JSON to Go Struct

Example: JSON to Go

This JSON sample, with the root type named User, produces the Go below using the default options.

{
  "id": 1024,
  "name": "Ada Lovelace",
  "email": "ada@example.com",
  "active": true,
  "score": 98.5,
  "tags": [
    "admin",
    "beta"
  ],
  "address": {
    "city": "London",
    "postcode": "NW1 6XE"
  }
}

package main

type User struct {
	ID      int64    `json:"id"`
	Name    string   `json:"name"`
	Email   string   `json:"email"`
	Active  bool     `json:"active"`
	Score   float64  `json:"score"`
	Tags    []string `json:"tags"`
	Address Address  `json:"address"`
}

type Address struct {
	City     string `json:"city"`
	Postcode string `json:"postcode"`
}

How to convert JSON to Go

1. 1Paste a JSON object or array into the input.
2. 2Select Go as the output language.
3. 3Name the root struct, for example Order.
4. 4Adjust options such as the package name if needed.
5. 5Copy the structs into a .go file and unmarshal with json.Unmarshal.

Struct tags map JSON keys to Go fields

Go fields must be exported (capitalized) for encoding/json to see them, so a key like user_id becomes a field such as UserID with the tag `json:"user_id"`. The tag keeps the wire name exact while the Go name follows Go conventions.

Keep tags when renaming fields. Changing the field name is safe; changing the tag changes what JSON you read and write.

omitempty and pointers for optional fields

`json:"name,omitempty"` drops the key when marshaling if the value is the zero value: empty string, 0, false, nil pointer, or an empty slice or map. On its own it cannot tell "missing" from "zero".

Use a pointer such as *int when you need that distinction: nil means the key was absent or null, while a pointer to 0 means an explicit zero. Plain values are simpler and fine when zero is never a meaningful value.

Numbers, nulls and mixed types

JSON has one number type, so the generator picks int64 or float64 from your sample. If a field is 1 in your sample but 1.5 in production, unmarshaling fails, so check numeric fields against real data.

Fields whose type varies between records may come out as interface{} (any). Replace those with a concrete type or a custom UnmarshalJSON method once you know the real shape.