DynamoDB table attributes are deleting when executing a put_item from a Lambda Python

Question

I have a situation where all attributes in a table are being deleted except for the PK and the attribute I did put against.  After Python Lambda executes a put all attributes except for the OK and attributes I did put against are elevated.

For example (all strings):
- ID //the PK
- AttrA
- AttrB
- AttrC

I perform the following put:
Resp = table.put_item(
        Item={
            'ID': '1',
            'AttrA': accta (a local Python string var)
        }
    )

Resp shows a positive return of 200, and a transaction occurred.

When I go to the DynamoDB console and look at the table, AttrB and AttrC have been deleted.

Should I be using a table.update_item instead?

Osvaldo Marte · Answer

Yes, the behavior you're seeing is expected when using put_item in DynamoDB. The put_item operation in DynamoDB creates a new item or replaces an existing item with the same primary key. This means that any attributes that are not included in the put_item request will be deleted. [1] Source

💡 If you want to update specific attributes of an existing item without affecting the other attributes, you should use the update_item operation instead. [2] source

> 💡 If you want to update specific attributes of an existing item without affecting the other attributes, you should use the `update_item` operation instead. [[2] source](https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/dynamodb/client/update_item.html#update-item)

DynamoDB table attributes are deleting when executing a put_item from a Lambda Python

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