CODEWITHSUNDEEP
javajsonspringparsing
Dr Dave
Dr Dave

Reputation: 580

Parsing JSON to POJO with LocalDateTime using Jackson "Unexpected token (START_OBJECT), expected VALUE_STRING: Expected array or string."

I have read many postings on here on JSON parsing to Java objects and have had my parsing working just fine until I introduced LocalDateTime. I have tried to using the Java 8 parser, the JSR310 module and to build a customization - below describing the roadblocks on each. Any help would be appreciated!

This is my JSON string, creating by Jackson from another POJO:

{"validEscortsWTheirSpecReqs":"MAYBE",
 "modifiedDateTimeNeedToBeThere":     
    {"dayOfMonth":6,"dayOfWeek":"MONDAY","month":"FEBRUARY","year":2017,
     "hour":10,"minute":1,"second":24,"nano":0,"dayOfYear":37,"monthValue":2,
     "chronology":{"id":"ISO","calendarType":"iso8601"}
    }
}

which generates 

com.fasterxml.jackson.databind.JsonMappingException: Unexpected token (START_OBJECT), expected VALUE_STRING: Expected array or string. at 
...
    at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:270)
    at com.fasterxml.jackson.databind.DeserializationContext.wrongTokenException(DeserializationContext.java:1376)
    at com.fasterxml.jackson.datatype.jsr310.deser.LocalDateTimeDeserializer.deserialize(LocalDateTimeDeserializer.java:118)
    at com.fasterxml.jackson.datatype.jsr310.deser.LocalDateTimeDeserializer.deserialize(LocalDateTimeDeserializer.java:39)
...

called from:

ComputeArrive response = mapper.readValue(responseString, ComputeArrive.class);

Response has the following fields:

Logger logger // should not be mapped by JSON, no getters/setters static final long serialVersionUID = 1L; // " String validEscortsWTheirSpecReqs = "YES" // want mapped LocalDateTime modifiedDateTimeNeedToBeThere // want mapped

I have probably registered too many modules by now, adding them in to try to get it to parse:

    mapper.findAndRegisterModules();
    //mapper           .registerModule(new ParameterNamesModule());
    mapper.registerModule(new Jdk8Module());
    mapper.registerModule(new JavaTimeModule());
    mapper.registerModule(new JSR310Module());

So I have tried to add Spring Boot dependencies to my project and write a customizer for JSR310 (which seems unecessary given the modules above):

@Configuration
public class JacksonConfig {

    @Bean
    @Primary
    public ObjectMapper objectMapper(Jackson2ObjectMapperBuilder builder) {
        ObjectMapper objectMapper = builder.createXmlMapper(false).build();
        objectMapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);
        objectMapper.configure(SerializationFeature.WRITE_DATE_TIMESTAMPS_AS_NANOSECONDS, false);
        return objectMapper;
    }
}

My application has numerous dependencies so I did not want to make anything a "parent" of it and added the following dependencies. However, the class "Jackson2ObjectMapperBuilder" is not being found so the above does not compiles with these dependencies:

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-core</artifactId>
    <version>4.3.5.RELEASE</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-web</artifactId>
    <version>4.3.5.RELEASE</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-beans</artifactId>
    <version>4.3.5.RELEASE</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-context</artifactId>
    <version>4.3.5.RELEASE</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-expression</artifactId>
    <version>4.3.5.RELEASE</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-aop</artifactId>
    <version>4.3.5.RELEASE</version>
</dependency>
<dependency>
    <groupId>aopalliance</groupId>
    <artifactId>aopalliance</artifactId>
    <version>1.0</version>
</dependency>

I am not finding a lot of documentation for "Jackson2ObjectMapperBuilderCustomizer" which may be a replacement for "Jackson2ObjectMapperBuilder" - which could be the issue. Please note that the class above is not instantiated by me because I assume Spring instantiates it.

Any thoughts on how to parse my response would be most appreciated!

Upvotes: 13

Views: 23977

Answers (3)

Jean Dok
Jean Dok

Reputation: 494

As @Tobias said use JavaTimeModule will solve the problem.

Add the JSR310 dependency in your pom xml to allow Jackson to be able to recognize Java 8 Date&Time API data types :

<dependency>
    <groupId>com.fasterxml.jackson.datatype</groupId>
    <artifactId>jackson-datatype-jsr310</artifactId>
</dependency>

You can now use JavaTimeModule in you Jackson configuration like this :

@Configuration
public class JacksonConfig {

    @Bean
    @Primary
    public ObjectMapper objectMapper(Jackson2ObjectMapperBuilder builder) {
        ObjectMapper objectMapper = builder.createXmlMapper(false).build();
        objectMapper.registerModule(new JavaTimeModule());
        objectMapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);
        objectMapper.configure(SerializationFeature.WRITE_DATE_TIMESTAMPS_AS_NANOSECONDS, false);
        return objectMapper;
    }
}

You should use this configuration to serialize and deserialize LocalDate or other Java 8 Date&Time API data types.

Upvotes: -1

Hod Ben-Or
Hod Ben-Or

Reputation: 9

I think the problem is the parsing of the LocalDate, try this:

{
    "validEscortsWTheirSpecReqs":"MAYBE",
    "modifiedDateTimeNeedToBeThere":[6,2,2017]
}

day, month, year represented by integers.

Upvotes: 1

Tobias
Tobias

Reputation: 7380

For me, this problem was solved by adding the JavaTimeModule to the Jackson2ObjectMapperBuilder like this:

@Configuration
public class MyConfiguration {

    @Bean
    @Primary
    public Jackson2ObjectMapperBuilder objectMapperBuilder() {
        Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
        return builder.modulesToInstall(new JavaTimeModule());
    }

}

Then Spring uses this mapper with the registered module.

Upvotes: 7

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