1607220132}