Amazon DynamoDB Scan With Pagination

arazzo: 1.0.1
info:
  title: Amazon DynamoDB Scan With Pagination
  summary: Scan a table and page through results until the table is exhausted.
  description: >-
    Reads every matching item from a table by issuing an initial Scan and
    then repeatedly continuing the scan from the returned LastEvaluatedKey
    until DynamoDB stops returning one, signalling the end of the table.
    This is the canonical full-table-scan pagination loop. Every step
    spells out its request inline, including the AWS JSON protocol
    X-Amz-Target header, so the flow can be read and executed without
    opening the underlying OpenAPI description.
  version: 1.0.0
sourceDescriptions:
- name: dynamodbApi
  url: ../openapi/amazon-dynamodb-openapi.yml
  type: openapi
workflows:
- workflowId: scan-paginate
  summary: Scan a table and follow LastEvaluatedKey until the scan is complete.
  description: >-
    Runs an initial Scan, then branches: while a LastEvaluatedKey is
    returned it continues the scan from that key, and when none is returned
    it ends.
  inputs:
    type: object
    required:
    - tableName
    properties:
      tableName:
        type: string
        description: The name of the table to scan.
      filterExpression:
        type: string
        description: Optional filter expression to apply to scanned items.
      expressionAttributeNames:
        type: object
        description: Optional substitution tokens for attribute names.
      expressionAttributeValues:
        type: object
        description: Optional values substituted into the filter expression.
      limit:
        type: integer
        description: Maximum number of items to evaluate per page.
  steps:
  - stepId: scanFirstPage
    description: Run the initial scan over the table.
    operationId: scan
    parameters:
    - name: X-Amz-Target
      in: header
      value: DynamoDB_20120810.Scan
    requestBody:
      contentType: application/x-amz-json-1.0
      payload:
        TableName: $inputs.tableName
        FilterExpression: $inputs.filterExpression
        ExpressionAttributeNames: $inputs.expressionAttributeNames
        ExpressionAttributeValues: $inputs.expressionAttributeValues
        Limit: $inputs.limit
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      items: $response.body#/Items
      lastEvaluatedKey: $response.body#/LastEvaluatedKey
    onSuccess:
    - name: morePages
      type: goto
      stepId: scanNextPage
      criteria:
      - context: $response.body
        condition: $.LastEvaluatedKey != null
        type: jsonpath
    - name: scanComplete
      type: end
      criteria:
      - context: $response.body
        condition: $.LastEvaluatedKey == null
        type: jsonpath
  - stepId: scanNextPage
    description: >-
      Continue the scan from the previous page's LastEvaluatedKey, looping
      until DynamoDB returns no further LastEvaluatedKey.
    operationId: scan
    parameters:
    - name: X-Amz-Target
      in: header
      value: DynamoDB_20120810.Scan
    requestBody:
      contentType: application/x-amz-json-1.0
      payload:
        TableName: $inputs.tableName
        FilterExpression: $inputs.filterExpression
        ExpressionAttributeNames: $inputs.expressionAttributeNames
        ExpressionAttributeValues: $inputs.expressionAttributeValues
        Limit: $inputs.limit
        ExclusiveStartKey: $steps.scanFirstPage.outputs.lastEvaluatedKey
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      items: $response.body#/Items
      lastEvaluatedKey: $response.body#/LastEvaluatedKey
    onSuccess:
    - name: stillMorePages
      type: goto
      stepId: scanNextPage
      criteria:
      - context: $response.body
        condition: $.LastEvaluatedKey != null
        type: jsonpath
    - name: done
      type: end
      criteria:
      - context: $response.body
        condition: $.LastEvaluatedKey == null
        type: jsonpath
  outputs:
    lastPageItems: $steps.scanNextPage.outputs.items