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recursive function to retrieve nested category in nodejs and mongodb

I have category with below schema for tree structure data:
const mongoose = require("mongoose")
const CategorySchema = new mongoose.Schema(
{
name: {type:String, required: true},
parent_id: { type: mongoose.Schema.Types.ObjectId, default: null},
slug: { type: String, required: true, unique: true}
}
);
module.exports = mongoose.model("Category", CategorySchema)
Router api call to get all category:
//GET ALL Category
router.get("/", async (req,res) => {
try {
const categories = await Category.find({});
if (!categories)
{
return [];
}
return nestedCategories(categories);
} catch (err) {
console.log(err);
}
})
Below is the recursive function:
const nestedCategories = (categories, parentId = null) => {
const categoryList = [];
let category;
if (parentId == null) {
category = categories.filter(cat => cat.parent_id == null);
} else {
category = categories.filter(cat => String(cat.parent_id) == String(parentId));
}
for (let cate of category) {
categoryList.push({
_id: cate._id,
name: cate.name,
slug: cate.slug,
children: nestedCategories(categories, cate._id)
})
}
return categoryList;
}
module.exports = { nestedCategories }
Using postman, I have requested a api call to get router function, it causes infinite loop. Do I need to add break point in recursive function?

Sequelize - Foreign keys are always null

Description
I'm starting to learn how to use Sequelize and I've run into an issue with foreign key relationships for one of my tables. I have three tables: Users, Projects, Times. Users and Projects have a Many to One relationship with Times.
Time.belongsTo(User)
Time.belongsTo(Project)
User.hasMany(Time)
Project.hasMany(Time)
After I create an entry in the Times table and then fetch it the resulting record always has Nulls for the two foreign keys.
db.Time.findAll().then(result => {
res.status(200).send(JSON.stringify(result))
})
Model
const {Sequelize, DataTypes} = require('sequelize');
const sequelize = new Sequelize('sqlite::memory:');
const User = sequelize.define('User', {
email: {
type: DataTypes.STRING,
allowNull: false,
unique: true
},
password: {
type: DataTypes.STRING,
allowNull: false
}
});
const Project = sequelize.define('Project', {
name: {
type: DataTypes.STRING,
allowNull: false
}
});
const Time = sequelize.define('Time', {
description: {
type: DataTypes.STRING,
allowNull: false
},
start: {
type: DataTypes.STRING,
allowNull: false
},
stop: {
type: DataTypes.STRING,
allowNull: false
}
});
console.log('Setting up Models')
Time.belongsTo(User)
Time.belongsTo(Project)
User.hasMany(Time)
Project.hasMany(Time)
const db = {
"sequelize": sequelize,
"User": User,
"Project": Project,
"Time": Time
}
exports.User = User;
exports.Project = Project;
exports.Time = Time;
exports.db = db;
Populating with Default Data
const {data} = require('./data')
const {db} = require('../data/models')
const dbHelper = {
connectDB: () => {
return new Promise((resolve, reject) => {
db.sequelize.authenticate().then(() => {
resolve(db)
}).catch((e) => {
reject(e);
})
})
},
hydrateDB: (db) => {
return new Promise((resolve, reject) => {
try {
db.sequelize.sync().then(() => {
hydrateUser(db).then(() => {
hydrateProject(db).then(() => {
hydrateTime(db).then(() => {
resolve()
})
})
})
})
} catch (e) {
reject(e)
}
})
}
}
const hydrateUser = (db) => {
return new Promise(resolve => {
data.user.forEach((datum) => {
db.User.create(datum).then(() => {
resolve()
})
})
})
}
const hydrateProject = (db) => {
return new Promise(resolve => {
data.project.forEach((datum) => {
db.Project.create(datum).then(() => {
resolve()
})
})
})
}
const hydrateTime = (db) => {
return new Promise(resolve => {
data.time.forEach((datum) => {
db.Time.create({
description: datum.description,
start: datum.start,
stop: datum.stop,
userId: 1,
projectId: 1
}).then(() => {
resolve()
})
})
})
}
exports.dbHelper = dbHelper;

You indicated fields in camel case here:
userId: 1,
projectId: 1
And actual fields created for Time are in pascal case as you showed in the screenshot.
So just correct names:
db.Time.create({
description: datum.description,
start: datum.start,
stop: datum.stop,
UserId: 1,
ProjectId: 1
}).then(() => {
resolve()
})

Access array values after knex SELECT

I have the following code snippet in an Electron app to retrieve a given column in a sqlite3 database:
database.js
var database = require("knex")({
client: "sqlite3",
connection: {
filename: path.join(__dirname, 'db/food.db')
},
useNullAsDefault: true
});
const fetchItems = (colName) => {
let itemList = database.select(colName).from('food')
itemList.then(() => {
// console.log(itemList);
return itemList;
}).catch((err) => {
console.log(err)
return [];
})
}
When I try accessing the array itemList, I got a message undefined. When I try printing it out to console, it shows lengthy info of the database object as following:
Builder [object] {
client: Client_SQLite3 {
config: { client: 'sqlite3', connection: [Object], useNullAsDefault: true },
logger: Logger {
_inspectionDepth: 5,
_enableColors: true,
_debug: undefined,
_warn: undefined,
_error: undefined,
_deprecate: undefined
},
connectionSettings: {
filename: '/home/.../db/food.db'
},
connectionConfigExpirationChecker: null,
driver: {
Database: [Function: Database],
Statement: [Function: Statement],
Backup: [Function: Backup],
OPEN_READONLY: 1,
...
How do I go about accessing the array (i.e. column) of values? Thanks.
Update: here is how I call this fetchItems function in main.js.
const database = require('./database');
ipcMain.on("showItemsButtonClicked", function () {
let itemList = database.fetchItems('food_name');
itemList.then(() => {
mainWindow.webContents.send("itemsRetrieved", itemList);
})
console.log(itemList);
});

