An endpoint is represented as a value of type
Endpoint[I, E, O, S], where:
Iis the type of the input parameters
Eis the type of the error-output parameters
Ois the type of the output parameters
Sis the type of streams that are used by the endpoint’s inputs/outputs
Input/output parameters (
O) can be:
- of type
Unit, when there’s no input/ouput of the given type
- a single type
- a tuple of types
Hence, an empty, initial endpoint (
tapir.endpoint), with no inputs and no outputs, from which all other endpoints are
derived has the type:
import sttp.tapir._ val endpoint: Endpoint[Unit, Unit, Unit, Any] = ???
An endpoint which accepts two parameters of types
Int, upon error returns a
String, and on normal
completion returns a
User, would have the type:
import sttp.tapir._ val userEndpoint: Endpoint[(UUID, Int), String, User, Any] = ???
You can think of an endpoint as a function, which takes input parameters of type
I and returns a result of type
Either[E, O], where inputs or outputs can contain streaming bodies of type
Note that the empty
endpoint description maps no values to either error and success outputs, however errors
are still represented and allowed to occur. If you would prefer to use an endpoint description, where
errors can not happen, use
infallibleEndpoint: Endpoint[Unit, Nothing, Unit, Nothing]. This might be useful when
interpreting endpoints as a client.
Defining an endpoint¶
The description of an endpoint is an immutable case class, which includes a number of methods:
description, etc. methods allow modifying the endpoint information, which will then be included in the endpoint documentation
postetc. methods specify the HTTP method which the endpoint should support
outmethods allow adding a new input/output parameter
mapInTo, … methods allow mapping the current input/output parameters to another value or to a case class
An important note on mapping: in tapir, all mappings are bi-directional. That’s because each mapping can be used to generate a server or a client, as well as in many cases can be used both for input and for output.
Read on about describing endpoint inputs/outputs.