Warm tip: This article is reproduced from serverfault.com, please click
scala implicit scalapb avro4s

How to define and pass implicit encoder of a particular subtype to AvroSchema

发布于 2020-11-12 09:50:30

Is it possible to define and pass Encoder[E] for any subtype E (e.g. any E that extends GeneratedEnum class, in the code instance of E is Color) to AvroSchema[C] where C is some case class that contains E as field.

case class Color(value: Int) extends scalapb.GeneratedEnum // ... it has .name field
case class MyCaseClassWithEnum(color: Color) // ...

implicit def enumEncoder[E <: scalapb.GeneratedEnum]: Encoder[E] = new Encoder[E] {
  override def encode(e: E, schema: Schema, fieldMapper: FieldMapper): AnyRef = e.name
}

val actualSchema = AvroSchema[MyCaseClassWithEnum]

The full source code is here

Basically would like that any subtype instance of GeneratedEnum like Color encodes as String.

Questioner
fpopic
Viewed
11
分享
Dmytro Mitin 2020-11-29 04:50:06

Try to define

implicit val schemaForColor: SchemaFor[Color] = new SchemaFor[Color]() {
  override def schema(fieldMapper: FieldMapper): Schema = 
    SchemaHelper.matchPrimitiveName("java.lang.String").get
}

or

implicit def schemaForColor[E <: GeneratedEnum]: SchemaFor[E] = new SchemaFor[E]() {
  override def schema(fieldMapper: FieldMapper): Schema =
    SchemaHelper.matchPrimitiveName("java.lang.String").get
}

Then the test MyCaseClassWithEnumTest passes.

热门帖子

1
推荐一些好玩的/大众的手游
2
求指教后端项目迁移方案
3
迷你洗衣机是不是都是智商税？
4
求助一个排查了半年没解决的 MySQL order by 子句导致索引失效的问题， 500 多万条记录的小表要查快两分钟
5
个人开发了一款 WordPress 主题： iPao，集成了 AI 总结功能
6
偶然发现奇游加速器会在系统里植入根证书
7
国内有蒲公英替代品推荐吗？
8
语音助手这个东西真的会监听谈话并且上传，从而泄漏隐私吗？
9
出一些有意思的域名-明盘
10
jetbrains 全家桶升级 2024 后，在滚动代码时候感觉有点掉帧

热门github

1
Implementation of paper - YOLOv9: Learning What You Want to Learn Using Programmable Gradient Information
2
A Windows and Office activator using HWID / Ohook / KMS38 / Online KMS activation methods, with a focus on open-source code and fewer antivirus detections.
3
Get up and running with Llama 2, Mistral, Gemma, and other large language models.
4
该项目可以让你通过订阅的方式使用Cloudflare WARP+，自动获取流量。This project enables you to use Cloudflare WARP+ through subscription, automatically acquiring traffic.
5
Multi functional app to find duplicates, empty folders, similar images etc.
6
Xray panel supporting multi-protocol multi-user expire day & traffic & ip limit (Vmess & Vless & Trojan & ShadowSocks & Wireguard)
7
The Free Software Media System
8
lightweight, standalone C++ inference engine for Google's Gemma models.
9
📚 Freely available programming books
10
A collective list of free APIs
11
1️⃣🐝🏎️ The One Billion Row Challenge -- A fun exploration of how quickly 1B rows from a text file can be aggregated with Java
12
🎓 Path to a free self-taught education in Computer Science!
13
Curso para aprender el lenguaje de programación Python desde cero y para principiantes. 75 clases, 37 horas en vídeo, código, proyectos y grupo de chat. Fundamentos, frontend, backend, testing, IA...
14
This repository contains System Design resources which are useful while preparing for interviews and learning Distributed Systems
15
Mamba is a new state space model architecture showing promising performance on information-dense data such as language modeling, where previous subquadratic models fall short of Transformers. It is based on the line of progress on structured state space models, with an efficient hardware-aware design and implementation in the spirit of FlashAttention.