Well-known-struct-tags.md

---
title: Well-known struct tags
---

## Background

Go offers [struct tags](https://go.dev/ref/spec#Tag) which are discoverable via reflection. These enjoy a wide range of use in the standard library in the JSON/XML and other encoding packages.

The community welcomed them and has built ORMs, further encodings, flag parsers and much more around them since, especially for these tasks, single-sourcing is beneficial for data structures.

## Problem description

Due to increased usage of Go and thus Go [struct tags](https://go.dev/ref/spec#Tag), clashes become inevitable.

## Solution

The list below is a best effort to document well-known struct tags used by packages which are available to the public.

## Format of the list

- Struct tag as extracted by calling https://pkg.go.dev/reflect#StructTag.Get with this tag as the `key` argument.
- Documentation link of this package using https://pkg.go.dev

### Example entry

| Tag | Documentation                   |
| --- | ------------------------------- |
| xml | https://pkg.go.dev/encoding/xml |

### Change Management

List entries can be added by anyone who creates a public package where a new tag is used.
List entries can be removed when the links to the package documentation stops working or the author(s) of that package requests it.

## List of well-known struct tags

| Tag          | Documentation                                                                          |
| ------------ | -------------------------------------------------------------------------------------- |
| asn1         | https://pkg.go.dev/encoding/asn1                                                       |
| bigquery     | https://pkg.go.dev/cloud.google.com/go/bigquery                                        |
| bson         | https://pkg.go.dev/go.mongodb.org/mongo-driver/bson                                    |
| cue          | https://pkg.go.dev/cuelang.org/go/cuego                                                |
| datastore    | https://pkg.go.dev/cloud.google.com/go/datastore                                       |
| db           | https://github.com/jmoiron/sqlx                                                        |
| dynamodbav   | https://docs.aws.amazon.com/sdk-for-go/api/service/dynamodb/dynamodbattribute/#Marshal |
| egg          | https://github.com/andrewwphillips/eggql                                               |
| feature      | https://github.com/nikolaydubina/go-featureprocessing                                  |
| gorm         | https://pkg.go.dev/github.com/jinzhu/gorm                                              |
| graphql      | https://github.com/samsarahq/thunder                                                   |
| json         | https://pkg.go.dev/encoding/json                                                       |
| mapstructure | https://pkg.go.dev/github.com/mitchellh/mapstructure                                   |
| parser       | https://pkg.go.dev/github.com/alecthomas/participle                                    |
| properties   | https://pkg.go.dev/github.com/magiconair/properties#Properties.Decode                  |
| protobuf     | https://github.com/golang/protobuf                                                     |
| reform       | https://pkg.go.dev/gopkg.in/reform.v1                                                  |
| spanner      | https://pkg.go.dev/cloud.google.com/go/spanner                                         |
| toml         | https://pkg.go.dev/github.com/pelletier/go-toml                                        |
| url          | https://github.com/google/go-querystring                                               |
| validate     | https://github.com/go-playground/validator                                             |
| xml          | https://pkg.go.dev/encoding/xml                                                        |
| yaml         | https://pkg.go.dev/gopkg.in/yaml.v2                                                    |