arangojs/transaction.d.ts

import { Database } from "./database.js";
/**
 * Indicates whether the given value represents a {@link Transaction}.
 *
 * @param transaction - A value that might be a transaction.
 */
export declare function isArangoTransaction(transaction: any): transaction is Transaction;
/**
 * Options for how the transaction should be committed.
 */
export type TransactionCommitOptions = {
    /**
     * If set to `true`, the request will explicitly permit ArangoDB to return a
     * potentially dirty or stale result and arangojs will load balance the
     * request without distinguishing between leaders and followers.
     */
    allowDirtyRead?: boolean;
};
/**
 * Options for how the transaction should be aborted.
 */
export type TransactionAbortOptions = {
    /**
     * If set to `true`, the request will explicitly permit ArangoDB to return a
     * potentially dirty or stale result and arangojs will load balance the
     * request without distinguishing between leaders and followers.
     */
    allowDirtyRead?: boolean;
};
/**
 * Status of a given transaction.
 *
 * See also {@link database.TransactionDetails}.
 */
export type TransactionStatus = {
    /**
     * Unique identifier of the transaction.
     */
    id: string;
    /**
     * Status of the transaction.
     */
    status: "running" | "committed" | "aborted";
};
/**
 * Represents a streaming transaction in a {@link database.Database}.
 */
export declare class Transaction {
    protected _db: Database;
    protected _id: string;
    /**
     * @internal
     */
    constructor(db: Database, id: string);
    /**
     * @internal
     *
     * Indicates that this object represents an ArangoDB transaction.
     */
    get isArangoTransaction(): true;
    /**
     * Unique identifier of this transaction.
     *
     * See {@link database.Database#transaction}.
     */
    get id(): string;
    /**
     * Checks whether the transaction exists.
     *
     * @example
     * ```js
     * const db = new Database();
     * const trx = db.transaction("some-transaction");
     * const result = await trx.exists();
     * // result indicates whether the transaction exists
     * ```
     */
    exists(): Promise<boolean>;
    /**
     * Retrieves general information about the transaction.
     *
     * @example
     * ```js
     * const db = new Database();
     * const col = db.collection("some-collection");
     * const trx = db.beginTransaction(col);
     * await trx.step(() => col.save({ hello: "world" }));
     * const info = await trx.get();
     * // the transaction exists
     * ```
     */
    get(): Promise<TransactionStatus>;
    /**
     * Attempts to commit the transaction to the databases.
     *
     * @param options - Options for comitting the transaction.
     *
     * @example
     * ```js
     * const db = new Database();
     * const col = db.collection("some-collection");
     * const trx = db.beginTransaction(col);
     * await trx.step(() => col.save({ hello: "world" }));
     * const result = await trx.commit();
     * // result indicates the updated transaction status
     * ```
     */
    commit(options?: TransactionCommitOptions): Promise<TransactionStatus>;
    /**
     * Attempts to abort the transaction to the databases.
     *
     * @param options - Options for aborting the transaction.
     *
     * @example
     * ```js
     * const db = new Database();
     * const col = db.collection("some-collection");
     * const trx = db.beginTransaction(col);
     * await trx.step(() => col.save({ hello: "world" }));
     * const result = await trx.abort();
     * // result indicates the updated transaction status
     * ```
     */
    abort(options?: TransactionAbortOptions): Promise<TransactionStatus>;
    /**
     * Executes the given function locally as a single step of the transaction.
     *
     * @param T - Type of the callback's returned promise.
     * @param callback - Callback function returning a promise.
     *
     * **Warning**: The callback function should wrap a single call of an async
     * arangojs method (e.g. a method on a `Collection` object of a collection
     * that is involved in the transaction or the `db.query` method).
     * If the callback function is async, only the first promise-returning (or
     * async) method call will be executed as part of the transaction. See the
     * examples below for how to avoid common mistakes when using this method.
     *
     * **Note**: Avoid defining the callback as an async function if possible
     * as arangojs will throw an error if the callback did not return a promise.
     * Async functions will return an empty promise by default, making it harder
     * to notice if you forgot to return something from the callback.
     *
     * **Note**: Although almost anything can be wrapped in a callback and passed
     * to this method, that does not guarantee ArangoDB can actually do it in a
     * transaction. Refer to the ArangoDB documentation if you are unsure whether
     * a given operation can be executed as part of a transaction. Generally any
     * modification or retrieval of data is eligible but modifications of
     * collections or databases are not.
     *
     * @example
     * ```js
     * const db = new Database();
     * const vertices = db.collection("vertices");
     * const edges = db.collection("edges");
     * const trx = await db.beginTransaction({ write: [vertices, edges] });
     *
     * // The following code will be part of the transaction
     * const left = await trx.step(() => vertices.save({ label: "left" }));
     * const right = await trx.step(() => vertices.save({ label: "right" }));
     *
     * // Results from preceding actions can be used normally
     * await trx.step(() => edges.save({
     *   _from: left._id,
     *   _to: right._id,
     *   data: "potato"
     * }));
     *
     * // Transaction must be committed for changes to take effected
     * // Always call either trx.commit or trx.abort to end a transaction
     * await trx.commit();
     * ```
     *
     * @example
     * ```js
     * // BAD! If the callback is an async function it must only use await once!
