Trying to use Spring Boot REST to Read JSON String from POST

Question

Am using the latest version of Spring Boot to read in a sample JSON via Restful Web Service...

Here's my pom.xml:

<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0"                 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0           http://maven.apache.org/maven-v4_0_0.xsd"          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">      <modelVersion>4.0.0</modelVersion>      <groupId>org.springframework</groupId>     <artifactId>myservice</artifactId>     <version>0.1.0</version>      <parent>         <groupId>org.springframework.boot</groupId>         <artifactId>spring-boot-starter-parent</artifactId>         <version>1.2.2.RELEASE</version>     </parent>      <properties>         <java.version>1.7</java.version>         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>     </properties>      <dependencies>         <dependency>             <groupId>org.springframework.boot</groupId>             <artifactId>spring-boot-starter-web</artifactId>         </dependency>         <dependency>             <groupId>org.springframework.boot</groupId>             <artifactId>spring-boot-starter-test</artifactId>             <scope>test</scope>         </dependency>         <dependency>             <groupId>org.springframework.data</groupId>             <artifactId>spring-data-rest-webmvc</artifactId>         </dependency>         <dependency>     </dependencies>      <build>         <plugins>             <plugin>                 <groupId>org.springframework.boot</groupId>                 <artifactId>spring-boot-maven-plugin</artifactId>             </plugin>         </plugins>     </build>      <repositories>         <repository>             <id>spring-releases</id>             <name>Spring Releases</name>             <url>https://repo.spring.io/libs-release</url>         </repository>         <repository>             <id>org.jboss.repository.releases</id>             <name>JBoss Maven Release Repository</name>             <url>https://repository.jboss.org/nexus/content/repositories/releases</url>         </repository>     </repositories>      <pluginRepositories>         <pluginRepository>             <id>spring-releases</id>             <name>Spring Releases</name>             <url>https://repo.spring.io/libs-release</url>         </pluginRepository>     </pluginRepositories>  </project> 

Here's my web service code:

import org.springframework.web.bind.annotation.RequestBody; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import org.springframework.web.bind.annotation.RestController;  @RestController @RequestMapping("/myservice") public class BaseService {        @RequestMapping(value="/process", method = RequestMethod.POST)     public void process(@RequestBody String payload) throws Exception {         System.out.println(payload);     } } 

When I invoke it using the following command:

curl -H "Accept: application/json" -H "Content-type: application/json"  -X POST -d '{"name":"value"}' http://localhost:8080/myservice/process 

I get this error message:

{"timestamp":1427515733546,"status":400,  "error":"Bad Request",  "exception": "org.springframework.http.converter.HttpMessageNotReadableException","  message":  "Could not read JSON: Can not deserialize instance of java.lang.String   out of START_OBJECT token\n at    [Source: java.io.PushbackInputStream@8252f; line: 1, column: 1];    nested    exception is com.fasterxml.jackson.databind.JsonMappingException:   Can not deserialize instance of java.lang.String out of START_OBJECT token\n       at [Source: java.io.PushbackInputStream@8252f; line: 1, column: 1]",   "path":"/myservice/process" 

The only thing I am trying to do is pass in some valid JSON (as a string via curl) and to see if the String payload enters the process method as {"name":"value"}

What am I possibly doing wrong?

Thank you for taking the time to read this...

Answer 1

I think the simplest/handy way to consuming JSON is using a Java class that resembles your JSON: https://stackoverflow.com/a/6019761

But if you can't use a Java class you can use one of these two solutions.

Solution 1: you can do it receiving a Map<String, Object> from your controller:

@RequestMapping(     value = "/process",      method = RequestMethod.POST) public void process(@RequestBody Map<String, Object> payload)      throws Exception {    System.out.println(payload);  } 

Using your request:

curl -H "Accept: application/json" -H "Content-type: application/json" \ -X POST -d '{"name":"value"}' http://localhost:8080/myservice/process 

---

Solution 2: otherwise you can get the POST payload as a String:

@RequestMapping(     value = "/process",      method = RequestMethod.POST,     consumes = "text/plain") public void process(@RequestBody String payload) throws Exception {    System.out.println(payload);  } 

Then parse the string as you want. Note that must be specified consumes = "text/plain" on your controller. In this case you must change your request with Content-type: text/plain:

curl -H "Accept: application/json" -H "Content-type: text/plain" -X POST \ -d '{"name":"value"}' http://localhost:8080/myservice/process