How to POST form-url-encoded data with Spring Cloud Feign

Question

Using spring-mvc annotations, how can I define an @FeignClient that can POST form-url-encoded?

Answer 1

Use form encoder for feign: https://github.com/OpenFeign/feign-form and your feign configuration can look like this:

class CoreFeignConfiguration {

  @Autowired
  private ObjectFactory<HttpMessageConverters> messageConverters

  @Bean
  @Primary
  @Scope(SCOPE_PROTOTYPE)
  Encoder feignFormEncoder() {
      new FormEncoder(new SpringEncoder(this.messageConverters))
  }
}

Then, the client can be mapped like this:

@FeignClient(name = 'client', url = 'localhost:9080', path ='/rest', configuration = CoreFeignConfiguration)
interface CoreClient {

    @RequestMapping(value = '/business', method = POST, consumes = MediaType.APPLICATION_FORM_URLENCODED)
    @Headers('Content-Type: application/x-www-form-urlencoded')
    void activate(Map<String, ?> formParams)
}

Answer 2

You must use FormEncoder in Feign encoder for url-form-encoded data in POST.

Include the dependency to your app:

Maven:

<dependency>
  <groupId>io.github.openfeign.form</groupId>
  <artifactId>feign-form</artifactId>
  <version>3.8.0</version>
</dependency>

Add FormEncoder to your Feign.Builder like so:

SomeFeign sample  = Feign.builder()
                      .encoder(new FormEncoder(new JacksonEncoder()))
                      .target(SomeFeign.class, "http://sample.test.org");

In the Feign interface

@RequestLine("POST /submit/form")
@Headers("Content-Type: application/x-www-form-urlencoded")
void from (@Param("field1") String field1, @Param("field2") String field2);

Ref for more info: https://github.com/OpenFeign/feign-form

Answer 3

Full Java code with a simplified version of kazuar solution, works with Spring Boot:

import java.util.Map;

import feign.codec.Encoder;
import feign.form.spring.SpringFormEncoder;

import org.springframework.beans.factory.ObjectFactory;
import org.springframework.boot.autoconfigure.http.HttpMessageConverters;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.cloud.openfeign.support.SpringEncoder;
import org.springframework.context.annotation.Bean;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;

import static org.springframework.http.MediaType.APPLICATION_FORM_URLENCODED_VALUE;

@FeignClient(name = "srv", url = "http://s.com", configuration = Client.Configuration.class)
public interface Client {

    @PostMapping(value = "/form", consumes = APPLICATION_FORM_URLENCODED_VALUE)
    void login(@RequestBody Map<String, ?> form);

    class Configuration {

        @Bean
        Encoder feignFormEncoder(ObjectFactory<HttpMessageConverters> converters) {
            return new SpringFormEncoder(new SpringEncoder(converters));
        }
    }
}

Dependency:

<dependency>
   <groupId>org.springframework.cloud</groupId>
   <artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>