Java 17: Difficulty with Custom Serializer for LocalDateTime in Jackson
Quick question that's been bugging me - I'm facing an issue when trying to serialize a `LocalDateTime` object to JSON using Jackson in my Java 17 application. I've defined a custom serializer for `LocalDateTime` to format it in a specific way, but when I serialize my object, I receive the following error: `com.fasterxml.jackson.databind.JsonMappingException: No serializer found for class java.time.LocalDateTime`. Here’s the custom serializer I created: ```java import com.fasterxml.jackson.core.JsonGenerator; import com.fasterxml.jackson.databind.SerializerProvider; import com.fasterxml.jackson.databind.JsonSerializer; import java.io.IOException; import java.time.LocalDateTime; import java.time.format.DateTimeFormatter; public class LocalDateTimeSerializer extends JsonSerializer<LocalDateTime> { private static final DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"); @Override public void serialize(LocalDateTime dateTime, JsonGenerator jsonGenerator, SerializerProvider serializers) throws IOException { jsonGenerator.writeString(dateTime.format(formatter)); } } ``` I then annotated my `LocalDateTime` field in the model class like this: ```java import com.fasterxml.jackson.databind.annotation.JsonSerialize; import java.time.LocalDateTime; public class Event { @JsonSerialize(using = LocalDateTimeSerializer.class) private LocalDateTime eventTime; public Event(LocalDateTime eventTime) { this.eventTime = eventTime; } } ``` When I try to serialize an instance of `Event`, I expected to see the formatted date-time string, but the error above occurs. I’ve made sure that Jackson is properly set up with the necessary dependencies in my `pom.xml`: ```xml <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.12.5</version> </dependency> ``` I've also checked that the `ObjectMapper` is correctly configured in my application. I even tried to add a module for Java 8 time support: ```java import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule; import com.fasterxml.jackson.databind.ObjectMapper; ObjectMapper objectMapper = new ObjectMapper(); objectMapper.registerModule(new JavaTimeModule()); ``` Still, no luck! What am I missing that is causing this serializer issue? Any help would be greatly appreciated!