timw4mail/node-query

/**
 * Class that wraps database connection libraries
 *
 * @private
 * @param  {Promise} instance - The connection object
 */
class Adapter {
    /**
     * Invoke an adapter
     *
     * @constructor
     * @param  {Promise} instance - Promise holding connection object
     */
    constructor (instance) {
        this.instance = instance;
    }

    /**
     * Run the sql query as a prepared statement
     *
     * @param {String} sql - The sql with placeholders
     * @param {Array} params - The values to insert into the query
     * @return {Promise} - returns a promise resolving to the result of the database query
     */
    execute (sql, params) {
        throw new Error('Correct adapter not defined for query execution');
    }

    /**
     * Transform the adapter's result into a standard format
     *
     * @param {*} originalResult - the original result object from the driver
     * @return {Result} - the new result object
     */
    transformResult (originalResult) {
        throw new Error('Result transformer method not defined for current adapter');
    }

    /**
     * Close the current database connection
     * @return {void}
     */
    close () {
        this.instance.then(conn => conn.end());
    }
}

module.exports = Adapter;