Question: How do you handle empty strings in DynamoDB?

Answer

Store an empty string directly in a non-key DynamoDB attribute; no service setting is required. Empty String and Binary values are allowed outside key attributes, including inside maps and lists.

A JavaScript v3 document-client item can contain nickname: "". By default, that value remains a String. Setting marshallOptions.convertEmptyValues: true converts supported empty values to NULL instead, so use that option only if null is the representation your application intends.

These cases are different:

• "" is a present String with zero length.
• null is a present NULL attribute.
• An omitted attribute is absent.
• An empty set is invalid, while an empty list or map is valid.

Table and index key values cannot be empty strings or empty binary values. For a sparse GSI, omit an index-key attribute when the item should not be indexed; do not write an empty string as a substitute.

Check the stored type when migrating old code that used automatic empty-value conversion. Changing the client configuration can change filters and conditions even if the application still displays the field as blank. See data types and NULL behavior.

Source: AWS empty-value support.