Express JS #6 - PUT Requests

Summary

This script explains the differences between key HTTP request methods: PUT, PATCH, and DELETE, commonly used in APIs. PUT updates the entire resource, requiring all fields to be included in the request, while PATCH allows partial updates, modifying only the specified fields. DELETE, on the other hand, is used to remove records. The speaker demonstrates how to implement a PUT request to update user information, with examples of handling missing fields and invalid data, and explains the importance of understanding these methods when building APIs.

Takeaways

• 🔧 PUT and PATCH requests are both used to update data, but differ in how they handle updates.
• ✂️ A PATCH request updates only part of a resource, such as changing just the username without touching other fields like display name.
• 📦 A PUT request updates the entire resource, meaning all fields must be included, even those that aren’t being changed.
• 💡 If a PUT request omits fields from the request body, those fields will be removed or set to null in the database.
• ❌ DELETE requests are used to remove resources like users or products from the database.
• 🆔 For PUT requests, fields like ID should not be modified, especially when auto-generated by the database.
• 🚫 If a PUT request is sent with an invalid ID, a '400 Bad Request' response is returned.
• 🔍 When searching for a user by ID, if the user isn’t found, the response will return '404 Not Found'.
• 🔄 PATCH requests are more flexible since they only require you to send the fields you want to update, avoiding the need to send the full object.
• 👍 PUT requests should always ensure that unchanged fields are still included to avoid accidental data loss.

Q & A

What are the five HTTP request methods mentioned in the script?

The five HTTP request methods mentioned are GET, POST, PUT, PATCH, and DELETE.

What is the primary difference between a PUT request and a PATCH request?

A PUT request updates the entire resource, meaning all fields must be included in the request, even if they are not being modified. A PATCH request, on the other hand, allows for a partial update, meaning only the fields being modified need to be included.

What happens if you omit a field in a PUT request?

If you omit a field in a PUT request, that field will be removed or set to null in the updated resource. This is because PUT replaces the entire resource with the provided data.

When would you use a DELETE request?

A DELETE request is used to remove a resource from the database, such as deleting a user, product, or order.

What happens if you provide an invalid ID in a PUT request?

If an invalid ID is provided in a PUT request, the server will return a 400 Bad Request status indicating that the request was not valid.

What status code is returned when a requested user is not found using the PUT method?

If the user is not found using the PUT method, the server returns a 404 Not Found status.

How does Express handle routes with different HTTP methods?

Express allows the same route path to be used with different HTTP methods (e.g., GET, PUT, POST) without conflicts, as the method itself determines how the request is processed.

Why should you be cautious when using a PUT request to update resources?

You need to be cautious because PUT updates the entire resource. If you omit fields that should remain unchanged, they might be removed or set to null, potentially causing data loss.

How is the user ID preserved during a PUT request update?

The user ID is preserved by explicitly setting the ID field in the updated object, as the ID is often auto-generated and should not be modified.

What is the purpose of checking if `findUserIndex` is -1 during a PUT request?

Checking if `findUserIndex` is -1 ensures that the user exists before attempting to update it. If `findUserIndex` is -1, it means the user was not found, and a 404 status is returned.