I think you are using the wrong syntax.
const fetchItems = (colName) => {
let itemList = database.select(colName).from('food').then((res) => {
// console.log(res);
return res;
}).catch((err) => {
console.log(err)
return [];
})
return itemList
}
Using async await:
const fetchItems = async(colName) => {
try {
let itemList = await database.select(colName).from('food')
return itemList
} catch(err) {
console.log(err)
return [];
}
}

MongoDB inserting data only if it don't exist (in Javascript)

I'm creating a web scraper and I need to store my data in MongoDB. I scrape some data and store it in a variable call item. I also don't to add a data to the database if it already exist. so here is my resultAnalysis.mjs file that is supposed to do that. What should I change in this code, because it don't insert data and also throw error :
TypeError: Cannot destructure property 'lotNumber' of 'item' as it is undefined.
at file:///Users/AlainMolleyres/Desktop/scraper_V1/resultsAnalysis.mjs:48:11
at runMicrotasks (<anonymous>)
at processTicksAndRejections (internal/process/task_queues.js:93:5)
Here is my code
resultsAnalysis.mjs
mongoose
.connect(mongoURI, { useNewUrlParser: true })
.then(() => console.log("MongoDB connected"))
.catch((err) => console.error(err));
export const compareAndSaveResults = (item) => {
try {
const Schema = mongoose.Schema;
const lotSchema = new Schema({
lotNumber: {},
artistName: {},
artworkNameOriginal: {},
pictureUrl: {},
artworkDate: {},
signed: {},
titled: {},
technic: {},
literature: {},
provenance: {},
dimension: {},
lowEstimation: {},
highEstimation: {},
currency: {},
soldPrice: {},
lotUrl: {},
});
const lot = mongoose.model("lot", lotSchema);
lot
.find({}, function (err, lotList) {
return lotList;
})
.then((lotList) => {
if (lotList == "") {
console.log(`A new data was created:\n${JSON.stringify(item)}`);
const newLot = new lot(item);
return newLot.save().catch((err) => console.log(err));
}
const {
lotNumber,
artistName,
artworkNameOriginal,
pictureUrl,
artworkDate,
signed,
titled,
technic,
literature,
provenance,
lowEstimation,
highEstimation,
currency,
soldPrice,
dimensionInCm,
lotUrl,
} = item;
const dbId = lotList[0]._id;
const dbArtworkNameOriginal = lotList[0].artworkNameOriginal;
const dbLotUrl = newsList[0].lotUrl;
let catchDifference = false;
if (dbArtworkNameOriginal !== artworkNameOriginal) {
catchDifference = true;
} else {
dbLotUrl.forEach((elem, i) => {
if (elem !== lotUrl[i]) catchDifference = true;
});
}
if (catchDifference) {
console.log("A new evidence was found, updating database...");
mongoose.set("useFindAndModify", false);
return News.findOneAndUpdate({ _id: dbId }, item);
}
console.log("File is equal to page, no lot to report");
})
.then(() => {
mongoose.disconnect();
})
.catch((err) => console.log(err));
} catch (err) {
console.error(err);
}
};
``

eslint arrow-body-style issue

I configured my eslint so it uses the arrow-body-style as needed:
arrow-body-style: ["error", "as-needed"]
But I'm getting an error below for some reason.
router.get('/', (req, res, next) => {
Product.find({})
.select('name price _id')
.then(items => {
const response = {
count: items.length,
products: items.map(item => { // eslint points the error here
return {
name: item.name,
price: item.price,
_id: item._id,
request: {
type: 'GET',
url: `http://localhost:3000/products/${item._id}`
}
};
})
};
res.status(200).json(response);
})
.catch(error => {
console.log(error);
res.status(500).json({ message: 'Server error' });
});
});
How exactly am I supposed to re-write my code?

Using arrow-body-style: ["error", "as-needed"] configuration is redundant as it is the default behaviour. You don't need setting it again as it is already set as the default form.
as-needed
Examples of incorrect code for this rule with the default "as-needed" option:
/*eslint arrow-body-style: ["error", "as-needed"]*/
/*eslint-env es6*/
let foo = () => {
return 0;
};
let foo = () => {
return {
bar: {
foo: 1,
bar: 2,
}
};
};
Examples of correct code for this rule with the default "as-needed" option:
/*eslint arrow-body-style: ["error", "as-needed"]*/
/*eslint-env es6*/
let foo = () => 0;
let foo = (retv, name) => {
retv[name] = true;
return retv;
};
let foo = () => ({
bar: {
foo: 1,
bar: 2,
}
});
let foo = () => { bar(); };
let foo = () => {};
let foo = () => { /* do nothing */ };
let foo = () => {
// do nothing.
};
let foo = () => ({ bar: 0 });
ESLint Docs on arrow-body
In your code sample it should be this way:
router.get('/', (req, res, next) => {
Product.find({})
.select('name price _id')
.then(items => {
const response = {
count: items.length,
products: items.map(item => ({ // no more errors
name: item.name,
price: item.price,
_id: item._id,
request: {
type: 'GET',
url: `http://localhost:3000/products/${item._id}`
});
})
};
res.status(200).json(response);
})
.catch(error => {
console.log(error);
res.status(500).json({ message: 'Server error' });
});
});
Since you're simply returning a plain object, there's no need for the extra pair of braces and return. Wrapping the object in parentheses ({ ... }), works as that is implicitly returned.

Try to omit return keyword and wrap the result into parenthesis:
products: items.map(item => ({
name: item.name,
price: item.price,
_id: item._id,
request: {
type: 'GET',
url: `http://localhost:3000/products/${item._id}`
}
}))