AttachmentInteractor — File and Media Attachment API

AttachmentInteractor provides all operations for browsing, loading, and managing message attachments within a channel. It is accessible via SceytChatUIKit.chatUIFacade.attachmentInteractor. Use it to implement media galleries, file browsers, voice-message lists, and link-preview feeds — each filtered by attachment type. Paginated methods return a Flow<PaginationResponse<AttachmentWithUserData>>, which emits locally cached results first and then updates from the server. Utility methods handle file checksum deduplication, link preview fetching, and transfer-state tracking. Package: com.sceyt.chatuikit.persistence.interactor

val interactor: AttachmentInteractor = SceytChatUIKit.chatUIFacade.attachmentInteractor

Paginating Attachments

getPrevAttachments

suspend fun → Flow<PaginationResponse<AttachmentWithUserData>>

Loads attachments older than lastAttachmentId (backward pagination). Each emission contains an AttachmentWithUserData list, pairing the attachment with its sender’s profile data.

interactor.getPrevAttachments(
    conversationId   = channelId,
    lastAttachmentId = oldestLoadedAttachmentId,
    types            = listOf("image", "video"),
    offset           = 0,
    ignoreDb         = false,
    loadKeyData      = LoadKeyData()
).collect { response ->
    when (response) {
        is PaginationResponse.DBResponse     -> renderFromCache(response.data)
        is PaginationResponse.ServerResponse -> renderFromServer(response.data)
        else -> {}
    }
}

Show Parameters

conversationId

Long

required

The channel ID whose attachment history is being browsed.

lastAttachmentId

Long

required

The server-assigned ID of the oldest attachment currently visible. Older items are fetched relative to this.

types

List<String>

required

Attachment type filter. Common values: "image", "video", "file", "voice", "link". Pass multiple types to load a mixed gallery.

offset

Int

required

Zero-based count of attachments already loaded in this direction.

ignoreDb

Boolean

When true, bypasses the local cache and fetches directly from the server. Default: false.

loadKeyData

LoadKeyData

Deduplication and correlation key for the request. Default: LoadKeyData().

getNextAttachments

suspend fun → Flow<PaginationResponse<AttachmentWithUserData>>

Loads attachments newer than lastAttachmentId (forward pagination). Use this when implementing a media viewer that allows navigating towards more recent files.

interactor.getNextAttachments(
    conversationId   = channelId,
    lastAttachmentId = newestLoadedAttachmentId,
    types            = listOf("file"),
    offset           = 0
).collect { response -> /* handle */ }

Show Parameters

conversationId

Long

required

The channel ID being browsed.

lastAttachmentId

Long

required

The server-assigned ID of the newest attachment currently visible.

types

List<String>

required

Attachment type filter (e.g. "image", "video", "file", "voice").

offset

Int

required

Zero-based count of attachments already loaded in this direction.

ignoreDb

Boolean

When true, skips the local cache. Default: false.

loadKeyData

LoadKeyData

Request deduplication key. Default: LoadKeyData().

getNearAttachments

suspend fun → Flow<PaginationResponse<AttachmentWithUserData>>

Loads attachments surrounding a specific attachmentId. Useful for opening a media viewer at a particular item and needing context items on both sides for swipe navigation.

interactor.getNearAttachments(
    conversationId = channelId,
    attachmentId   = focusedAttachmentId,
    types          = listOf("image", "video"),
    offset         = 0
).collect { response -> /* render viewer context */ }

Show Parameters

conversationId

Long

required

The channel ID being browsed.

attachmentId

Long

required

The server-assigned ID of the anchor attachment.

types

List<String>

required

Attachment type filter.

offset

Int

required

Zero-based pagination offset.

ignoreDb

Boolean

When true, skips the local cache. Default: false.

loadKeyData

LoadKeyData

Request deduplication key. Default: LoadKeyData().

Updating Attachment Metadata

updateAttachmentIdAndMessageId

suspend fun

Synchronises the local database record’s attachment ID and message ID fields after the server has confirmed a message send. Called internally by the send pipeline; you should not need to call this directly.

Show Parameters

message

SceytMessage

required

The confirmed SceytMessage whose attachment IDs have been assigned by the server.

updateTransferDataByMsgTid

suspend fun

Updates the upload or download transfer state for an attachment identified by its parent message’s transaction ID. The UIKit calls this internally to persist progress, completion, or error states.

interactor.updateTransferDataByMsgTid(
    TransferData(
        messageTid   = pendingMessage.tid,
        progress     = 0.75f,
        state        = TransferState.Uploading,
        url          = null,
        filePath     = localPath
    )
)

Show Parameters

data

TransferData

required

A TransferData object containing the message tid, transfer progress (0.0–1.0), state, remote URL, and local file path.

updateAttachmentFilePathAndMetadata

suspend fun

Updates the local file path, file size, and metadata for an attachment in the database after a post-processing step (e.g. transcoding or resizing).

Show Parameters

messageTid

Long

required

The client-side transaction ID of the message whose attachment is being updated.

newPath

String

required

The absolute path to the processed file.

fileSize

Long

required

The size of the processed file in bytes.

metadata

String?

Updated metadata JSON string for the attachment (e.g. image dimensions, duration), or null to leave unchanged.

File Deduplication

getFileChecksumData

suspend fun → FileChecksumData?

Computes or retrieves the checksum data for a local file path. When SceytChatUIKitConfig.preventDuplicateAttachmentUpload is true, this is used to detect if the file has already been uploaded and reuse the existing URL.

val checksum: FileChecksumData? = interactor.getFileChecksumData(localFilePath)
if (checksum?.url != null) {
    // File already uploaded, reuse checksum.url
}

Show Parameters

filePath

String?

The absolute local file path to compute a checksum for. Returns null if the path is null or the file does not exist.

Link Previews

getLinkPreviewData

suspend fun → SceytResponse<LinkPreviewDetails>

Fetches Open Graph and other preview metadata for the given URL. The result is cached locally so subsequent calls for the same URL are served from the database.

when (val result = interactor.getLinkPreviewData("https://sceyt.com")) {
    is SceytResponse.Success -> showLinkPreview(result.data)
    is SceytResponse.Error   -> hideLinkPreview()
}

Show Parameters

link

String?

The URL string to fetch preview data for. Returns an error response if null or malformed.

upsertLinkPreviewData

suspend fun

Inserts or updates a LinkPreviewDetails record in the local database. Use this to pre-populate the cache with server-provided or externally fetched preview data.

interactor.upsertLinkPreviewData(
    LinkPreviewDetails(
        link        = "https://sceyt.com",
        title       = "Sceyt Chat",
        description = "In-app chat infrastructure",
        imageUrl    = "https://sceyt.com/og-image.png"
    )
)

Show Parameters

linkDetails

LinkPreviewDetails

required

The preview data to persist. The link field is used as the primary key.

Core API

Interactors

Styles & Theming

AttachmentInteractor — File and Media Attachment API

Paginating Attachments

Updating Attachment Metadata

File Deduplication

Link Previews

Build docs developers (and LLMs) love

Core API

Interactors

Styles & Theming

Documentation Index

​Paginating Attachments

​Updating Attachment Metadata

​File Deduplication

​Link Previews

Build docs developers (and LLMs) love

Paginating Attachments

Updating Attachment Metadata

File Deduplication

Link Previews