138 lines
3.3 KiB
JavaScript
138 lines
3.3 KiB
JavaScript
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import { Result } from "./result.mjs";
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import { PawSQLiteError } from "./pawsqlite_error.mjs";
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export class Transaction {
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constructor(dbName, adapter, enqueue, rollbackOnError=false) {
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this.dbName = dbName;
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this.adapter = adapter;
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this._rollbackOnError = rollbackOnError;
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this._enqueue = enqueue;
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this._completeCb = null;
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this._readyWait = null;
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this._ready = false;
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this._finalized = false;
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}
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async sql(sql, ...args) {
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if (this._finalized) {
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throw new PawSQLiteError("Transaction has already completed");
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}
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if (!this._ready) {
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await this._waitUntilReady();
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}
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try {
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return await this._executeSQL(sql, ...args);
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} catch (e) {
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if (this._rollbackOnError) {
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await this.rollback();
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}
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throw e;
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}
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}
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// Allow for slightly more complex parameter substitution.
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// Instances of "???" will be replaced by the same number of comma-separated
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// question marks as items in the corresponding nested parateter array
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// eg. buildQuery("SELECT (???) FROM ?", [["col1", "col2"], "table1"])
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// would output: ["SELECT (?, ?) FROM ?", ["col1", "col2", "table1"]]
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buildQuery(sql, ...args) {
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const parts = sql.split("???");
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const subParamLengths = args
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.filter(Array.isArray)
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.map((a) => a.length);
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if (parts.length !== subParamLengths.length + 1) {
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throw new PawSQLiteError("Unable to build query: sub-" +
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"paramters do not match sub-paramters in query");
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}
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const newQuery = parts.reduce((p1, p2, i) => {
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const length = subParamLengths[i - 1];
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return p1 + new Array(length).fill("?").join(", ") + p2;
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});
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const flatParams = args.reduce((acc, v) => {
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if (Array.isArray(v)) {
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Array.prototype.push.apply(acc, v);
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} else {
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acc.push(v);
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}
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return acc;
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}, []);
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return [newQuery, ...flatParams];
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}
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commit() {
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return this._complete("COMMIT");
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}
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rollback() {
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return this._complete("ROLLBACK");
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}
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async _waitUntilReady() {
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if (!this._readyWait) {
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this._readyWait = (async () => {
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this._completeCb = await this._enqueue();
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await this._begin();
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this._ready = true;
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})();
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}
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await this._readyWait;
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}
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async _executeSQL(sql, ...args) {
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const reg = /^\s*(BEGIN|END|COMMIT|ROLLBACK)(?:[^A-Z]|$)/i;
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const match = reg.exec(sql);
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if (match) {
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const statement = match[1].toUpperCase();
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throw new PawSQLiteError("Manually managing transactions is " +
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"forbidden. Found: \"" + statement + "\" statement.");
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}
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const result = await this.adapter.sql(this.dbName,
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...this.buildQuery(sql, ...args));
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return new Result(result);
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}
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async _begin() {
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const result = await this.adapter.sql(this.dbName, "BEGIN");
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}
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async _complete(sql) {
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if (this._finalized) {
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throw new PawSQLiteError("Transaction has already completed");
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}
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this._finalized = true;
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if (!this._readyWait) {
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// Transaction was unused
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return;
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} else if (!this._ready) {
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await this._waitUntilReady();
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}
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let result;
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let error;
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try {
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result = await this.adapter.sql(this.dbName, sql);
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} catch (e) {
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error = e;
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}
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this._completeCb();
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if (error) {
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throw error;
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}
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return new Result(result);
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}
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}
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