[
https://issues.apache.org/jira/browse/TINKERPOP-3237?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18066987#comment-18066987
]
ASF GitHub Bot commented on TINKERPOP-3237:
-------------------------------------------
DR1N0 opened a new pull request, #3335:
URL: https://github.com/apache/tinkerpop/pull/3335
## Summary
This PR adds support for serializing custom types in gremlin-go, bringing it
to **feature parity with the Java driver** and completing the custom type
support that currently only includes deserialization. This implements the
official GraphBinary specification for custom types, enabling full round-trip
support for custom graph database types.
## Motivation
While gremlin-go supports deserializing custom types via
`RegisterCustomTypeReader()`, it lacks the corresponding serialization
capability. This creates an asymmetry where users can read custom types from
server responses but cannot write them in requests. The **Java driver already
has full custom type support** (both `CustomTypeSerializer` reader and writer),
and this PR brings gremlin-go to the same level.
## Changes
### New API Functions
- `RegisterCustomTypeWriter(valueType reflect.Type, typeName string, writer
CustomTypeWriter)` - Registers a custom serializer for a specific type
- `UnregisterCustomTypeWriter(valueType reflect.Type)` - Unregisters a
custom serializer
### New Types
- `CustomTypeWriter` - Function type for user-provided serialization
functions
- `CustomTypeInfo` - Struct holding type metadata (name and writer function)
### Implementation Details
- Added `customTypeWriter()` function to handle GraphBinary custom type
format (type_code=0x00, type_name, value)
- Modified `getType()` to detect registered custom types before checking
built-in types
- Modified `write()` to properly handle custom type format, matching the
Java implementation in `GraphBinaryWriter.java`:
```java
if (serializer instanceof CustomTypeSerializer) {
buffer.writeBytes(customTypeCodeBytes); // 0x00
writeValue(customTypeSerializer.getTypeName(), buffer, false);
customTypeSerializer.write(value, buffer, this);
}
```
### GraphBinary Format Compliance
The implementation follows the exact format used by Java's
`GraphBinaryWriter`:
- **Type code**: `0x00` (DataType.CUSTOM)
- **Type name**: UTF-8 string with length prefix
- **Value**: Custom-serialized data
This ensures **cross-driver compatibility** - custom types serialized by
gremlin-go can be deserialized by Java drivers and vice versa.
### Updated Files
- `gremlin-go/driver/serializer.go` - Added type definitions and
registration functions
- `gremlin-go/driver/graphBinary.go` - Added custom type writer
implementation and modified type detection
- `gremlin-go/driver/serializer_test.go` - Added test cases following
existing patterns
- `CHANGELOG.asciidoc` - Added changelog entry
## Test Coverage
Tests follow the same pattern as existing custom type reader tests:
- **Success case** in `TestSerializer`: "test serialized request message w/
custom type"
- **Failure case** in `TestSerializerFailures`: "test unregistered custom
type writer failure"
All tests pass:
```
=== RUN TestSerializer/test_serialized_request_message_w/_custom_type
-
> Add Custom Type Writer/Serializer API for gremlin-go
> ----------------------------------------------------
>
> Key: TINKERPOP-3237
> URL: https://issues.apache.org/jira/browse/TINKERPOP-3237
> Project: TinkerPop
> Issue Type: Improvement
> Components: go
> Affects Versions: 3.8.0
> Reporter: Haiyu Wang
> Priority: Major
> Fix For: 3.8.1
>
>
> ## Problem
>
> Currently, gremlin-go supports deserializing custom types via
> `RegisterCustomTypeReader()`, but lacks the corresponding functionality to
> serialize custom types when sending requests to the server. This creates an
> asymmetry where users can read custom types from server responses but cannot
> write them in requests.
> **The Java driver already has complete custom type support** through
> `CustomTypeSerializer` in `GraphBinaryWriter.java` and
> `GraphBinaryReader.java`. This gap prevents gremlin-go users from working
> with custom types in graph databases like JanusGraph, which use custom types
> such as `RelationIdentifier`, `Geoshape`, etc.
> ## Current State
> - **Java driver**: ✅ Custom Type Reader + ✅ Custom Type Writer
> - **gremlin-go**: ✅ Custom Type Reader + ❌ Custom Type Writer (incomplete)
> ## Proposed Solution
> Add a `RegisterCustomTypeWriter()` API that mirrors the existing
> `CustomTypeReader` pattern and implements the same GraphBinary custom type
> format used by the Java driver.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
