As I've experienced one of the most commonly asked question for a software enigneer position is about HTTP methods, doesn't matter if you are applying for frontend or backend position, both sides should understand the differences and use these methods properly while either building or consuming an API.

So here are the five most commonly used HTTP methods and what you should know about them!

GET 🔎

GET is used for retrieving multiple resources or retrieving a single resource.

Examples

List of resource

/api/user

Would return a list of user resource. Here in our context a resource is a single row in a database.

You can build pagination and simple search functionality with query strings:

/api/user?page=1&pageSize=5&hasProfilePicture=true

Single resource

/api/user/1337

Would return a single user resource which has an id of 1337.

POST 📬

POST is used for creating new resources. Each request shall create a new resource.

Example

For example to create a new user we could do:

/api/user

With the body of:

{
  username: "great username",
  password: "super-safe-password"
}

Of course in this case the password needs to be hashed.

PUT ♻️

PUT is used for replace resource with the sent one. It can be also used to create new resource, but by RFC it should only replace resource and not create new one.

Example

/api/map/1337

With the body of:

{
  lat: 42.42,
  lng: 42.42
}

This would completely replace the resource with the id of 1337 with the new - sent - data.

PATCH 🩹

PATCH is used for replace some part of the original resource. Should be used as partial updates.

Example

/api/map/1337

With the body of:

{
  lat: 42.42
}

The difference between PUT and PATCH is that PUT replaces the whole resource with the sent one while PATCH only changes what is sent.

DELETE 🗑️

DELETE is used for deleting a resource.

Example

DELETE /api/map/1337

Would delete map with the id of 1337 if exist.

Bonus question ➕

Which are idempotents and what is idempotent?

Idempotent means that multiple requests can be made with the server state unaffected. In other words idempotent requests should NOT have any side effect, it shouldn't change the server state.

In this sense only POST is NOT idempotent, since POST is creating new "database rows" on every request.

Closing thoughts

Thanks for reading. Please do keep in mind that technically there are no restrictions for creating these APIs so you can customize each and every behaviour.

Thank you for reading, and let's connect!

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