How to Use OpenFeign 4.1.2: Parameter Constraints & Custom Status Codes

Environment

SpringBoot 3.3.1 + Spring Cloud 2023.0.2

1. Introduction

OpenFeign is a declarative HTTP client in Spring Cloud that simplifies remote service calls. The latest version 4.1.2 adds two previously unsupported features: request parameter condition limiting and custom status codes.

2. Practical Examples

2.1 Request Parameter Constraints

Remote interface

<code>@GetMapping(value = "/params/user", params = "action=query")
public String queryUser() {
    return "query user";
}
</code>

The params attribute forces the request to contain action=query ; otherwise an error occurs.

Feign client declaration

<code>@FeignClient(name = "param", url = "http://localhost:8080")
public interface ParamFeign {
    @GetMapping(value = "/params/user", params = "action=query")
    String queryUser();
}
</code>

Note: the Feign method must match the remote interface exactly.

Calling this Feign client with OpenFeign 4.1.1 results in the error "request does not contain action=query" . Upgrading Spring Cloud to version 2023.0.2 (which uses OpenFeign 4.1.2) resolves the issue.

<code>&lt;spring-cloud.version&gt;2023.0.2&lt;/spring-cloud.version&gt;
</code>

2.2 Custom Status Codes

Remote interface

<code>@RestController
public class ParamController {
    @GetMapping("/api/status")
    public ResponseEntity<String> status() {
        return ResponseEntity.status(289).body("Custom 289 - status code");
    }
}
</code>

Status 289 is not defined in the HTTP standard (only 2xx codes are defined). The service responds correctly, but OpenFeign 4.1.1 treats it as an error.

Feign client declaration (still 4.1.1)

<code>@FeignClient(name = "param", url = "http://localhost:8080")
public interface ParamFeign {
    @GetMapping("/api/status")
    ResponseEntity<String> status();
}
</code>

Calling the Feign method returns an error because the status code is not recognized.

After upgrading to OpenFeign 4.1.2, custom status codes are supported, but only within the 200‑300 range. Example with status 333:

<code>@GetMapping("/api/status")
public ResponseEntity<String> status() {
    return ResponseEntity.status(333).body("Custom 333 - status code");
}
</code>

Calling this endpoint works via Postman, but Feign throws an exception because the internal rule evaluates status > 300 as false.

Conclusion

OpenFeign 4.1.2 introduces request parameter constraints and support for custom status codes (limited to 200‑300). Upgrading Spring Cloud to version 2023.0.2 is required to use these features.