feat: support vision

README.md

@@ -95,6 +95,68 @@ func main() {
 }
 ```
 
+### Messages Vision example usage:
+
+```go
+package main
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/liushuangls/go-anthropic"
+)
+
+func main() {
+	client := anthropic.NewClient("your anthropic apikey")
+
+	imagePath := "xxx"
+	imageMediaType := "image/jpeg"
+	imageFile, err := os.Open(imagePath)
+	if err != nil {
+		panic(err)
+	}
+	imageData, err := io.ReadAll(imageFile)
+	if err != nil {
+		panic(err)
+	}
+
+	resp, err := client.CreateMessages(context.Background(), anthropic.MessagesRequest{
+		Model: anthropic.ModelClaude3Opus20240229, // only claude 3 model can use vision
+		Messages: []anthropic.Message{
+			{
+				Role: anthropic.RoleUser,
+				Content: []any{
+					anthropic.MessageImageContent{
+						Type: "image",
+						Source: anthropic.MessageImageContentSource{
+							Type:      "base64",
+							MediaType: imageMediaType,
+							Data:      imageData,
+						},
+					},
+					anthropic.MessageTextContent{
+						Type: "text",
+						Text: "Describe this image.",
+					},
+				},
+			},
+		},
+		MaxTokens: 1000,
+	})
+	if err != nil {
+		var e *anthropic.APIError
+		if errors.As(err, &e) {
+			fmt.Printf("Messages error, type: %s, message: %s", e.Type, e.Message)
+		} else {
+			fmt.Printf("Messages error: %v\n", err)
+        }
+		return
+	}
+	fmt.Println(resp.Content[0].Text)
+}
+```
+
 ## Acknowledgments
 The following project had particular influence on go-anthropic is design.
 

message.go

@@ -42,7 +42,23 @@ func (m *MessagesRequest) SetTopK(k int) {
 
 type Message struct {
 	Role    string `json:"role"`
-	Content string `json:"content"`
+	Content any    `json:"content"` // Content can be string, MessageTextContent or MessageImageContent or slice
+}
+
+type MessageTextContent struct {
+	Type string `json:"type"`
+	Text string `json:"text"`
+}
+
+type MessageImageContent struct {
+	Type   string                    `json:"type"`
+	Source MessageImageContentSource `json:"source"`
+}
+
+type MessageImageContentSource struct {
+	Type      string `json:"type"`
+	MediaType string `json:"media_type"`
+	Data      any    `json:"data"`
 }
 
 type MessagesResponse struct {

message_test.go

@@ -2,6 +2,7 @@ package anthropic_test
 
 import (
 	"context"
+	"embed"
 	"encoding/json"
 	"errors"
 	"io"
@@ -15,6 +16,9 @@ import (
 	"github.com/liushuangls/go-anthropic/internal/test/checks"
 )
 
+//go:embed internal/test/sources/*
+var sources embed.FS
+
 func TestMessages(t *testing.T) {
 	server := test.NewTestServer()
 	server.RegisterHandler("/v1/messages", handleMessagesEndpoint)
@@ -75,6 +79,60 @@ func TestMessagesTokenError(t *testing.T) {
 	t.Logf("CreateMessages error: %s", err)
 }
 
+func TestMessagesVision(t *testing.T) {
+	server := test.NewTestServer()
+	server.RegisterHandler("/v1/messages", handleMessagesEndpoint)
+
+	ts := server.AnthropicTestServer()
+	ts.Start()
+	defer ts.Close()
+
+	baseUrl := ts.URL + "/v1"
+	client := anthropic.NewClient(
+		test.GetTestToken(),
+		anthropic.WithBaseURL(baseUrl),
+	)
+
+	imagePath := "internal/test/sources/ant.jpg"
+	imageMediaType := "image/jpeg"
+	imageFile, err := sources.Open(imagePath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	imageData, err := io.ReadAll(imageFile)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp, err := client.CreateMessages(context.Background(), anthropic.MessagesRequest{
+		Model: anthropic.ModelClaude3Opus20240229,
+		Messages: []anthropic.Message{
+			{
+				Role: anthropic.RoleUser,
+				Content: []any{
+					anthropic.MessageImageContent{
+						Type: "image",
+						Source: anthropic.MessageImageContentSource{
+							Type:      "base64",
+							MediaType: imageMediaType,
+							Data:      imageData,
+						},
+					},
+					anthropic.MessageTextContent{
+						Type: "text",
+						Text: "Describe this image.",
+					},
+				},
+			},
+		},
+		MaxTokens: 1000,
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("CreateMessages resp: %+v", resp)
+}
+
 func handleMessagesEndpoint(w http.ResponseWriter, r *http.Request) {
 	var err error
 	var resBytes []byte