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Fix #376: add factory methods/constructor for OffsetDateTime ser/deser with custom formatter #379

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Nov 17, 2025
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Fix #376: add factory methods/constructor for OffsetDateTime ser/deser with custom formatter #379

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e010dfb
Fix #376: add factory methods/constructor for OffsetDateTime ser/dese…
cowtowncoder Nov 17, 2025
41753dd
Rewrite serializer side
cowtowncoder Nov 17, 2025
53eed8e
Refactor deser side too
cowtowncoder Nov 17, 2025
739f8ec
Add release notes
cowtowncoder Nov 17, 2025
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17 changes: 10 additions & 7 deletions datetime/src/main/java/com/fasterxml/jackson/datatype/jsr310/deser/InstantDeserializer.java
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Expand Up @@ -200,12 +200,12 @@ protected InstantDeserializer(Class<T> supportedType,
*/
@Deprecated()
protected InstantDeserializer(Class<T> supportedType,
DateTimeFormatter formatter,
Function<TemporalAccessor, T> parsedToValue,
Function<FromIntegerArguments, T> fromMilliseconds,
Function<FromDecimalArguments, T> fromNanoseconds,
BiFunction<T, ZoneId, T> adjust,
boolean replaceZeroOffsetAsZ
DateTimeFormatter formatter,
Function<TemporalAccessor, T> parsedToValue,
Function<FromIntegerArguments, T> fromMilliseconds,
Function<FromDecimalArguments, T> fromNanoseconds,
BiFunction<T, ZoneId, T> adjust,
boolean replaceZeroOffsetAsZ
) {
this(supportedType, formatter, parsedToValue, fromMilliseconds, fromNanoseconds,
adjust, replaceZeroOffsetAsZ,
Expand Down Expand Up @@ -299,8 +299,11 @@ protected InstantDeserializer(InstantDeserializer<T> base,
_alwaysAllowStringifiedDateTimestamps = features.isEnabled(JavaTimeFeature.ALWAYS_ALLOW_STRINGIFIED_DATE_TIMESTAMPS);
}

/**
* NOTE: {@code public} since 2.21
*/
@Override
protected InstantDeserializer<T> withDateFormat(DateTimeFormatter dtf) {
public InstantDeserializer<T> withDateFormat(DateTimeFormatter dtf) {
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@cowtowncoder cowtowncoder Nov 17, 2025

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This is the actual fix for deserialization.

if (dtf == _formatter) {
return this;
}
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22 changes: 22 additions & 0 deletions ...ime/src/main/java/com/fasterxml/jackson/datatype/jsr310/ser/OffsetDateTimeSerializer.java
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Expand Up @@ -35,6 +35,28 @@ public OffsetDateTimeSerializer(OffsetDateTimeSerializer base, Boolean useTimest
super(base, useTimestamp, base._useNanoseconds, formatter, shape);
}

/**
* Method for constructing a new {@code OffsetDateTimeSerializer} with settings
* of this serializer but with custom {@link DateTimeFormatter} overrides.
* Commonly used on {@code INSTANCE} like so:
*<pre>
* DateTimeFormatter dtf = new DateTimeFormatterBuilder()
* .append(DateTimeFormatter.ISO_LOCAL_DATE)
* .appendLiteral('T')
* // and so on
* .toFormatter();
* OffsetDateTimeSerializer ser = OffsetDateTimeSerializer.INSTANCE
* .withFormatter(dtf);
* // register via Module
*</pre>
*
* @since 2.21
*/
public OffsetDateTimeSerializer withFormatter(DateTimeFormatter formatter)
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@cowtowncoder cowtowncoder Nov 17, 2025

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This is the actual fix for serialization.

{
return new OffsetDateTimeSerializer(this, _useTimestamp, formatter, _shape);
}

@Override
protected JSR310FormattedSerializerBase<?> withFormat(Boolean useTimestamp,
DateTimeFormatter formatter, JsonFormat.Shape shape)
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97 changes: 93 additions & 4 deletions ...me/src/test/java/com/fasterxml/jackson/datatype/jsr310/deser/OffsetDateTimeDeserTest.java
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Expand Up @@ -13,11 +13,11 @@

import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.annotation.JsonFormat.Feature;

import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.ObjectReader;
import com.fasterxml.jackson.databind.SerializationFeature;

import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.module.SimpleModule;
import com.fasterxml.jackson.databind.exc.MismatchedInputException;
import com.fasterxml.jackson.datatype.jsr310.DecimalUtils;
import com.fasterxml.jackson.datatype.jsr310.MockObjectConfiguration;
Expand Down Expand Up @@ -873,4 +873,93 @@ private static ZoneOffset getOffset(OffsetDateTime date, ZoneId zone)
private static String offsetWithoutColon(String string){
return new StringBuilder(string).deleteCharAt(string.lastIndexOf(":")).toString();
}

