No Creators, like default construct, exist): cannot deserialize from Object value (no delegate- or property-based Creator
AndroidKotlinJacksonRetrofit2Android Problem Overview
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
.
Android Solutions
Solution 1 - Android
Reason: This error occurs because jackson library doesn't know how to create your model which doesn't have an empty constructor and the model contains constructor with parameters which didn't annotated its parameters with @JsonProperty("field_name")
. By default java compiler creates empty constructor if you didn't add constructor to your class.
Solution:
Add an empty constructor to your model or annotate constructor parameters with @JsonProperty("field_name")
If you use a Kotlin data class then also can annotate with @JsonProperty("field_name")
or register jackson module kotlin to ObjectMapper
.
You can create your models using http://www.jsonschema2pojo.org/.
Solution 2 - Android
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
Solution 3 - Android
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<TestDataClass>(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<TestDataClass>(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.
Solution 4 - Android
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
.
Solution 5 - Android
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.
Solution 6 - Android
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
Solution 7 - Android
I am using Quarkus, Jackson and Lombok. So I solved this issue by adding @Jacksonized
attribute on model class.
So all attributes are:
@Jacksonized //missing
@Builder
@Data
@NoArgsConstructor
@AllArgsConstructor
public class ...
Solution 8 - Android
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;
}
Solution 9 - Android
As the error mentioned the class does not have a default constructor.
Adding @NoArgsConstructor to the entity class should fix it.
Solution 10 - Android
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.
Solution 11 - Android
Just need to add @NoArgsConstructor
and it works.
Solution 12 - Android
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?
Solution 13 - Android
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
}
}
Solution 14 - Android
Bek's answer is correct.
But in-case someone is trying to use immutable class in restcontroller i.e they are using lombok's @value
then you need to add lombok.anyConstructor.addConstructorProperties=true
You can create a file named lombok.config
in the same location where the root pom.xml is present and add this line into the file
Solution 15 - Android
Be carefull with Lombok, expecially with @Builder.
what fixed the issue for me was :
@JsonDeserialize(builder = X.XBuilder.class)
class X{
@JsonPOJOBuilder(withPrefix = "")
public static class XBuilder{
}
}
I hope it will make your life easier
Solution 16 - Android
If you are using LOMBOK. Create a file lombok.config if you don't have one and add this line.
lombok.anyconstructor.addconstructorproperties=true
Solution 17 - Android
Add Constructor in class OR if you are using pojo add @NoArgsConstructor @AllArgsConstructor
Also include JsonProperty -
@JsonProperty("name") private List<Employee> name;
Solution 18 - Android
I got the same error and after I added a constructor without parameters and then the problem was solved.
Solution 19 - Android
If you are using Unirest as the http library, using the GsonObjectMapper
instead of the JacksonObjectMapper
will also work.
<!-- https://mvnrepository.com/artifact/com.konghq/unirest-object-mappers-gson -->
<dependency>
<groupId>com.konghq</groupId>
<artifactId>unirest-object-mappers-gson</artifactId>
<version>2.3.17</version>
</dependency>
Unirest.config().objectMapper = GsonObjectMapper()
Solution 20 - Android
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
Solution 21 - Android
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,
...
Solution 22 - Android
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
Solution 23 - Android
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']
Solution 24 - Android
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
Solution 25 - Android
I got the same error and the problem was that my model didn't implement Serializable, so check this as well, might help since this is also one of the reason.
Solution 26 - Android
I also faced the exception in Kotlin. If you're still having problem after applying KotlinModule, you might (though not quite probably) have value class somewhere.
Solution 27 - Android
I'm adding my answer, because I myself, due to my inattention, encountered this error.
Accidentally introduced the wrong serializer through the import of a static object and for a long time could not understand what was the reason. Maybe this will help someone else.
// Wrong serializer via static object import
import static org.keycloak.util.JsonSerialization.mapper;
Be careful.
Solution 28 - Android
For cases where we don't have a default construct for example when working with immutable obejects, Jackson by default will not be able to deserialize JSON to the object.
We can resolve this using some annotations like @JsonCreator
which can help Jackson to know how to deserialize a given JSON.
A sample code will look like:
package com.test.hello;
import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
public class Payment {
private final Card card;
private final Amount amount;
@JsonCreator(mode = JsonCreator.Mode.PROPERTIES)
public Payment(@JsonProperty("card") Card card, @JsonProperty("amount") Amount amount) {
this.card = card;
this.amount = amount;
}
public Card getCard() {
return card;
}
public Amount getAmount() {
return amount;
}
}
Solution 29 - Android
by adding @NoArgsConstructor
, it will fix the issue.
Because compiler will add the default constructor if we have not provided any constructor, but if we have added any parameterized constructor and missed to add NoArgsConstructor
we will get this exception. We should compulsorily add the default Constructor.