When to use Path vs Query Parameters?Solved

That is a very common point of confusion when you first start working with APIs. In proper REST API design, there is a strict rule for when to use each, even though some developers do not always follow it perfectly. 

A path variable is used to identify one specific, unique item. Think of it like a file path on your computer. If you want to pull a specific user profile, /api/users/12345 is the correct approach because that ID points to one exact destination. 

A query parameter, on the other hand, is used to filter, sort, or search through a broader list of items. If you want to find all users in the sales department, you would use /api/users?department=sales. Simply put, use the path to locate a specific noun, and use the query to filter a list of nouns. 

To add a practical tip to what Morgan explained, understanding this difference will really help you handle errors when you write your scripts. 

If your script uses a path variable and the ID does not exist, the server will almost always throw a 404 Not Found error because that specific destination is missing. However, if you use a query parameter to search for a user and they do not exist, the server usually returns a 200 OK status with an empty list. The server is essentially saying the search function worked perfectly, but it found zero matches for your filter. Knowing how the API interprets these URLs dictates exactly how you need to write your error handling.