mdb-reader/lib/browser/data/complex/index.js

JavaScript library to read data from Access databases

import { Database } from "../../Database.js";
import { Table } from "../../Table.js";
import { ColumnTypes } from "../../types.js";
import { decodeAttachmentFileData } from "./attachment.js";
import { resolveFlatTableForComplexColumn } from "./utils.js";
/** Known attachment type column names; the FK column is the Long that is not one of these. */
const ATTACHMENT_TYPE_COLUMN_NAMES = new Set([
    "FileName",
    "FileType",
    "FileData",
    "FileURL",
    "FileTimeStamp",
    "FileFlags",
]);
/**
 * Reads a Complex (attachment) column: resolves the complex value FK to the flat table,
 * collects matching rows, and decodes each attachment's FileData.
 */
export function readComplex(buffer, column, database) {
    try {
        const complexTypeId = column.complex?.typeId;
        const tableDefinitionPage = column.complex?.tableDefinitionPage;
        if (complexTypeId === undefined || tableDefinitionPage === undefined) {
            throw new Error("Complex column is not valid");
        }
        const complexColumnDefinition = {
            ...column,
            complex: {
                typeId: complexTypeId,
                tableDefinitionPage,
            },
        };
        const foreignKey = buffer.readInt32LE(0);
        if (foreignKey <= 0) {
            throw new Error("Foreign key value is not valid");
        }
        const { tableName: flatTableName, firstPage: flatTableFirstPage } = resolveFlatTableForComplexColumn(database, complexColumnDefinition);
        const flatTable = new Table(flatTableName, database, flatTableFirstPage);
        const foreignKeyColumn = flatTable
            .getColumns()
            .find((c) => c.type === ColumnTypes.Long && !c.autoLong && !ATTACHMENT_TYPE_COLUMN_NAMES.has(c.name));
        if (!foreignKeyColumn) {
            throw new Error("Foreign key column not found");
        }
        const flatData = flatTable.getData();
        const matchingRows = flatData.filter((row) => row[foreignKeyColumn.name] === foreignKey);
        return matchingRows.map((row) => {
            const attachment = {
                name: row.FileName,
                type: row.FileType,
                data: decodeAttachmentFileData(row.FileData),
            };
            if (row.FileURL) {
                attachment.url = row.FileURL;
            }
            if (row.FileTimeStamp) {
                attachment.timestamp = row.FileTimeStamp;
            }
            if (row.FileFlags) {
                attachment.flags = row.FileFlags;
            }
            return attachment;
        });
    }
    catch (error) {
        throw new Error("Failed to read complex column", { cause: error });
    }
}