Dynamodb on The Edge Cases

DynamoDB Can Take a Static Table Name

Fri, 19 Jan 2024 19:09:51 +0000

CDK autogenerates resource names for every resource in your stack. However some, like DynamoDB, can take a table_name argument, making it a statically named resource. There are a lot of use cases this can benefit, one I’ve used it for was for a table that needed to be accessed by both dev and prod environments, and so needed to be recreated (using from_table_attributes instead of from_table_name so that we have access to any streams) for non-prod environments for access.

Creating a Model Instance with from_raw_data() in PynamoDB

Thu, 26 Jan 2023 19:16:08 +0000

When using from_raw_data in PynamoDB, you have to pass in the DynamoDB dict structure ({"attribute_name": {"S": "value"}), not a plain dictionary. When 6.0.0 comes out, there will be to_dict and from_dict methods.

Until to_dict and from_dict are released, use this to convert a Pynamo object to a dictionary: found_record_dict = found_record.__dict__.get("attribute_values", found_record.__dict__)

Proejct Source

DynamoDB Index Read and Write Capacity in PynamoDB

Fri, 04 Feb 2022 19:42:30 +0000

When setting up a Global Secondary Index model in PynamoDB, the read and write capacity units have to be specified. These are not needed if not provisioning a table or index, yet are not optional. Arbitrary values can be used and nothing will be done with them.

Example

class ModelIndex(GlobalSecondaryIndex):
  class Meta:
      index_name = "model-index"
      read_capacity_index = 0  # Not used, since the table isn't being provisioned
      write_capacity_index = 0
      projection = AllProjection
  model_key = UnicodeAttribute(hash_key=True)

PynamoDB Field Aliases

Fri, 04 Feb 2022 17:59:50 +0000

To give an alias to DynamoDB field with PynamoDB, use the attr_name parameter for the appropriate attribute constructor:

class Thread(Model):
class Meta:
    table_name = 'Thread'
forum_name = UnicodeAttribute(hash_key=True)
# This attribute will be called 'tn' in DynamoDB
thread_name = UnicodeAttribute(null=True, attr_name='tn')

PynamoDB Arguments

Wed, 26 Jan 2022 04:37:46 +0000

In PynamoDB, when running a DynamoDB query, the first two positional arguments are the hash key (primary key) and filters for the range key (sort key). To do a filter expression without querying on the range key, explicitly provide the filter_condition_expression parameter.

Example

    return [
        post
        for post in PostModel.query(
            user_id,
            filter_condition=(PostModel.media_type == "IMAGE") & PostModel.image_key.exists(),
            limit=100,
        )
    ]
    ```