I am deleting a non-existing record from the dynamodb table using dynamoDbMapper.delete(object) which uses default DynamoDBDeleteExpression
I was expecting some sort of exception to arise since the record is absent from the DB but it does nothing. It does not even have a return type which could tell if the delete was successful or failure. Is there a way to add a delete expression or something which will make my delete throw an exception if the item is absent from the db?
It is by design:
Unless you specify conditions, the DeleteItem is an idempotent operation; running it multiple times on the same item or attribute does not result in an error response.
FROM: https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_DeleteItem.html
It's possible to utilize ReturnValues to determine if delete did anything or not. If ReturnValues.Attributes is empty, it means delete didn't find a record to delete, and you can throw an error in this case. Example in JavaScript:
async function deleteWithThrowIfNotExists() {
const dynamo = new AWS.DynamoDB.DocumentClient();
const parameters = {
Key: {
user: 'john'
},
ReturnValues: 'ALL_OLD',
TableName: 'users'
};
const response = await dynamo.delete(parameters).promise();
if (!response.Attributes) {
throw new Error('Cannot delete item that does not exist')
}
}
You can first load the item, and if item doesn't exists you can throw exception otherwise delete it.