DynamoDB Full Scan

_Helper functions for doing full paginated scan operations as a Promise or AsyncGenerator with the "asw-sdk" DynamoDB DocumentClient._

The DynamoDB DocumentClient class in the "aws-sdk" node package exposes Promise interfaces for its various operations via the additional .promise() method, e.g.,

``
docClient.put(params).promise();
`

You can use this Promise API with the scan operation, but if you want to do a full scan of the database, then it requires a little extra work, with most examples showing an onScan function that recursively calls itself until LastEvaluatedKey === undefined.

This library exposes two helper functions to let you get the results of a full paginated scan operation as a single Promise or lazily evaluated as an AsyncGenerator, returning the combined Items of each paginated call.

_Say goodbye to that old-fashioned and clunky onScan pattern and embrace async generators!_

fullScanSeq - async generator for all items from a full scan

Return an async generator that yields items from a full scan operation (albeit the scans are performed in a lazy manner, only being requested if you iterate up to the next page of items). You can also cast the results via the generic.

Signature:

`typescript
function* fullScanSeq(
docClient: DocumentClient,
params: DocumentClient.ScanInput
): AsyncGenerator;
`

Example:

`typescript
type Item = { id: string; name: string; description?: string };

const itemSeq = fullScanSeq(docClient, {
TableName: "items",
FilterExpression: "attribute_not_exists(#d)",
ExpressionAttributeNames: { "#d": "description" }
});

for await (let item of items) {
console.log(item: id=${item.id}, name=${item.name});
}
`

fullScanProm - single promise of all items for a full scan

Return a Promise of all the Items from a scan in a single array. Set maxDepth to limit how many times it pages and/or sleepWait to add a delay between pagination calls (in milliseconds).

Signature:

`typescript
function fullScanProm(
docClient: DocumentClient,
params: DocumentClient.ScanInput,
maxDepth = -1,
sleepWait = 0
): Promise;
`

Example:

`typescript
type Item = { id: string; name: string; description?: string };

const items = await fullScanProm(docClient, {
TableName: "items",
FilterExpression: "attribute_not_exists(#d)",
ExpressionAttributeNames: { "#d": "description" }
});

for (let item of items) {
console.log(item: id=${item.id}, name=${item.name});
}
``