发布到具有 Content-Type 的 API：multipart/form-data

尝试 POST 到需要 Content-Type 的 API 时： multipart/form-data，如果您使用 []byte 参数和字符串参数，您可能会遇到问题。提供的错误消息表明重定向问题，与当前问题无关。

解决方案在于使用 multipart 包构造 multipart/form-data 请求正文。这是一个例子：

package main

import (
    "bytes"
    "fmt"
    "io"
    "io/ioutil"
    "mime/multipart"
    "net/http"

    "github.com/ganshane/typeregistry"
)

type FileItem struct {
    Key      string //image_content
    FileName string //test.jpg
    Content  []byte //[]byte
}

func NewPostFile(url string, paramTexts map[string]interface{}, paramFile FileItem) ([]byte, error) {
    // Construct the multipart request body

    bodyBuf := &bytes.Buffer{}
    bodyWriter := multipart.NewWriter(bodyBuf)

    for k, v := range paramTexts {
        bodyWriter.WriteField(k, v.(string))
    }
    fileWriter, err := bodyWriter.CreateFormFile(paramFile.Key, paramFile.FileName)
    if err != nil {
        fmt.Println(err)
        //fmt.Println("Create form file error: ", error)
        return nil, err
    }
    fileWriter.Write(paramFile.Content)
    contentType := bodyWriter.FormDataContentType()
    bodyWriter.Close()
    fmt.Println(bodyBuf.String())

    // Perform the POST request

    resp, err := http.Post(url, contentType, bodyBuf)
    if err != nil {
        return nil, err
    }
    defer resp.Body.Close()
    fmt.Println(resp)

    // Handle the response

    if resp.StatusCode = 300 {
        b, _ := ioutil.ReadAll(resp.Body)
        return nil, fmt.Errorf("[%d %s]%s", resp.StatusCode, resp.Status, string(b))
    }
    respData, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        return nil, err
    }
    fmt.Println(string(respData))
    return respData, nil
}

func main() {
    m := make(map[string]interface{}, 0)
    m["fileName"] = "good"
    m["name"] = typeregistry.Base64ToByte("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 Tl5ufo6erx8vP09fb3 Pn6/8QAHwEAAwEBAQEBAQEBAQAAAAAAAAECAwQFBgcICQoL/8QAtREAAgECBAQDBAcFBAQAAQJ3AAECAxEEBSExBhJBUQdhcRMiMoEIFEKRobHBCSMzUvAVYnLRChYkNOEl8RcYGRomJygpKjU2Nzg5OkNERUZHSElKU1RVVldYWVpjZGVmZ2hpanN0dXZ3eHl6goOEhYaHiImKkpOUlZaXmJmaoqOkpaanqKmqsrO0tba3uLm6wsPExcbHyMnK0tPU1dbX2Nna4uPk5ebn6Onq8vP09fb3 Pn6/9oADAMBAAIRAxEAPwDHooor wD Zz//2Q==")

    paramFile := FileItem{
        Key:      "image_content",
        FileName: "test.jpg",
        Content:  m["name"].([]byte),
    }

    respData, err := NewPostFile("API_URL", m, paramFile)
    if err != nil {
        // Handle error
    }

    fmt.Println(string(respData))
}

在这个示例中，我们使用 NewPostFile 函数构造一个包含 multipart/form-data 的 POST 请求，包括常规表单字段和文件。该函数将 URL、字符串参数映射和文件项作为输入。

来自 API 的响应可以从 respData 变量中检索并根据需要进行处理。错误处理和响应处理代码留给开发人员根据其具体要求来实现。

此解决方案应该解决您在使用 Content-Type: multipart/form-data 发布到 API 时遇到的问题带有 [] 字节参数和字符串参数。