Retrieve attachments and attachment metadata

  • Release version: Yokohama
  • Updated January 30, 2025
  • 2 minutes to read
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    Summary of Retrieve attachments and attachment metadata

    TheNowAttachmentService APIallows ServiceNow customers to manage attachments within their ServiceNow instance. It supports creating, reading, updating, and deleting (CRUD) attachments, as well as retrieving associated metadata. This API is essential for integrating attachment handling directly into custom applications or workflows, providing a programmatic way to upload, download, delete, validate, and query attachment metadata tied to specific records.

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    Key Features

    • Attachment Upload: Upload attachments and associate them with specific ServiceNow records.
    • Attachment Download: Download one or multiple attachments efficiently.
    • Attachment Deletion: Remove attachments as needed.
    • Attachment Validation: Validate attachments by comparing computed and expected hashes to ensure data integrity.
    • Metadata Retrieval: Retrieve metadata generated by ServiceNow when attachments are uploaded.
    • Multiple Result Handling Methods: API methods support three ways to return results: completion handlers, async/await calls, and (deprecated) Combine publishers, giving flexibility for integration with different Swift concurrency models.
    • Pagination for Metadata: When retrieving metadata for multiple attachments, use the attachmentMetadataPaginator method to handle large data sets via a Paginator object. This supports infinite scroll or paged data views in UI components like UITableView, UICollectionView, or SwiftUI List.
    • Paginator API: The Paginator object provides methods like first(), last(), next(), previous(), and reset() to navigate pages of metadata. Some methods may throw exceptions when no more pages exist. It also exposes properties to gain insights into pagination state.

    Practical Use for ServiceNow Customers

    To leverage this API, customers must import the NowData framework and initialize a NowAttachmentService object pointing to their ServiceNow instance URL. This setup enables seamless integration of attachment operations into mobile or custom apps.

    Using the paginator for metadata retrieval is particularly useful for interfaces displaying large numbers of attachments, ensuring smooth user experiences with incremental data loading and efficient memory usage.

    Overall, the NowAttachmentService API empowers customers to automate and enhance attachment management within their ServiceNow environments, improving data handling and user interactions related to attachments.

    The NowAttachmentService API enables you to perform CRUD operations on attachments and retrieve attachment metadata from your ServiceNow instance.

    Using this API you can:
    • Upload attachments to your ServiceNow instance and associated them to a specific record.
    • Download one or more attachments.
    • Delete attachments.
    • Validate an attachment by comparing the computed hash of the attachment to the expected hash.
    • Download attachment metadata. This metadata is generated by your ServiceNow instance when an attachment is uploaded.

    For additional information on working with attachments, see Attachment API.

    All NowAttachmentService methods provide three implementations for returning results data. One that calls a completion handler with the return results, one that preforms an async/await, and another that returns a Combine publisher (deprecated). For example, each upload() method uploads and associates a specified attachment to a specified record. However, the NowAttachmentService - upload(data: Data, configuration: NowAttachmentUploadConfiguration, progressUpdate: @escaping ProgressUpdate, completion: @escaping (Result<NowAttachmentMetadata, NowDataError>)) method calls a completion handler with the return results, the NowAttachmentService - upload(data: Data, configuration: NowAttachmentUploadConfiguration, progressUpdate: @escaping ProgressUpdate) async throws method performs an async/await, and the NowAttachmentService - upload(data: Data, configuration: NowAttachmentUploadConfiguration, progressUpdate: @escaping ProgressUpdate) method returns a Combine publisher.

    Before you are able to use the NowAttachmentService API, you must import NowData and then initialize a NowAttachmentService object.
    // Import the NowData framework
import NowData

func makeAttachmentService(instanceUrl: URL, 
  completion: @escaping ((Result<NowAttachmentService, NowServiceErrors>) → Void))

    Attachment metadata pagination

    You can use the NowAttachmentService methods to download attachment metadata for one or more attachments. When downloading metadata from multiple attachments, you may want to use the NowAttachmentService - attachmentMetadataPaginator(filter: Filter, limit: Int) method, which returns a Paginator object that enables you to easily iterate over the potentially large amount of data that is returned. You typically use paginated return results to provide infinite scroll capabilities for data presented inside a UITableView, a UICollectionView (UIKit), or a List (SwiftUI), or to simplify page iteration of results in general.

    After obtaining a Paginator object, subscribe to its publisher to start receiving data.
    paginator.publisher
  .subscribe(on: DispatchQueue.global())
  .receive(on: DispatchQueue.main)
  .sink { ... }
  .store(in: &subscriptions)
    The returned Paginator object provides the following methods that enable you to page through the returned records:
    • first()
    • last()
    • next()
    • previous()
    • reset()
    Note:
    Some Paginator methods may throw an exception, such as when there are no more pages to fetch.

    In addition, the Paginator object provides properties that enable you to obtain insights into the paginated data. For additional details on these properties and the available methods, see Paginator API - iOS.