Node, Express, MongoDB: Creating a schema with an array of objects?

Question

Here's my desired schema:

{
    username: "taimoor",
    pairs: [
        {
            code: "CA",
            site: "google.ca"
        },
        {
            code: "US",
            site: "google.com"
        },
        {
            code: "GB",
            site: "google.co.uk"
        }
    ]
    date: 1574880349,
}

Here's my current schema:

const redirectionSchema = new mongoose.Schema({
    username: {
        type: String,
        required: true,
    },
    pairs: [
        // What do I place here?
    ],
    date: {
        type: Date,
        required: true,
        default: Date.now
    }
})

I don't know how to proceed and implement this using mongoose. Should I create another schema called Pair? And if so:

How do I ensure the pairs will be valid?
How do I add a Pair to "pairs" programmatically?

Thanks for your time, this is my first time using NoSQL.

Hi, did you check my answer? If so, please give some feedback whether it worked or not. — SuleymanSah
– SuleymanSah, Commented Nov 27, 2019 at 20:54

SuleymanSah · Accepted Answer · 2019-11-27 19:42:53Z

You need to have an inner schema for pairs. This way you can apply required or other validations to the pairs.

const mongoose = require("mongoose");

const redirectionSchema = new mongoose.Schema({
  username: {
    type: String,
    required: true
  },
  pairs: [
    new mongoose.Schema({
      code: {
        type: String,
        required: true
      },
      site: {
        type: String,
        required: true
      }
    })
  ],
  date: {
    type: Date,
    required: true,
    default: Date.now
  }
});

module.exports = mongoose.model("Redirect", redirectionSchema);

And you can use the following App.js to create a document with username and pairs, or add another pair to an existing document.

App.js

const express = require("express");
const app = express();
const mongoose = require("mongoose");
const Redirect = require("./models/redirect");
const url = "mongodb://localhost:27017/redirectDB";

const port = process.env.PORT || 3000;

app.use(express.json());

mongoose
  .connect(url, {
    useNewUrlParser: true,
    useUnifiedTopology: true
  })
  .then(() => {
    app.listen(port, () => {
      console.log(`App running on port ${port}...`);
    });
  })
  .catch(error => console.log(error));

app.post("/redirect", async (req, res) => {
  try {
    const result = await Redirect.create(req.body);
    res.send(result);
  } catch (err) {
    console.log(err);
    res.status(500).send("Something went wrong");
  }
});

app.post("/redirect/:id/pair", async (req, res) => {
  const { code, site } = req.body;

  try {
    const result = await Redirect.findByIdAndUpdate(
      req.params.id,
      {
        $push: {
          pairs: { code, site }
        }
      },
      { new: true }
    );

    res.send(result);
  } catch (err) {
    console.log(err);
    res.status(500).send("Something went wrong");
  }
});

To create username and pairs send a post requrest to the url http://localhost:3000/redirect like this:

{
    "username": "taimoor",
    "pairs": [
        {
            "code": "CA",
            "site": "google.ca"
        },
        {
            "code": "US",
            "site": "google.com"
        }
    ]
}

The response will be like this:

{
    "_id": "5ddecfcb3cd5c035b4c31d95",
    "username": "taimoor",
    "pairs": [
        {
            "_id": "5ddecfcb3cd5c035b4c31d97",
            "code": "CA",
            "site": "google.ca"
        },
        {
            "_id": "5ddecfcb3cd5c035b4c31d96",
            "code": "US",
            "site": "google.com"
        }
    ],
    "date": "2019-11-27T19:34:35.781Z",
    "__v": 0
}

And later we can add a new pair to this document using a post request to this url http://localhost:3000/redirect/5ddecfcb3cd5c035b4c31d95/pair. The id in the url is the id we previosuly created, and got in the response.

Request:

{
    "code": "GB",
    "site": "google.co.uk"
}

Response:

{
    "_id": "5ddecfcb3cd5c035b4c31d95",
    "username": "taimoor",
    "pairs": [
        {
            "_id": "5ddecfcb3cd5c035b4c31d97",
            "code": "CA",
            "site": "google.ca"
        },
        {
            "_id": "5ddecfcb3cd5c035b4c31d96",
            "code": "US",
            "site": "google.com"
        },
        {
            "_id": "5dded01693be502168a0f794",
            "code": "GB",
            "site": "google.co.uk"
        }
    ],
    "date": "2019-11-27T19:34:35.781Z",
    "__v": 0
}

Thanks very much. $push works for me. Any idea how I can make the code value of every pair unique? I'm trying to fix that problem now and it's surprisingly difficult
@TaimoorAhmad I will look at tomorrow, but maybe you can ask another new question so that others also can reply.

Miguel Medellín · Accepted Answer · 2019-11-27 19:23:45Z

1

Model

const redirectionSchema = new mongoose.Schema({
    username: {
        type: String,
        required: true,
    },
    pairs: [
        {
            _id: false,
            code: { type: String },
            site: { type: String }
        }
    ],
    date: {
        type: Date,
        required: true,
        default: Date.now
    }
})

const Redirection = mongoose.model('Redirection', redirectionSchema);

Use

const redirection = new Redirection({
    username: "taimoor",
    pairs: [
        {
            code: "CA",
            site: "google.ca"
        },
        {
            code: "US",
            site: "google.com"
        },
        {
            code: "GB",
            site: "google.co.uk"
        }
    ],
    date: new Date(1574880349),
})

redirection.save();

Example database output

{
  "_id": {
    "$oid": "5ddecc4c6dd3760c40ff354b"
  },
  "username": "taimoor",
  "pairs": [
    {
      "code": "CA",
      "site": "google.ca"
    },
    {
      "code": "US",
      "site": "google.com"
    },
    {
      "code": "GB",
      "site": "google.co.uk"
    }
  ],
  "date": {
    "$date": "1970-01-19T05:28:00.349Z"
  },
  "__v": 0
}

edited Nov 27, 2019 at 19:23

answered Nov 27, 2019 at 18:56

Miguel Medellín

114 bronze badges

3 Comments

Maruta Over a year ago

remember to add a question ;)

Taimoor Ahmad Over a year ago

Thank you. Why is the _id of the pair set to false? Since it's not a schema wouldn't that have no effect?

Miguel Medellín Over a year ago

Setting _id to false is optional, I do it when an element is added to the array does not generate a new _id, it depends on the scenario, general does not have much use.

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