[Solved] Cannot deserialize instance of enum list spring boot exception

Cannot deserialize instance of enum list spring boot exception

Issue

When you are trying to map the POST request body with enum properties, then you must need to do @JsonCreator to map the enums with request body and the list of properties available in the enum.

Full Exception for reference

JSON parse error: Cannot deserialize instance of ‘com.ngdeveloper.posts.enums.PostType’ out of START_OBJECT token; nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of ‘com.ngdeveloper.posts.enums.PostType’ out of START_OBJECT token at [Source: (PushbackInputStream); line 17, column 5] (through reference chain: com.ngdeveloper.dto.posts”

Solution

Issue code for reference

@Getter
@JsonFormat(shape = JsonFormat.Shape.OBJECT)
public enum PostType {
   NEW("NEW","New Post"),
   DRAFT("DRAFT", "Drafted Post");

 private String type;
 private String description;
  
  PostType(String type, String description){
     this.type = type;
     this.description = description;
  }
 
}

Fixed code for reference

Add the @JsonCreator annotation with the static method to map the json property with the enums.

@Getter
@JsonFormat(shape = JsonFormat.Shape.OBJECT)
public enum PostType {
   NEW("NEW","New Post"),
   DRAFT("DRAFT", "Drafted Post");

 private String type;
 private String description;
  
  PostType(String type, String description){
     this.type = type;
     this.description = description;
  }

   @JsonCreator
   static PostType findValue(@JsonProperty("type") String type, @JsonProperty("description") String description){
      return Arrays.stream(PostType.values()).filter(pt -> pt.type.equlas(type) && pt.description.equals(description)).findFirst().get();
}
 
}

Still “Cannot deserialize instance of enum list spring boot exception” comes ?

• Then you may need compare the exact value of the enums are matching with the request body.
• Do maven build and try once again!