Spring boot PostMapping to Save a Object

Question

Im at the Beginning of learning Spring. I want to write a Backend which saves Recipes for a cookbook App. Therefore have This Model "Recipe":

@Document(collection = "recipes")
public class Recipe {

    @Id
    private String id;
    private final String recipeName;
    private final String recipeDescription;
    private final String difficulty;
    private ArrayList<Ingredient> ingredients;


    private Recipe(Builder builder) {
        this.recipeName = builder.recipeName;
        this.recipeDescription = builder.recipeDescription;
        this.difficulty = builder.difficulty;
        this.ingredients = builder.ingredients;

    }

    public static class Builder {
        private String recipeName;
        private String recipeDescription;
        private String difficulty;
        private ArrayList<Ingredient> ingredients;

        public Builder(String recipeName, String recipeDescription, String difficulty, ArrayList<Ingredient> ingredients){
            this.recipeName = recipeName;
            this.recipeDescription = recipeDescription;
            this.difficulty = difficulty;
            this.ingredients = ingredients;
        }
        public Recipe build() {
            return new Recipe(this);
        }
    }
// Getter and Setter... //

Its written with a Builder Pattern. Then i have This Controller, where i want to POST new Recipes:

@RestController
public class RecipeController {

    @Autowired
    RecipesRepository repo;


    @PostMapping("/postRecipe")
    public ResponseEntity postNewRecipe(@RequestBody Recipe r) {
        repo.save(r);
        return ResponseEntity.ok(r);
    }

}

If i send a Object to "/postRecipe" which looks exactly like the "Recipe"-Model im always getting a Error 500 though:

{
  "timestamp": "2020-08-18T15:40:49.664+00:00",
  "status": 500,
  "error": "Internal Server Error",
  "trace": "org.springframework.http.converter.HttpMessageConversionException: Type definition error: [simple type, class com.petziferum.rezeptbuch.models.Recipe]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `com.petziferum.rezeptbuch.models.Recipe` (no Creators, like default constructor, exist): cannot deserialize from Object value (no delegate- or property-based Creator)\n at [Source: (PushbackInputStream); line: 2, column: 3]\r\n\tat org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:242)\r\n\tat org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.read(AbstractJackson2HttpMessageConverter.java:227)\r\n\tat org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodArgumentResolver.readWithMessageConverters(AbstractMessageConverterMethodArgumentResolver.java:205)\r\n\tat org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.readWithMessageConverters(RequestResponseBodyMethodProcessor.java:158)\r\n\tat org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.resolveArgument(RequestResponseBodyMethodProcessor.java:131)\r\n\tat org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:121)\r\n\tat org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:167)\r\n\tat org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:134)\r\n\tat org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105)\r\n\tat org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:879)\r\n\tat org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793)\r\n\tat org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)\r\n\tat org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)\r\n\tat org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)\r\n\tat org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)\r\n\tat org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)\r\n\tat javax.servlet.http.HttpServlet.service(HttpServlet.java:660)\r\n\tat org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)\r\n\tat javax.servlet.http.HttpServlet.service(HttpServlet.java:741)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)\r\n\tat org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)\r\n\tat org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)\r\n\tat org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)\r\n\tat org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)\r\n\tat org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)\r\n\tat org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)\r\n\tat org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)\r\n\tat org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)\r\n\tat org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)\r\n\tat org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541)\r\n\tat org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)\r\n\tat org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)\r\n\tat org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)\r\n\tat org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)\r\n\tat org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:373)\r\n\tat org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)\r\n\tat org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)\r\n\tat org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1590)\r\n\tat org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)\r\n\tat java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)\r\n\tat java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)\r\n\tat org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)\r\n\tat java.base/java.lang.Thread.run(Thread.java:834)\r\nCaused by: com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `com.petziferum.rezeptbuch.models.Recipe` (no Creators, like default constructor, exist): cannot deserialize from Object value (no delegate- or property-based Creator)\n at [Source: (PushbackInputStream); line: 2, column: 3]\r\n\tat com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:67)\r\n\tat com.fasterxml.jackson.databind.DeserializationContext.reportBadDefinition(DeserializationContext.java:1611)\r\n\tat com.fasterxml.jackson.databind.DatabindContext.reportBadDefinition(DatabindContext.java:400)\r\n\tat com.fasterxml.jackson.databind.DeserializationContext.handleMissingInstantiator(DeserializationContext.java:1077)\r\n\tat com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromObjectUsingNonDefault(BeanDeserializerBase.java:1320)\r\n\tat com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:331)\r\n\tat com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:164)\r\n\tat com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4482)\r\n\tat com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3487)\r\n\tat org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:239)\r\n\t... 51 more\r\n",
  "message": "Type definition error: [simple type, class com.petziferum.rezeptbuch.models.Recipe]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `com.petziferum.rezeptbuch.models.Recipe` (no Creators, like default constructor, exist): cannot deserialize from Object value (no delegate- or property-based Creator)\n at [Source: (PushbackInputStream); line: 2, column: 3]",
  "path": "/postRecipe"
}

How am i able to save the Object correctly? Maybe Spring cant handle the Builder Pattern?

Answer 1

Spring don't use builder design pattern to create object. But a default constructor and get/setters are mandatory. Add the missing no-argument default constructor (as the error clearly says) and the setters in Recipe class. Also add @GenratedValue annotations on the Id attribute to generate dynamic Id in absence of Id value.

Answer 2

Addition to the answer provided by sachin,

I would recommend you to add Lombok to your project and add

@NoArgsConstructor @Getter @Setter

Annotations to the class.

So the code should look like

@NoArgsConstructor
@Getter
@Setter
Document(collection = "recipes") public class Recipe {

What does this do? Lombok is a library that reduces the amount of boilerplate code you need to write. Essentially you are instructing Lombok to write an empty constructor, all getters and all setter.

When JPA or any deserialisation happens, it creates an object with empty constructor, and then attach properties. This is done in order to initialize proxies that can handle lazy loads later on.

So if you want it to work, one available ways are using All args constructor, which is less recommended. Or NoArgsConstructor plus Getter and Setters.

Also, if you are keen on using builder, you can use @Builder along with @AllArgsConstructor from Lombok. But not for deserialization from database.