Go SDK

import (
	"github.com/anthropics/anthropic-sdk-go" // imported as anthropic
)

go get github.com/anthropics/anthropic-sdk-go

package main

import (
	"context"
	"fmt"

	"github.com/anthropics/anthropic-sdk-go"
	"github.com/anthropics/anthropic-sdk-go/option"
)

func main() {
	client := anthropic.NewClient(
		option.WithAPIKey("my-anthropic-api-key"), // defaults to os.LookupEnv("ANTHROPIC_API_KEY")
	)
	message, err := client.Messages.New(context.TODO(), anthropic.MessageNewParams{
		MaxTokens: 1024,
		Messages: []anthropic.MessageParam{
			anthropic.NewUserMessage(anthropic.NewTextBlock("What is a quaternion?")),
		},
		Model: anthropic.ModelClaudeOpus5_5,
	})
	if err != nil {
		panic(err.Error())
	}
	for _, block := range message.Content {
		if textBlock, ok := block.AsAny().(anthropic.TextBlock); ok {
			fmt.Println(textBlock.Text)
		}
	}
}

p := anthropic.ExampleParams{
	ID:   "id_xxx",                // required property
	Name: anthropic.String("..."), // optional property

	Point: anthropic.Point{
		X: 0,                // required field will serialize as 0
		Y: anthropic.Int(1), // optional field will serialize as 1
		// ... 省略的非必要欄位將不會被序列化
	},

	Origin: anthropic.Origin{}, // the zero value of [Origin] is considered omitted
}

p.Name = param.Null[string]()       // 'null' instead of string
p.Point = param.NullStruct[Point]() // 'null' instead of struct

param.IsNull(p.Name)  // true
param.IsNull(p.Point) // true

// 若 API 指定了某個型別，
// 但您想傳送其他內容，請使用 [SetExtraFields]：
p.SetExtraFields(map[string]any{
	"x": 0.01, // send "x" as a float instead of int
})

// 傳送數字而非物件
custom := param.Override[anthropic.FooParams](12)

// 只能有一個欄位為非零值，請使用 param.IsOmitted() 檢查欄位是否已設定
type AnimalUnionParam struct {
	OfCat *Cat `json:",omitzero,inline"`
	OfDog *Dog `json:",omitzero,inline"`
}

animal := AnimalUnionParam{
	OfCat: &Cat{
		Name: "Whiskers",
		Owner: PersonParam{
			Address: AddressParam{Street: "3333 Coyote Hill Rd", ZipCode: 0},
		},
	},
}

// 修改欄位
if address := animal.GetOwner().GetAddress(); address != nil {
	address.ZipCode = 94304
}

// 序列化 params（例如用於儲存或轉送）
b, err := json.Marshal(original)
if err != nil {
	panic(err)
}

// 稍後，從已儲存的 JSON 重建 params
var params anthropic.MessageNewParams
if err := params.UnmarshalJSON(b); err != nil {
	panic(err)
}
param.SetJSON(b, &params)

// params.Model 及其他純量欄位會由 UnmarshalJSON 填入。
// params.Tools[0].OfBashTool20250124 為 nil（union 的限制），
// 但原始 JSON 會被保留。當 params 再次被 marshal
// 以進行 API 呼叫時，tools 會正確序列化。
b2, _ := json.Marshal(params)
fmt.Println(string(b) == string(b2)) // true

type Animal struct {
	Name   string `json:"name,nullable"`
	Owners int    `json:"owners"`
	Age    int    `json:"age"`
	JSON   struct {
		Name        respjson.Field
		Owners      respjson.Field
		Age         respjson.Field
		ExtraFields map[string]respjson.Field
	} `json:"-"`
}

raw := `{"owners": 1, "name": null}`

var res Animal
json.Unmarshal([]byte(raw), &res)

// 存取一般欄位

res.Owners // 1
res.Name   // ""
res.Age    // 0

// 選用欄位檢查

res.JSON.Owners.Valid() // true
res.JSON.Name.Valid()   // false
res.JSON.Age.Valid()    // false

// 原始 JSON 值

res.JSON.Owners.Raw()                  // "1"
res.JSON.Name.Raw() == "null"          // true
res.JSON.Name.Raw() == respjson.Null   // true
res.JSON.Age.Raw() == ""               // true
res.JSON.Age.Raw() == respjson.Omitted // true

body := res.JSON.ExtraFields["my_unexpected_field"].Raw()

type AnimalUnion struct {
	// 來自變體 [Dog]、[Cat]
	Owner Person `json:"owner"`
	// 來自變體 [Dog]
	DogBreed string `json:"dog_breed"`
	// 來自變體 [Cat]
	CatBreed string `json:"cat_breed"`
	// ...

