130 lines
3.8 KiB
JavaScript
130 lines
3.8 KiB
JavaScript
const cds = require("@sap/cds");
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const FIRST_INDEX = 0;
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const ZERO_VALUE = 0;
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const SECOND_INDEX = 1;
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const ID_IF_NOT_FOUND = "ID";
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const SRC_STORAGE_NAME = "sqlite:chinook.db";
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const camelCaseToSnake = (str) =>
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str.replace(
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/[a-z][A-Z]/g,
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(letters) =>
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`${letters[FIRST_INDEX].toLowerCase()}_${letters[
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SECOND_INDEX
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].toLowerCase()}`
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);
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const omitID = (str) => {
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return str.replace(/_ID$/g, "");
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};
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const omitId = (str) => {
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return str.replace(/Id$/g, "");
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};
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const chooseFromTargetColumns = (targetColumns) => {
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return (srcColumn) => {
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const result = targetColumns.find((targetColumn) => {
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const one = omitId(srcColumn).toUpperCase();
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const two = omitID(targetColumn).toUpperCase();
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if (one === two) {
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return true;
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}
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return false;
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});
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return result ? result : ID_IF_NOT_FOUND;
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};
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};
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const reorderTargetColumns = (srcColumns, targetColumns) => {
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const mapColumn = chooseFromTargetColumns(targetColumns);
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return srcColumns.map(mapColumn);
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};
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const elementsToColumns = (elements) => {
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return Object.values(elements).map((element) =>
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element.target ? `${element.name}_ID` : element.name
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);
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};
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const constructInsertQuery = (targetEntityName) => {
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return (row, columns) =>
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INSERT.into(targetEntityName).columns(columns).rows(row);
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};
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/**
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* The MAIN ISSUE such import is that it depends on:
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* - snake case table names
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* - camel case column names
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* of chinook.db
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* There is 'Launch import' task in .vscode folder for debugging.
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*/
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async function importData(targetDb) {
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try {
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const srcStorage = await cds.connect.to(SRC_STORAGE_NAME);
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const targetCSNEntities = Object.values(targetDb.entities);
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const targetCSNEntitiesNames = Object.keys(targetDb.entities);
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const someEntry = await targetDb.run(
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SELECT.one(targetCSNEntitiesNames[FIRST_INDEX])
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);
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if (!!someEntry) {
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return;
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}
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for (index in targetCSNEntities) {
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const targetEntityName = targetCSNEntitiesNames[index];
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console.log(`[LOG]: Processing ${targetEntityName}`);
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const { elements } = targetCSNEntities[index];
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const targetColumns = elementsToColumns(elements); // e.g. ['ID', ..., 'total', 'customer_ID']
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const srcEntityName = camelCaseToSnake(targetEntityName);
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const insertQuery = constructInsertQuery(targetEntityName);
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let srcResultRows;
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try {
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srcResultRows = await srcStorage.run(`
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SELECT * from ${srcEntityName}
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`); // e.g. [ { AlbumId:1, ArtistId:1, Title:'some' }, ... ]
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} catch (e) {
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console.log("[ERROR]: while trying to read source table", e.message);
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continue;
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}
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if (!srcResultRows || srcResultRows.length < ZERO_VALUE) {
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console.log(
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`[LOG] Skipping ${targetEntityName}.
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There is no data provided in ${SRC_STORAGE_NAME}, ${srcEntityName}`
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);
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continue;
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}
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const srcColumns = Object.keys(srcResultRows[FIRST_INDEX]);
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const columns = reorderTargetColumns(srcColumns, targetColumns);
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if (new Set(columns).size !== columns.length) {
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throw new Error(
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`Some ${targetEntityName} column name is mismatched in ${SRC_STORAGE_NAME} ${srcEntityName}`
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);
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}
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// for mock auth
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if (srcEntityName === "Employees" || srcEntityName === "Customers") {
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columns.push("password");
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srcResultRows = srcResultRows.map((row) => ({
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...row,
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password: "some",
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}));
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}
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const transaction = await targetDb.tx();
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await transaction.run(
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srcResultRows.map((row) => insertQuery(Object.values(row), columns))
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);
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await transaction.commit();
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}
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console.log("[LOG]: ", "Import completed");
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} catch (errors) {
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console.error(errors);
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}
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}
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module.exports = { importData };
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