data-access

This library provides a database access class to enhance the standard database client API. It currently supports MongoDB and Cassandra DB.

The class must be subclassed to select a specific table/collection and should be instantiated on demand per client request. Multiple instances will reuse the same underlying database connection pool.

Exports

• Class CassandraDatabaseAccess
• Class MongoDatabaseAccess
• interface InsertResult
• function initDb(dbName: string, options: any): void

Initialization

import { initDb } from 'data-access'

const dbParams: any = {
    hostname: 'mongodb://127:0.0.1:27017',
    auth: {
        username: process.env.DB_USER,
        password: process.env.DB_PASSWORD
    },
};

initDb('mongodb', dbParams);

Usage

import { MongoDatabaseAccess } from 'data-access';

class UserCollectionAccess extends MongoDatabaseAccess {
    private _account: string = '';

    constructor(account: string, username: string) {
        super('main-database', 'users', username);

        this._account = account;
    }

    public changeUserName(firstname: string, lastname: string): Promise<any> {
        return this.update(
            { account: this._account, email: this._username },
            { firstname, lastname }
        );
    }
}

function updateUserHandler(input, context, ext) {
    const db: UserTableAccess = new UserTableAccess(input.account, input.user);

    return db.changeUserName(input.firstname, input.lastname);
}

MongoDatabaseAccess class methods

The listed methods are marked as protected and should only be called within a child class. All options arguments are passed directly to the mongodb driver.

MongoDatabaseAccess.constructor(dbName: string, collectionName: string, username: string)

Each subclass should be designed to access one database collection. The username is required for auditing.

Query execution

MongoDatabaseAccess.find(filter: object, [options: object])

Selects documents matching filter, filtering out any documents where __status = 'deleted' (in memory, after the database results are retrieved). filter may be any valid MongoDB find filter.

Returns: a Promise resolving to an array of documents.

MongoDatabaseAccess.findAll(filter: object, [options: object])

Selects documents matching filter and immediately returns a raw MongoDB Cursor, for improved read performance.

Returns: an instance of mongo.Cursor.

MongoDatabaseAccess.insert(documents: any[], [options: object])

Inserts one or more documents into the table. The interface will automatically add auditing and version fields (this cannot currently be disabled).

Returns: a Promise resolving to a mongodb write operation result.

MongoDatabaseAccess.update(filter: object, document: object, [options: object])

Applies the update parameter document to the document matching filter. Allows MongoDB update-specific fields.

This method uses version checking, requiring filter to include a __version value to match against the updated document. A new random __version value will be set on the document, along with updated __modifiedBy and __modifiedOn values.

Returns: a Promise resolving to a mongodb write operation result.

MongoDatabaseAccess.updateUnsafe(filter: object, values: object, [options: object])

Applies the update parameter document to all documents matching filter. Allows MongoDB update-specific fields.

No version checking is used, and multiple documents will be updated if they match filter. New __version, __modifiedBy, and __modifiedOn values will be set on all updated documents.

Returns: a Promise resolving to a mongodb write operation result.

MongoDatabaseAccess.remove(filter: object, [options: object])

Performs a soft delete on one document matching filter, setting the document's __status value to 'deleted'.

This method uses version checking, requiring filter to include a __version value to match against the updated document. A new random __version value will be set on the document, along with updated __modifiedBy and __modifiedOn values.

Returns: a Promise resolving to a mongodb write operation result.

MongoDatabaseAccess.removeUnsafe(filter: object, [options: object])

Performs a soft delete on all documents matching filter, setting the documents' __status value to 'deleted'.

No version checking is used. A new random __version value will be set on every updated document, along with updated __modifiedBy and __modifiedOn values.

Returns: a Promise resolving to a mongodb write operation result.

MongoDatabaseAccess.removeHard(filter: object, [options: object])

Permanently deletes all documents matching filter.

Returns: a Promise resolving to a mongodb write operation result.

See packaged API documentation for raw query generation methods.