/*
/**********************************************************************
/* Tests for custom formatter (modules-java8#376)
/**********************************************************************
*/

@Test
public void testDeserializationWithCustomFormatter() throws Exception
{
// Create a custom formatter that can parse ISO_LOCAL_DATE_TIME and default offset to 0
DateTimeFormatter customFormatter = new java.time.format.DateTimeFormatterBuilder()
.append(DateTimeFormatter.ISO_LOCAL_DATE_TIME)
.optionalStart()
.parseLenient()
.appendOffsetId()
.parseStrict()
.optionalEnd()
.parseDefaulting(java.time.temporal.ChronoField.OFFSET_SECONDS, 0)
.toFormatter();

// Create custom deserializer with the custom formatter
InstantDeserializer<OffsetDateTime> customDeserializer =
InstantDeserializer.OFFSET_DATE_TIME.withDateFormat(customFormatter);

// Create a custom module to override the default deserializer
SimpleModule customModule = new SimpleModule("CustomOffsetDateTimeModule")
.addDeserializer(OffsetDateTime.class, customDeserializer);

// Add both JavaTimeModule (for other types) and our custom module
// The custom module will override OffsetDateTime deserialization
ObjectMapper mapper = mapperBuilder()
.addModule(customModule)
.build();

// Test deserializing date-time without offset (should default to +00:00)
// This is the main use case from issue #376 - parsing ISO_LOCAL_DATE_TIME with default offset
String jsonWithoutOffset = q("2025-01-01T22:01:05");
OffsetDateTime result = mapper.readValue(jsonWithoutOffset, OffsetDateTime.class);

assertNotNull(result);
assertEquals(2025, result.getYear());
assertEquals(1, result.getMonthValue());
assertEquals(1, result.getDayOfMonth());
assertEquals(22, result.getHour());
assertEquals(1, result.getMinute());
assertEquals(5, result.getSecond());
assertEquals(ZoneOffset.UTC, result.getOffset());

// Test that standard ISO format with offset still works
String jsonWithOffset = q("2025-01-01T22:01:05+02:00");
OffsetDateTime resultWithOffset = mapper.readValue(jsonWithOffset, OffsetDateTime.class);

assertNotNull(resultWithOffset);
assertEquals(2025, resultWithOffset.getYear());
// Verify parsing succeeded - the exact time may be adjusted based on offset conversion
assertTrue(resultWithOffset.toInstant().equals(OffsetDateTime.parse("2025-01-01T22:01:05+02:00").toInstant()));
}

@Test
public void testDeserializationWithCustomFormatterRoundTrip() throws Exception
{
// Create a custom formatter that can parse ISO_LOCAL_DATE_TIME and default offset to 0
DateTimeFormatter customFormatter = new java.time.format.DateTimeFormatterBuilder()
.append(DateTimeFormatter.ISO_LOCAL_DATE_TIME)
.optionalStart()
.parseLenient()
.appendOffsetId()
.parseStrict()
.optionalEnd()
.parseDefaulting(java.time.temporal.ChronoField.OFFSET_SECONDS, 0)
.toFormatter();

InstantDeserializer<OffsetDateTime> customDeserializer =
InstantDeserializer.OFFSET_DATE_TIME.withDateFormat(customFormatter);
SimpleModule customModule = new SimpleModule("CustomOffsetDateTimeModule")
.addDeserializer(OffsetDateTime.class, customDeserializer);

ObjectMapper mapper = mapperBuilder()
.addModule(customModule)
.build();

// Verify standard ISO format still works
OffsetDateTime original = OffsetDateTime.of(2025, 1, 1, 22, 1, 5, 0, ZoneOffset.UTC);
String json = mapper.writeValueAsString(original);
OffsetDateTime roundTripped = mapper.readValue(json, OffsetDateTime.class);

assertIsEqual(original, roundTripped);
}
}
101 changes: 101 additions & 0 deletions datetime/src/test/java/com/fasterxml/jackson/datatype/jsr310/ser/OffsetDateTimeSerTest.java
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Expand Up @@ -3,8 +3,10 @@
import java.time.Instant;
import java.time.OffsetDateTime;
import java.time.ZoneId;
import java.time.ZoneOffset;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeFormatterBuilder;
import java.time.temporal.Temporal;
import java.util.TimeZone;

Expand All @@ -13,6 +15,7 @@
import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.databind.module.SimpleModule;
import com.fasterxml.jackson.datatype.jsr310.DecimalUtils;
import com.fasterxml.jackson.datatype.jsr310.MockObjectConfiguration;
import com.fasterxml.jackson.datatype.jsr310.ModuleTestBase;
Expand Down Expand Up @@ -284,4 +287,102 @@ public void testShapeInt() throws Exception {
String json1 = newMapper().writeValueAsString(new Pojo1());
assertEquals("{\"t1\":1651053600000,\"t2\":1651053600.000000000}", json1);
}

