csv-database/database/init.js

lightweight CSV database

const fs = require("fs");
const doesFileExist = (filename) => new Promise((resolve, reject) => {
    fs.exists(filename, resolve);
});
const createFile = (filename, data) => new Promise((resolve, reject) => {
    fs.writeFile(filename, data, err => {
        err ? reject(err) : resolve();
    });
});
const createFileIfNotExist = async (filename, model, delimiter) => {
    try {
        if (!await doesFileExist(filename)) {
            const headers = model.reduce((header, cell) => header + delimiter + cell);
            await createFile(filename, headers);
        }
    }
    catch (err) {
        throw new Error("error creating csv file : " + err);
    }
};
const hasSameModel = (obj, model) => {
    const objKeys = Object.keys(obj);
    const objHasKey = key => objKeys.find(k => k === key);
    for (const key of model) {
        if (!objHasKey(key))
            return false;
    }
    // if length is different, arrays are not equal
    return objKeys.length === model.length;
};
const validate = async (parser, model) => {
    let validated = false;
    // stop at first line once model has been validated
    const checkModel = data => {
        if (!validated && !hasSameModel(data, model))
            throw new Error("csv model doesn't correspond");
        validated = true;
    };
    const events = {
        onData: checkModel
    };
    return parser.read(events);
};
const initDb = async (filename, model, delimiter, parser) => {
    await createFileIfNotExist(filename, model, delimiter);
    await validate(parser, model);
};
module.exports = initDb;