lolo-backend/lib/services.js

Lolo Backend is a REST Framework and provides an automatic asynchronous CRUD backend server generator based on your models' definitions and validation rules for Node.js and MongoDB.

/*!
 * lolo-backend
 * Copyright(c) 2021 Camilo Pifano Herrera
 * MIT Licensed
 */
//--------------------------------------------------------------------------------------------------------------------//
// SERVICES:
// This file defines the functions of general use (services).
//--------------------------------------------------------------------------------------------------------------------//

//Import external modules:
const path      = require('path');
const fs        = require('fs');
const yaml      = require('js-yaml');
const mongoose  = require('mongoose');

//--------------------------------------------------------------------------------------------------------------------//
// GET FILE SETTINGS:
// This function reads the settings file content (YAML) and returns it in an object.
//--------------------------------------------------------------------------------------------------------------------//
function getFileSettings(){
    //Read YAML settings file:
    try {
        let fileContents = fs.readFileSync(path.resolve('./', 'settings.yaml'), 'utf8');
        return yaml.load(fileContents);
    } catch (err) {
        console.log('An error occurred while trying to read the settings.yaml file.');
        console.error(err);
    }
}
//--------------------------------------------------------------------------------------------------------------------//

//--------------------------------------------------------------------------------------------------------------------//
// REMOVE ITEM FROM ARRAY:
// Function to remove elements from an array.
//--------------------------------------------------------------------------------------------------------------------//
function removeItemFromArray(array, item){
    let indice = array.indexOf(item);
    array.splice(indice, 1);
}
//--------------------------------------------------------------------------------------------------------------------//

//--------------------------------------------------------------------------------------------------------------------//
// VALIDATE FORMATTED PROJ:
// Validate and format MongoDB query projection.
//--------------------------------------------------------------------------------------------------------------------//
function validateFormattedProj(proj){
    //Initialize final projection variable:
    let formatted_proj = new Object();

    //Format data projection:
    if(proj && Object.keys(proj).length >= 1){
        Object.entries(proj).forEach(([key, value]) => {
            //Parse projection value (string) to integer (base 10):
            formatted_proj[key] = parseInt(value, 10);
        });

        //Return formatted projection:
        return formatted_proj;
    } else {
        //Return empty string:
        return '';
    }
}
//--------------------------------------------------------------------------------------------------------------------//

//--------------------------------------------------------------------------------------------------------------------//
// VALIDATE REQUEST ID:
// Validate request ID (MongoID).
//--------------------------------------------------------------------------------------------------------------------//
function validateRequestID(req, res, currentLang){
    //Validate the existence of the ID field in the request:
    if (!req.body.id && !req.query.id) {
        res.status(400).json({ success: false,  message: currentLang.db.empty_id });
        return false;
    } else {
        //Check that the entered ID is valid for MongoDB:
        if(mongoose.Types.ObjectId.isValid(req.body.id) || mongoose.Types.ObjectId.isValid(req.query.id)) {
            return true;
        } else {
            res.status(400).json({ success: false, message: currentLang.db.invalid_id });
            return false;
        }
    }
}
//--------------------------------------------------------------------------------------------------------------------//

//--------------------------------------------------------------------------------------------------------------------//
// COMMON RESPONSE:
// Most common response function (only two way).
//--------------------------------------------------------------------------------------------------------------------//
function commonResponse(err, data, currentLang){
    //Validate errors in the query:
    if(err){
        //Set error message:
        errorMessage = { success: false, message: currentLang.db.query_error, error: err.message };

        //Send error message to console:
        console.error(errorMessage);

        //Return error message (HTML Response):
        return errorMessage;
    } else if(data){
        //Return result (HTML Response):
        return { success: true, data: data };
    } else {
        //Return result NO data (HTML Response):
        return { success: true, message: currentLang.db.query_no_data, data: {} };
    }
}
//--------------------------------------------------------------------------------------------------------------------//

//--------------------------------------------------------------------------------------------------------------------//
// GET SCHEMA KEYS:
// This function obtain the keys of the current model, with or without modifiable elements.
// The notAllowedKeys (boolean, default false), parameter defines whether or not it will return the keys of the model
// that should NOT be modified manually.
//--------------------------------------------------------------------------------------------------------------------//
function getSchemaKeys(current, notAllowedKeys = false){
    //Get keys from current schema:
    //schemaKeys defines the list of modifiable elements of the object.
    const schemaKeys = Object.keys(current.Schema.paths);

    //Remove NON-modifiable elements. Only if requested:
    if(notAllowedKeys === true){
        removeItemFromArray(schemaKeys, '_id');
        removeItemFromArray(schemaKeys, 'updatedAt');
        removeItemFromArray(schemaKeys, 'createdAt');
        removeItemFromArray(schemaKeys, '__v');
    }
    //Return result:
    return schemaKeys;
}
//--------------------------------------------------------------------------------------------------------------------//

//--------------------------------------------------------------------------------------------------------------------//
// SEND CONSOLE MESSAGE:
// This function implements the verbose logging mode, sending information messages to the console.
//--------------------------------------------------------------------------------------------------------------------//
function sendConsoleMessage(req){
    console.log(req.method + ' request received [ ' + req.protocol + '://' + req.hostname + req.originalUrl + ' ] from ' + req.ip);
}
//--------------------------------------------------------------------------------------------------------------------//

//--------------------------------------------------------------------------------------------------------------------//
// Export service module:
//--------------------------------------------------------------------------------------------------------------------//
module.exports = {
    getFileSettings,
    removeItemFromArray,
    validateFormattedProj,
    validateRequestID,
    commonResponse,
    getSchemaKeys,
    sendConsoleMessage
};
//--------------------------------------------------------------------------------------------------------------------//