/*
/**********************************************************************
/* Tests for custom formatter (modules-java8#376)
/**********************************************************************
*/

@Test
public void testSerializationWithCustomFormatter() throws Exception
{
// Create a custom formatter that displays only 3 digits of nano-seconds instead of 9
// Use ISO_LOCAL_DATE and ISO_LOCAL_TIME separately to control nanosecond precision
DateTimeFormatter customFormatter = new DateTimeFormatterBuilder()
.append(DateTimeFormatter.ISO_LOCAL_DATE)
.appendLiteral('T')
.appendValue(java.time.temporal.ChronoField.HOUR_OF_DAY, 2)
.appendLiteral(':')
.appendValue(java.time.temporal.ChronoField.MINUTE_OF_HOUR, 2)
.optionalStart()
.appendLiteral(':')
.appendValue(java.time.temporal.ChronoField.SECOND_OF_MINUTE, 2)
.optionalStart()
.appendFraction(java.time.temporal.ChronoField.NANO_OF_SECOND, 3, 3, true)
.optionalEnd()
.optionalEnd()
.appendOffsetId()
.toFormatter();

// Create a date with nanoseconds (123456789 nanos = .123456789 seconds)
OffsetDateTime date = OffsetDateTime.of(2025, 1, 1, 22, 1, 5, 123456789, ZoneOffset.UTC);
String json = _mapper(customFormatter).writeValueAsString(date);

// Should output with only 3 digits of nano precision (.123 instead of .123456789)
assertEquals(q("2025-01-01T22:01:05.123Z"), json);
}

@Test
public void testSerializationWithCustomFormatterNoNanos() throws Exception
{
// Create a formatter without nanoseconds
DateTimeFormatter customFormatter = new DateTimeFormatterBuilder()
.append(DateTimeFormatter.ISO_LOCAL_DATE)
.appendLiteral('T')
.appendValue(java.time.temporal.ChronoField.HOUR_OF_DAY, 2)
.appendLiteral(':')
.appendValue(java.time.temporal.ChronoField.MINUTE_OF_HOUR, 2)
.optionalStart()
.appendLiteral(':')
.appendValue(java.time.temporal.ChronoField.SECOND_OF_MINUTE, 2)
.optionalEnd()
.appendOffsetId()
.toFormatter();

OffsetDateTime date = OffsetDateTime.of(2025, 1, 1, 22, 1, 5, 123456789, ZoneOffset.UTC);
String json = _mapper(customFormatter).writeValueAsString(date);

// Should output without nanoseconds
assertEquals(q("2025-01-01T22:01:05Z"), json);
}

@Test
public void testSerializationWithCustomFormatterAndOffset() throws Exception
{
// Create a custom formatter that displays only 3 digits of nano-seconds
DateTimeFormatter customFormatter = new DateTimeFormatterBuilder()
.append(DateTimeFormatter.ISO_LOCAL_DATE)
.appendLiteral('T')
.appendValue(java.time.temporal.ChronoField.HOUR_OF_DAY, 2)
.appendLiteral(':')
.appendValue(java.time.temporal.ChronoField.MINUTE_OF_HOUR, 2)
.optionalStart()
.appendLiteral(':')
.appendValue(java.time.temporal.ChronoField.SECOND_OF_MINUTE, 2)
.optionalStart()
.appendFraction(java.time.temporal.ChronoField.NANO_OF_SECOND, 3, 3, true)
.optionalEnd()
.optionalEnd()
.appendOffsetId()
.toFormatter();


// Create a date with a non-UTC offset
OffsetDateTime date = OffsetDateTime.of(2025, 1, 1, 22, 1, 5, 123456789, ZoneOffset.ofHours(5));
String json = _mapper(customFormatter).writeValueAsString(date);

// Should output with offset +05:00 and 3 digits of nano precision
assertEquals(q("2025-01-01T22:01:05.123+05:00"), json);
}

private ObjectMapper _mapper(DateTimeFormatter dtf) {
OffsetDateTimeSerializer customSerializer = OffsetDateTimeSerializer.INSTANCE
.withFormatter(dtf);
SimpleModule customModule = new SimpleModule("CustomOffsetDateTimeModule")
.addSerializer(OffsetDateTime.class, customSerializer);
return mapperBuilder()
.addModule(customModule)
.build();
}
}
3 changes: 3 additions & 0 deletions release-notes/VERSION-2.x
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Expand Up @@ -14,6 +14,9 @@ Modules:
negative timestamps incorrectly
(reported by Kevin M)
(fix by @cowtowncoder, w/ Claude code)
#376: Allow specifying custom `DateTimeFormatter` for `OffsetDateTime` ser/deser
(new constructors?)
(requested by @ZIRAKrezovic)

No changes since 2.20

Expand Down
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