PowerShell发送Multipart请求报400 Bad Request问题排查

请求返回400是以下几个错误共同导致的：

• 接口明确要求请求格式为multipart/form-data，但脚本将整个请求体序列化为JSON，指定application/json作为Content-Type，和接口要求的格式完全不符
• 错误套用curl命令的@文件路径语法，PowerShell的Invoke-WebRequest不识别该写法，无法正确上传文件
• appInfoJson字段被包裹在数组构造符@()中，接口要求该字段为单个JSON对象，不是数组结构
• 所有布尔值、数字类型参数都被写成了带引号的字符串，和接口要求的参数类型不匹配
• 字段名写为autoStart，和接口要求的autostart命名不一致，触发无效参数名错误

# 请求头配置 注意不要手动添加multipart/form-data的Content-Type，Invoke-WebRequest会自动生成带合法boundary的请求头
$Header = @{
   'X-ANYPNT-ENV-ID' =  '4a96af5237cf1b64'
   'X-ANYPNT-ORG-ID' = 'c6583b9fd79234ad'
   'Authorization' = 'Bearer a2b6e09a-5e033d4c46c'
}

# 构造appInfo对象，严格匹配参数类型：布尔值传$true/$false，数字直接传数值，不要统一包成字符串
$appInfo = @{ 
    "domain"                = "testfi-fi-v1-proxy-test" 
    "muleVersion"           = @{"version" = "4.4.0"}
    "properties"            = @{
        "anypoint.platform.client_id" = "8f95f0f5c6b6"
        "secure.key" = "sYf%NslNRH*D$@"
        "env" = "dev"
        "anypoint.platform.client_secret" = "acF0D364be7a"
    }
    "propertiesOptions"     = @{
        "secure.key" = @{"secure" = $true }
        "anypoint.platform.client_secret"= @{"secure" = $true }
    }
    "region"                = "us-west-1"
    "monitoringEnabled"     = $true
    "monitoringAutoRestart" = $true
    "workers"               = @{
        "amount" = 1
        "type" = @{
            "name" = "Micro"
            "weight" = 0.1
            "cpu" = "0.1 vCores"
            "memory" = "500 MB memory"
        }
    }
    "loggingNgEnabled"      = $true
    "persistentQueues"      = $true
}
# 将appInfo序列化为JSON字符串，作为表单的普通字段提交，Depth设为足够大的值避免层级截断
$appInfoJson = $appInfo | ConvertTo-Json -Depth 10 -Compress

# 构造multipart/form-data表单
$Form = @{
    file = Get-Item -Path "E:/actions-runner/workspace/target/sapi-ecm-documents-v1-1.0.2.jar"
    autostart = "true"
    appInfoJson = $appInfoJson
}

try {
    $result = Invoke-WebRequest -Method Post -Uri "https://anypoint.mulesoft.com/cloudhub/api/v2/applications" -Headers $Header -Form $Form
    # 接口返回内容为JSON字符串，需要先反序列化为对象才能读取属性
    $respObj = $result.Content | ConvertFrom-Json
    Write-Output $respObj.domain
    Write-Output $respObj.muleVersion
    Write-Output $respObj.properties
}
catch {
    Write-Output '### 请求异常 ###'
    $ErrorMessage = $_.Exception.Message
    Write-Output "错误信息：$ErrorMessage"
    if ($_.Exception.Response) {
        $reader = New-Object System.IO.StreamReader($_.Exception.Response.GetResponseStream())
        $responseBody = $reader.ReadToEnd()
        Write-Output "接口返回详情：$responseBody"
    }
}

• 不要手动给请求添加multipart/form-data类型的Content-Type头，手动添加会缺少boundary参数直接导致请求失效
• 如果实际接口文档中autostart字段为驼峰命名autoStart，对应修改表单中的键名即可，需严格匹配接口要求的字段大小写
• 上传文件直接通过Get-Item获取本地文件对象传给表单字段即可，不需要手动读取文件流
• PowerShell 5.1及以上版本原生支持-Form参数处理multipart表单，目前主流Windows环境默认搭载的PowerShell版本均满足要求

内容的提问来源于stack exchange，提问作者wehelpdox