Write data

  • 3 minutes

So far, you developed routes to read data for the Tailwind Traders products API. However, you need to add products too.

In this unit, we discuss the different methods we can use to add or update products and show examples of how that code is implemented. In the next unit, you'll actually edit your application code to add new products and update existing ones.

Understand how to write data to the API

To write data, use an HTTP method to indicate if the data is new or an update to existing data.

Common HTTP methods are:

Method Description
POST Create a new resource.
PUT Update an existing resource.
PATCH Update part of an existing resource.

PUT and PATCH are similar. The difference is that PUT replaces the entire resource. PATCH replaces only the properties that are specified in the request body.

Understand how to configure your app to receive data

To receive data in your web application, you configure Express based on the format of the incoming data such as HTML or JSON format. Converting and configuring data are common steps, regardless of the data format.

Note

Data is sent through the body of the request.

  1. Import a body parser. To convert the incoming data into a format that's readable, import the body-parser library that you installed with Express:

    let bodyParser = require('body-parser');

  2. Configure data type. Configure Express to parse the incoming body data into the intended format. The following code converts the data to JSON:

    app.use(bodyParser.json({ extended: false }));

The data sent from the client is available from req.body. You can read the data and insert it into the database.

Understand how to insert a new product

After configuring an app to receive data, you're ready to create code to insert data. Here's an example of some code that inserts new products to the Tailwind Trader's application data store:

// Insert a new product
app.post('/products', (req, res) => {
  const newProduct = req.body;
  newProduct.id = products.length + 1;
  products.push(newProduct);
  res.status(201).json(newProduct);
});

To insert a new product, call this API with a POST request to /products with a JSON body. For example:

{
  "name": "The Hobbit",
  "author": "J.R.R. Tolkien"
}

Understand how to update entire product

In addition to adding new products, Tailwind Traders needs the ability to replace existing product data. Here's a sample of that code, which handles PUT requests:

app.put('/products/:id', (req, res) => {
  const id = parseInt(req.params.id);
  const updatedProduct = req.body;
  const index = products.findIndex(product => product.id === id);
  if (index !== -1) {
    products[index] = updatedProduct;
    res.json(updatedProduct);
  } else {
    res.status(404).send('Product not found');
  }
});

To update a product, call this API with a PUT request to /products/:id with a JSON body. For example:

{
  "id": 1,
  "name": "The Hobbit",
  "author": "J.R.R. Tolkien"
}

Understand how to update part of a product

You also need the capability to replace a portion of a product's data rather than all of it. Here's an example of that code, which handles PATCH requests:

app.patch('/products/:id', (req, res) => {
  const id = parseInt(req.params.id);
  const updates = req.body;
  const index = products.findIndex(product => product.id === id);
  if (index !== -1) {
    // overwrite existing properties with updates
    products[index] = {...products[index], ...updates};
    res.json(products[index]);
  } else {
    res.status(404).send('Product not found');
  }
});

To update a specific portion of a product, call this API with a PATCH request to /products/:id with a JSON body. For example:

{
  "author": "J.R.R. Tolkien"
}