	JSON struct {
		Owner respjson.Field
		// ...
	} `json:"-"`
}

// 若為 animal 變體
if animal.Owner.Address.ZipCode == "" {
	panic("missing zip code")
}

// 依變體進行 switch
switch variant := animal.AsAny().(type) {
case Dog:
case Cat:
default:
	panic("unexpected type")
}

_, err := client.Messages.New(context.TODO(), anthropic.MessageNewParams{
	MaxTokens: 1024,
	Messages: []anthropic.MessageParam{{
		Content: []anthropic.ContentBlockParamUnion{{
			OfText: &anthropic.TextBlockParam{
				Text: "What is a quaternion?",
			},
		}},
		Role: anthropic.MessageParamRoleUser,
	}},
	Model: anthropic.ModelClaudeOpus5_5,
})
if err != nil {
	var apierr *anthropic.Error
	if errors.As(err, &apierr) {
		println("Request ID:", apierr.RequestID)
		println(string(apierr.DumpRequest(true)))  // Prints the serialized HTTP request
		println(string(apierr.DumpResponse(true))) // Prints the serialized HTTP response
	}
	panic(err.Error()) // POST "/v1/messages": 400 Bad Request (Request-ID: req_xxx) { ... }
}

// 設定所有請求的預設值：
client := anthropic.NewClient(
	option.WithMaxRetries(0), // default is 2
)

// 針對個別請求覆寫：
// ...
	client.Messages.New(
		context.TODO(),
		anthropic.MessageNewParams{
			MaxTokens: 1024,
			Messages: []anthropic.MessageParam{{
				Content: []anthropic.ContentBlockParamUnion{{
					OfText: &anthropic.TextBlockParam{
						Text: "What is a quaternion?",
					},
				}},
				Role: anthropic.MessageParamRoleUser,
			}},
			Model: anthropic.ModelClaudeOpus5_5,
		},
		option.WithMaxRetries(5),
	)

// 此設定請求的逾時時間，包含所有重試。
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Minute)
defer cancel()
// ...
	client.Messages.New(
		ctx,
		anthropic.MessageNewParams{
			MaxTokens: 1024,
			Messages: []anthropic.MessageParam{{
				Content: []anthropic.ContentBlockParamUnion{{
					OfText: &anthropic.TextBlockParam{
						Text: "What is a quaternion?",
					},
				}},
				Role: anthropic.MessageParamRoleUser,
			}},
			Model: anthropic.ModelClaudeOpus5_5,
		},
		// 此設定每次重試的逾時時間
		option.WithRequestTimeout(20*time.Second),
	)

// 來自檔案系統的檔案
file, err := os.Open("/path/to/file.json")
anthropic.FileUploadParams{
	File: anthropic.File(file, "custom-name.json", "application/json"),
}

// 來自字串的檔案
anthropic.FileUploadParams{
	File: anthropic.File(strings.NewReader("my file contents"), "custom-name.json", "application/json"),
}

iter := client.Messages.Batches.ListAutoPaging(context.TODO(), anthropic.MessageBatchListParams{
	Limit: anthropic.Int(20),
})
// 視需要自動擷取更多頁面。
for iter.Next() {
	messageBatch := iter.Current()
	fmt.Println(messageBatch.ID)
}
if err := iter.Err(); err != nil {
	panic(err.Error())
}

page, err := client.Messages.Batches.List(context.TODO(), anthropic.MessageBatchListParams{
	Limit: anthropic.Int(20),
})
for page != nil {
	for _, batch := range page.Data {
		fmt.Println(batch.ID)
	}
	page, err = page.GetNextPage()
}
if err != nil {
	panic(err.Error())
}

client := anthropic.NewClient(
	// 為用戶端發出的每個請求加入標頭
	option.WithHeader("X-Some-Header", "custom_header_info"),
)

client.Messages.New(context.TODO(), // ...,
	// 覆寫標頭
	option.WithHeader("X-Some-Header", "some_other_custom_header_info"),
	// 使用 sjson 語法，在請求主體中加入未記載於文件的欄位
	option.WithJSONSet("some.json.path", map[string]string{"my": "object"}),
)

// 建立一個變數來儲存 HTTP 回應
var response *http.Response
message, err := client.Messages.New(
	context.TODO(),
	anthropic.MessageNewParams{
		MaxTokens: 1024,
		Messages: []anthropic.MessageParam{{
			Content: []anthropic.ContentBlockParamUnion{{
				OfText: &anthropic.TextBlockParam{
					Text: "What is a quaternion?",
				},
			}},
			Role: anthropic.MessageParamRoleUser,
		}},
		Model: anthropic.ModelClaudeOpus5_5,
	},
	option.WithResponseInto(&response),
)
if err != nil {
	// 處理錯誤
}
fmt.Printf("%+v\n", message.Content)

fmt.Printf("Status Code: %d\n", response.StatusCode)
fmt.Printf("Headers: %+#v\n", response.Header)

var (
	// params 可以是 io.Reader、[]byte、可由 encoding/json 序列化的物件，
	// 或本函式庫中定義的「...Params」結構。
	params map[string]any

	// result 可以是 []byte、*http.Response、可由 encoding/json 反序列化的物件，
	// 或本函式庫中定義的模型。
	result *http.Response
)
err := client.Post(context.Background(), "/unspecified", params, &result)
if err != nil {
	// ...
}

params := FooNewParams{
	ID: "id_xxxx",
	Data: FooNewParamsData{
		FirstName: anthropic.String("John"),
	},
}
client.Foo.New(context.Background(), params, option.WithJSONSet("data.last_name", "Doe"))