Function createDiffTrigger

packages/powersync-db-collection/src/powersync.ts:320–367

(options: {
        setupContext?: LockContext
        when: Record<DiffTriggerOperation, string>
        writeType: (rowId: string) => OperationType
        batchQuery: (
          lockContext: LockContext,
          batchSize: number,
          cursor: number,
        ) => Promise<Array<TableType>>
        onReady: () => void
      })

      }

      async function createDiffTrigger(options: {
        setupContext?: LockContext
        when: Record<DiffTriggerOperation, string>
        writeType: (rowId: string) => OperationType
        batchQuery: (
          lockContext: LockContext,
          batchSize: number,
          cursor: number,
        ) => Promise<Array<TableType>>
        onReady: () => void
      }) {
        const { setupContext, when, writeType, batchQuery, onReady } = options

        return await database.triggers.createDiffTrigger({
          source: viewName,
          destination: trackedTableName,
          setupContext,
          when,
          hooks: {
            beforeCreate: async (context) => {
              let currentBatchCount = syncBatchSize
              let cursor = 0
              while (currentBatchCount == syncBatchSize) {
                begin()

                const batchItems = await batchQuery(
                  context,
                  syncBatchSize,
                  cursor,
                )
                currentBatchCount = batchItems.length
                cursor += currentBatchCount
                for (const row of batchItems) {
                  write({
                    type: writeType(row.id),
                    value: deserializeSyncRow(row),
                  })
                }
                commit()
              }
              onReady()
              database.logger.info(
                `Sync is ready for ${viewName} into ${trackedTableName}`,
              )
            },
          },
        })
      }

      async function flushDiffRecords(): Promise<void> {
        await database