Node.js Tutorial

Building a Simple CRUD with Deta Base#

Setup#

Two dependencies are needed for this project, deta and express:

npm install deta express

To configure the app, import the dependencies and instantiate your database.

const express = require('express');
const { Deta } = require('deta');

const deta = Deta('myProjectKey'); // configure your Deta project
const db = deta.Base('simpleDB');  // access your DB


const app = express(); // instantiate express

app.use(express.json()) // for parsing application/json bodies

Creating Records#

For our database we are going to store records of users under a unique key. Users can have three properties:

{
    "name": "string",
    "age": number,
    "hometown": "string"
}

We'll expose a function that creates user records to HTTP POST requests on the route /users.

app.post('/users', async (req, res) => {
    const { name, age, hometown } = req.body;
    const toCreate = { name, age, hometown};
    const insertedUser = await db.put(toCreate); // put() will autogenerate a key for us
    res.status(201).json(insertedUser);
});

Request#

POST a payload to the endpoint:

{
    "name": "Beverly",
    "age": 44,
    "hometown": "Copernicus City"
}

Response#

Our server should respond with a status of 201 and a body of:

{
    "key": "dl9e6w6859a9",
    "name": "Beverly",
    "age": 44,
    "hometown": "Copernicus City"
}

Reading Records#

To read records, we can simply use Base.get(key).

If we tie a GET request to the /users path with a path param giving a user id (i.e. /users/dl9e6w6859a9), we can return a record of the user over HTTP.

app.get('/users/:id', async (req, res) => {
    const { id } = req.params;
    const user = await db.get(id);
    if (user) {
        res.json(user);
    } else {
        res.status(404).json({"message": "user not found"});
    }
});

Another option would to use Base.fetch(query) to search for records to return, like so:

app.get('/search-by-age/:age, async (req, res) => {
    const { age } = req.params;
    return (await db.fetch({'age': age}).next()).value;
});

Request#

Let's try reading the record we just created.

Make a GET to the path /users/dl9e6w6859a9.

Response#

The server should return the same record:

{
    "key": "dl9e6w6859a9",
    "name": "Beverly",
    "age": 44,
    "hometown": "Copernicus City"
}

Updating Records#

To update records under a given key, we can use Base.put(), which will replace the record under a given key.

We can tie a PUT request to the path /users/{id} to update a given user record over HTTP.

app.put('/users/:id', async (req, res) => {
    const { id } = req.params;
    const { name, age, hometown } = req.body;
    const toPut = { key: id, name, age, hometown };
    const newItem = await db.put(toPut);
    return res.json(newItem)
});

Request#

We can update the record by passing a PUT to the path /users/dl9e6w6859a9 with the following payload:

{
    "name": "Wesley",
    "age": 24,
    "hometown": "San Francisco"
}

Response#

Our server should respond with the new body of:

{
    "key": "dl9e6w6859a9",
    "name": "Wesley",
    "age": 24,
    "hometown": "San Francisco"
}

Deleting Records#

To delete records under a given key, we can use Base.delete(key), which will remove the record under a given key.

We can tie a DELETE request to the path /users/{id} to delete a given user record over HTTP.

app.delete('/users/:id', async (req, res) => {
    const { id } = req.params;
    await db.delete(id);
    res.json({"message": "deleted"})
});

Request#

We can delete the record by passing a DELETE to the path /users/dl9e6w6859a9.

{
    "name": "Wesley",
    "age": 24,
    "hometown": "San Francisco"
}

Response#

Our server should respond with:

{
    "message": "deleted"
}