Deserialize LocalDateTime from String with Jackson

Spen :

I'm trying to deserialize a String to LocalDateTime with Jackson but it doesn't work.

I have a data class with a LocalDateTime field:

@Data
public class Registration {
    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd hh:mm:ss")
    private LocalDateTime timestamp;
}

I added the special Jackson datatype modules:

compile("com.fasterxml.jackson.datatype:jackson-datatype-jsr310")

The serialization works fine with:

new ObjectMapper().registerModule(new JavaTimeModule()).writeValueAsString(registration);

Result String:

{"timestamp":"2018-09-03 10:09:35"}

But the deserialization doesn't work with:

new ObjectMapper().registerModule(new JavaTimeModule()).readValue(json.traverse(), Registration.class)

As error I get:

Cannot deserialize value of type `java.time.LocalDateTime` from String "2018-09-03 10:09:35": 
    Failed to deserialize java.time.LocalDateTime: 
        (java.time.format.DateTimeParseException) Text '2018-09-03 10:09:35' could not be parsed: 
            Unable to obtain LocalDateTime from TemporalAccessor: 
                {MinuteOfHour=9, NanoOfSecond=0, SecondOfMinute=35, MicroOfSecond=0, MilliOfSecond=0, HourOfAmPm=10},
                ISO resolved to 2018-09-03 of type java.time.format.Parsed

What am I missing? I'm confused that the serialization works but the deserialization doesn't.

MWE: (small gradle Java project)

Main.java:

import java.io.IOException;
import java.time.LocalDateTime;

import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.core.TreeNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;

public class Main {

    public static void main(String[] args) throws IOException {
        Registration registration = new Registration();
        registration.setTimestamp(LocalDateTime.now());

         ObjectMapper objectMapper = new ObjectMapper().registerModule(new JavaTimeModule());

         String s = objectMapper.writeValueAsString(registration);
         TreeNode treeNode = objectMapper.readTree(s);

         //Fails here:
         Registration registration1 = objectMapper.readValue(treeNode.traverse(), Registration.class);

        System.out.println(registration1);
    }
}

class Registration {
    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd hh:mm:ss")
    private LocalDateTime timestamp;

    public Registration() {
    }

    public LocalDateTime getTimestamp() {
        return this.timestamp;
    }

    public void setTimestamp(LocalDateTime localDateTime) {
        this.timestamp = localDateTime;
    }
}

build.gradle:

plugins {
    id 'java'
}

group 'dateMWE'
version '1.0-SNAPSHOT'

sourceCompatibility = 10

repositories {
    mavenCentral()
}

dependencies {
    compile("com.fasterxml.jackson.core:jackson-annotations:2.9.6")
    compile("com.fasterxml.jackson.datatype:jackson-datatype-jsr310:2.9.6")
}

Antot :

The problem is not related with JSON deserialization, but rather with the time format string:

pattern = "yyyy-MM-dd hh:mm:ss"

Please notice that the hours are set as hh: this is a 12-hour formatter, which requires "AM" or "PM" values.

If the pattern is changed to

pattern = "yyyy-MM-dd HH:mm:ss"

the problem should be solved.

Deserialize LocalDateTime from String with Jackson

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