7.2 Declarative HTTP Clients with @Client - 7.2.1 Customizing Parameter Binding - 《Micronaut v1.3.7 Documentation》

7.2.1 Customizing Parameter Binding
- Type Based Binding Parameters

7.2.1 Customizing Parameter Binding

The previous example presented a trivial example that uses the parameters of a method to represent the body of a POST request:

PetOperations.java

@Post
Single<Pet> save(@NotBlank String name, @Min(1L) int age);

The save method when called will perform an HTTP POST with the following JSON by default:

Example Produced JSON

{"name":"Dino", "age":10}

You may however want to customize what is sent as the body, the parameters, URI variables and so on. The @Client annotation is very flexible in this regard and supports the same HTTP Annotations as Micronaut’s HTTP server.

For example, the following defines a URI template and the name parameter is used as part of the URI template, whilst @Body is used declare that the contents to send to the server are represented by the Pet POJO:

PetOperations.java

@Post("/{name}")
Single<Pet> save(
    @NotBlank String name, (1)
    @Body @Valid Pet pet) (2)

1	The name parameter, included as part of the URI, and declared `@NotBlank`
2	The `pet` parameter, used to encode the body and declared `@Valid`

The following table summarizes the parameter annotations, their purpose, and provides an example:

Table 1. Parameter Binding Annotations
Annotation	Description	Example
@Body	Allows to specify the parameter that is the body of the request	`@Body String body`
@CookieValue	Allows specifying parameters that should be sent as cookies	`@CookieValue String myCookie`
@Header	Allows specifying parameters that should be sent as HTTP headers	`@Header String contentType`
@QueryValue	Allows customizing the name of the URI parameter to bind from	`@QueryValue(“userAge”) Integer age`
@PathVariable	Used to bind a parameter exclusively from a Path Variable.	`@PathVariable Long id`
@RequestAttribute	Allows specifying parameters that should be set as request attributes	`@RequestAttribute Integer locationId`

Type Based Binding Parameters

Some parameters are recognized by their type instead of their annotation. The following table summarizes the parameter types, their purpose, and provides an example:

Type	Description	Example
BasicAuth	Allows binding of basic authorization credentials	`BasicAuth basicAuth`