No Creators like default construct exist cannot deserialize from Object value no delegate- or property-based Creator

Question

I am trying to consume an API using Retrofit and Jackson to deserialize  I am getting the onFailure error No Creators  like default construct  exist   cannot deserialize from Object value  no delegate- or property-based Creator

User · Answer

You need to use jackson-module-kotlin to deserialize to data classes   See here for details   The error message above is what Jackson gives you if you try to deserialize some value into a data class when that module isn t enabled or  even if it is  when the ObjectMapper it uses doesn t have the KotlinModule registered   For example  take this code   data class TestDataClass  val foo  String   val jsonString         foo    bar       val deserializedValue   ObjectMapper   readerFor TestDataClass  class java  readValue lt TestDataClass gt  jsonString    This will fail with the following error   com fasterxml jackson databind exc MismatchedInputException  Cannot construct instance of  test SerializationTests TestDataClass   although at least one Creator exists   cannot deserialize from Object value  no delegate- or property-based Creator    If you change the code above and replace ObjectMapper with jacksonObjectMapper  which simply returns a normal ObjectMapper with the KotlinModule registered   it works   i e   val deserializedValue   jacksonObjectMapper   readerFor TestDataClass  class java  readValue lt TestDataClass gt  jsonString    I m not sure about the Android side of things  but it looks like you ll need to get the system to use the jacksonObjectMapper to do the deserialization

User · Answer

Sorry for being lazy just providing solution without explaining the reason  Now I m updating my answer  Reason  This error occurs because jackson library doesn t know how to create your model which doesn t have empty constructor and the model contains constructor with parameters which didn t annotated its parameters with  JsonProperty  quot field name quot    By default java compiler creates empty constructor if you didn t add constructor to your class  Solution  Add empty constructor to your model or annotate constructor parameters with  JsonProperty  quot field name quot   If you use kotlin data class then also can annotate with  JsonProperty  quot field name quot   or register jackson module kotlin to ObjectMapper  You can create your models using http   www jsonschema2pojo org

User · Answer

If you re using Lombok on a POJO model  make sure you have these annotations    Getter  Builder  NoArgsConstructor  AllArgsConstructor   It could vary  but make sure  Getter and especially  NoArgsConstructor

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My cause of issue seems very uncommon to me  not sure if anybody else gets the error under same condition  I found the cause by diffing previous commits  here you go   Via my build gradle I was using these 2 compiler options  and commenting out this line fixed the issue   compileJava options compilerArgs     -Xlint unchecked   -Xlint deprecation

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I had this issue and i fixed with the code below   Configuration open class JacksonMapper         Bean     open fun mapper    ObjectMapper           val mapper   ObjectMapper                        mapper registerModule KotlinModule            return mapper

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I could resolve this problem in Kotlin with help of  JacksonProperty annotation  Usage example for above case would be   import com fasterxml jackson annotation JsonProperty     data class Station        JacksonProperty  repsol id   val repsol id  String        JacksonProperty  name   val name  String

User · Answer

If you are using LOMBOK  Create a file lombok config if you don t have one and add this line  lombok anyconstructor addconstructorproperties true

User · Answer

I had a similar issue  using Jackson  lombok  gradle  and a POJO without no args constructor - the solution was to add   lombok anyConstructor addConstructorProperties true   to the lombok config file

User · Answer

I got here searching for this error   No Creators  like default construct  exist   cannot deserialize from Object value  no delegate- or property-based Creator   Nothing to do with Retrofit but if you are using Jackson this error got solved by adding a default constructor to the class throwing the error  More here  https   www baeldung com jackson-exception

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I solved this issue by adding a no argument constractor  If you are using Lombok  you only need to add  NoArgsConstructor annotation   AllArgsConstructor  NoArgsConstructor  Getter  ToString  EqualsAndHashCode public class User       private Long userId      private String shortName

User · Answer

I m using rescu with Kotlin and resolved it by using  ConstructorProperties      data class MyResponse  ConstructorProperties  message    count   constructor          val message  String          val count  Int         Jackson uses  ConstructorProperties  This should fix Lombok  Data as well

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I know this is an old post  but for anyone using Retrofit  this can be useful useful   If you are using Retrofit   Jackson   Kotlin   Data classes  you need     add implement group   com fasterxml jackson module   name   jackson-module-kotlin   version   2 7 1-2  to your dependencies  so that Jackson can de-serialize into Data classes When building retrofit  pass the Kotlin Jackson Mapper  so that Retrofit uses the correct mapper  ex        val jsonMapper   com fasterxml jackson module kotlin jacksonObjectMapper        val retrofit   Retrofit Builder                            addConverterFactory JacksonConverterFactory create jsonMapper              build     Note  If Retrofit is not being used   Jayson Minard has a more general approach answer

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When you are using Lombok builder you will get the above error      JsonDeserialize builder   StationResponse StationResponseBuilder class   public class StationResponse       define required properties             JsonIgnoreProperties ignoreUnknown   true    JsonPOJOBuilder withPrefix        public static class StationResponseBuilder      Reference   https   projectlombok org features Builder With Jackson

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Extending Yoni Gibbs s answer  if you are in an android project using retrofit and configure serialization with Jackson you can do these things in order to deserialization works as expected with kotlin s data class   In your build gradle import   implementation  com fasterxml jackson module jackson-module-kotlin 2 11      Then  your implementation of retrofit   val serverURL    http   localhost 8080 api v1   val objectMapper   ObjectMapper   objectMapper registerModule KotlinModule      Only if you are using Java 8 s Time API too  require jackson-datatype-jsr310 objectMapper registerModule JavaTimeModule     Retrofit Builder        baseUrl serverURL       client          OkHttpClient Builder               readTimeout 1  TimeUnit MINUTES   No mandatory              connectTimeout 1  TimeUnit MINUTES   No mandatory              addInterceptor UnauthorizedHandler     No mandatory              build         addConverterFactory                  JacksonConverterFactory create objectMapper                     addCallAdapterFactory RxJava2CallAdapterFactory create         build     Data class    JsonIgnoreProperties ignoreUnknown   true  data class Task val id  Int                  val name  String                   JsonSerialize using   LocalDateTimeSerializer  class                   JsonDeserialize using   LocalDateTimeDeserializer  class                  val specificDate  LocalDateTime                   var completed  Boolean                  val archived  Boolean                  val taskListId  UUID

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Just want to point out that this answer provides a better explanation  Basically you can either have  Getter and  NoArgConstructor together or let Lombok regenerates  ConstructorProperties using lombok config file  or compile your java project with -parameters flags  or let Jackson use Lombok s  Builder

User · Answer

As the error mentioned the class does not have a default constructor   Adding  NoArgsConstructor to the entity class should fix it

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If you are using Unirest as the http library  using the GsonObjectMapper instead of the JacksonObjectMapper will also work    lt  -- https   mvnrepository com artifact com konghq unirest-object-mappers-gson -- gt   lt dependency gt       lt groupId gt com konghq lt  groupId gt       lt artifactId gt unirest-object-mappers-gson lt  artifactId gt       lt version gt 2 3 17 lt  version gt   lt  dependency gt    Unirest config   objectMapper   GsonObjectMapper

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Encountered the same error in below Usecase  I tried to hit the Rest Put mapping  end point using sprint boot 2 0 0 Snapshot Version  without having default constructor in respective bean  But with latest Spring Boot versions 2 4 1 Version  the same piece of code is working without error  so the bean default constructor is no longer needed in latest version of Spring Boot

[android] No Creators, like default construct, exist): cannot deserialize from Object value (no delegate- or property-based Creator

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