RESTful API required parameters in query string?
rest
Solution
When designing a RESTful API, what to do if a GET request only makes sense if there are specific parameters associated with the request? Should the parameters be passed as a query string, and if so, what to do when all the parameters aren't specified or are formatted incorrectly?
By REST your API must fulfill the REST constraints, which are described in the Fielding dissertation. One of these constraints is the uniform interface constraint, which includes the HATEOAS constraint. According to the HATEOAS constraint your API must serve a standard hypermedia format as response. This hypermedia contains hyperlinks (e.g. HTML links, forms) annotated with metadata (e.g. link relation or RDF annotation). The clients check the metadata, which explains to them what the hyperlink does. After that they can decide whether they want to follow the link or not. When they follow the link, they can build the HTTP request based on the URI template, parameters, etc... and send it to the REST service.
In your case it does not matter which URI structure you use, it is for service usage only, since the client always uses the given URI template and the client does not care what is in that template until it is a valid URI template which it can fill with parameters.
In most of the cases your client has enough validation information to test whether the params are incorrect or missing. In that case it does not send a HTTP request, so you have nothing to do in the service. If an invalid param gets through, then in your case your service sends back a 404 - not found, since the URI is the resource identifier, and no resource belongs to an invalid URI (generated from the given URI template and invalid params).
Problem
When designing a RESTful API, what to do if a GET request only makes sense if there are specific parameters associated with the request? Should the parameters be passed as a query string, and if so, what to do when all the parameters aren't specified or are formatted incorrectly? For example, lets say i have a Post resource, which can be accessed by `api/posts` endpoint. Each post has a geographical location, and posts can be retrieved ONLY when specifying an area that the posts may reside in. Thus, 3 parameters are required: latitude, longitude and radius. I can think of 2 options in this case: 1. Putting the parameters in query string: `api/posts/?lat=5.54158&lng=71.5486&radius=10` 2. Putting the parameters in the URL: `api/posts/lat/5.54158/lng/71.5486/radius/10` Which of these would be the correct approach? It seems wrong to put required parameters in the query string, but the latter approach feels somewhat 'uglier'. PS. I'm aware there are many discussion on this topic already (for example: REST API Best practices: Where to put parameters?), but my question is specifically addressed to the case when parameters are required, not optional.