Update operations treat empty string as null

[cdurante]

DynamoDB has supported empty values since 2020

https://aws.amazon.com/about-aws/whats-new/2020/05/amazon-dynamodb-now-supports-empty-values-for-non-key-string-and-binary-attributes-in-dynamodb-tables/

However, when creating an update transaction. DDB toolbox treats an update of a string field to empty as equivalent to removing it. If this attribute happens to be required an error is thrown.

See src/classes/Entity/Entity.ts

 else if (
        this._table!._removeNulls === true &&
        (data[field] === null || String(data[field]).trim() === '') &&
        !Array.isArray(data[field]) &&
        (!mapping.link || mapping.save)
      ) {
        // Verify attribute is not required
        if (schema.attributes[field].required) error(`'${field}' is required and cannot be removed`)
        REMOVE.push(`#${field}`)
        names[`#${field}`] = field
      }

It is OK for a required field to contain empty string as long as it is not PK/SK