     * await trx.step(async () => {
     *   await collection.save(data);
     *   await collection.save(moreData); // WRONG
     * });
     *
     * // BAD! Callback function must use only one arangojs call!
     * await trx.step(() => {
     *  return collection.save(data)
     *    .then(() => collection.save(moreData)); // WRONG
     * });
     *
     * // BETTER: Wrap every arangojs method call that should be part of the
     * // transaction in a separate `trx.step` call
     * await trx.step(() => collection.save(data));
     * await trx.step(() => collection.save(moreData));
     * ```
     *
     * @example
     * ```js
     * // BAD! If the callback is an async function it must not await before
     * // calling an arangojs method!
     * await trx.step(async () => {
     *   await doSomethingElse();
     *   return collection.save(data); // WRONG
     * });
     *
     * // BAD! Any arangojs inside the callback must not happen inside a promise
     * // method!
     * await trx.step(() => {
     *   return doSomethingElse()
     *     .then(() => collection.save(data)); // WRONG
     * });
     *
     * // BETTER: Perform any async logic needed outside the `trx.step` call
     * await doSomethingElse();
     * await trx.step(() => collection.save(data));
     *
     * // OKAY: You can perform async logic in the callback after the arangojs
     * // method call as long as it does not involve additional arangojs method
     * // calls, but this makes it easy to make mistakes later
     * await trx.step(async () => {
     *   await collection.save(data);
     *   await doSomethingDifferent(); // no arangojs method calls allowed
     * });
     * ```
     *
     * @example
     * ```js
     * // BAD! The callback should not use any functions that themselves use any
     * // arangojs methods!
     * async function saveSomeData() {
     *   await collection.save(data);
     *   await collection.save(moreData);
     * }
     * await trx.step(() => saveSomeData()); // WRONG
     *
     * // BETTER: Pass the transaction to functions that need to call arangojs
     * // methods inside a transaction
     * async function saveSomeData(trx) {
     *   await trx.step(() => collection.save(data));
     *   await trx.step(() => collection.save(moreData));
     * }
     * await saveSomeData(); // no `trx.step` call needed
     * ```
     *
     * @example
     * ```js
     * // BAD! You must wait for the promise to resolve (or await on the
     * // `trx.step` call) before calling `trx.step` again!
     * trx.step(() => collection.save(data)); // WRONG
     * await trx.step(() => collection.save(moreData));
     *
     * // BAD! The trx.step callback can not make multiple calls to async arangojs
     * // methods, not even using Promise.all!
     * await trx.step(() => Promise.all([ // WRONG
     *   collection.save(data),
     *   collection.save(moreData),
     * ]));
     *
     * // BAD! Multiple `trx.step` calls can not run in parallel!
     * await Promise.all([ // WRONG
     *   trx.step(() => collection.save(data)),
     *   trx.step(() => collection.save(moreData)),
     * ]));
     *
     * // BETTER: Always call `trx.step` sequentially, one after the other
     * await trx.step(() => collection.save(data));
     * await trx.step(() => collection.save(moreData));
     *
     * // OKAY: The then callback can be used if async/await is not available
     * trx.step(() => collection.save(data))
     *   .then(() => trx.step(() => collection.save(moreData)));
     * ```
     *
     * @example
     * ```js
     * // BAD! The callback will return an empty promise that resolves before
     * // the inner arangojs method call has even talked to ArangoDB!
     * await trx.step(async () => {
     *   collection.save(data); // WRONG
     * });
     *
     * // BETTER: Use an arrow function so you don't forget to return
     * await trx.step(() => collection.save(data));
     *
     * // OKAY: Remember to always return when using a function body
     * await trx.step(() => {
     *   return collection.save(data); // easy to forget!
     * });
     *
     * // OKAY: You do not have to use arrow functions but it helps
     * await trx.step(function () {
     *   return collection.save(data);
     * });
     * ```
     *
     * @example
     * ```js
     * // BAD! You can not pass promises instead of a callback!
     * await trx.step(collection.save(data)); // WRONG
     *
     * // BETTER: Wrap the code in a function and pass the function instead
     * await trx.step(() => collection.save(data));
     * ```
     *
     * @example
     * ```js
     * // WORSE: Calls to non-async arangojs methods don't need to be performed
     * // as part of a transaction
     * const collection = await trx.step(() => db.collection("my-documents"));
     *
     * // BETTER: If an arangojs method is not async and doesn't return promises,
     * // call it without `trx.step`
     * const collection = db.collection("my-documents");
     * ```
     */
    step<T>(callback: () => Promise<T>): Promise<T>;
}
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