PowerShell调用DevOps API获取工作项时缺失Relations字段

核心问题排查 #

你遇到的问题根源在于New-WebRequest函数的几个实现缺陷，导致请求头不符合Azure DevOps API的预期，进而返回不完整的工作项数据：

• GET请求错误设置ContentType：GET请求没有请求体，设置-ContentType属于冗余操作，可能干扰API对请求的解析，导致返回内容缺失关联关系字段。
• 未明确指定Accept请求头：浏览器默认会发送Accept: application/json等头信息，而你的PowerShell请求未明确指定，API可能返回了非预期的响应格式。
• 字符串拼接命令的潜在风险：通过[ScriptBlock]::Create拼接Invoke-WebRequest命令，容易出现参数解析错误（比如URL中的特殊字符处理），导致实际发送的请求与预期不符。

另外，Get-WorkItem函数中存在逻辑错误：判断Fields参数兼容性时，使用了-or而非-and，会导致错误触发参数不兼容的提示。

修正后的代码 #

修正版New-WebRequest函数 #

Function New-WebRequest {
    [CmdletBinding()]
    Param (
        [ValidateNotNullOrEmpty()]
        [ValidateSet("GET", "POST")]
        [string] $Method = "GET",

        [Parameter(Mandatory=$true)]
        [ValidateNotNullOrEmpty()]
        [string] $ApiCall,

        [string] $RequestBody,

        [string] $RequestContentType = "application/json"
    )

    if($ApiCall -notmatch $REGEX_URL) {
        Write-Error "The provided URL ($ApiCall) is not in the correct format"
        Exit 1
    }

    try {
        Write-Debug "API Request Call: [$ApiCall]"
        
        # 构建参数哈希表，避免字符串拼接的解析问题
        $requestParams = @{
            Method           = $Method
            Uri              = $ApiCall
            UseBasicParsing  = $true
            Headers          = @{
                Authorization = "Basic $ENCODED_PAT"
                Accept        = "application/json" # 明确指定接受JSON格式
            }
        }

        # 仅在POST请求且有请求体时，添加ContentType和Body参数
        if ($Method -eq "POST" -and $PSBoundParameters.ContainsKey("RequestBody") -and -not([string]::IsNullOrWhiteSpace($RequestBody))) {
            Write-Debug "API Request Body: [$RequestBody]"
            $requestParams.ContentType = $RequestContentType
            $requestParams.Body = $RequestBody
        }

        $Response = Invoke-WebRequest @requestParams
        $StatusCode = $Response.StatusCode
    }
    catch {
        $StatusCode = $_.Exception.Response.StatusCode.value__
        Write-Error "Error Occured: $_"
    }

    if ($StatusCode -eq 200) {
        $ResponseBody = $Response.Content | ConvertFrom-Json
    } else {
        throw "API Call failed (Status code: $StatusCode)"
    }

    return $ResponseBody
}

修正版Get-WorkItem函数 #

Function Get-WorkItem {
    [CmdletBinding()]
    param (
        [Parameter(Mandatory=$true, Position=0)]
        [ValidateNotNullOrEmpty()]
        [ValidatePattern("\d{5,6}")]
        [string] $Id,

        [ValidateSet("All", "None", "Fields", "Links", "Relations")]
        [string] $Expand = "All",

        [string[]] $Fields,

        [switch] $IncludeUpdates
    )

    Write-Debug "Retrieving Work Item [$Id]..."
    $ApiCall = "$API_BASE_URL/wit/workitems/$($Id)?"

    $Params = @("`$expand=$Expand")
    if($PSBoundParameters.ContainsKey("Fields")) {
        # 修正逻辑判断：只有当Expand既不是None也不是Links时才报错
        if($Expand -ne "None" -and $Expand -ne "Links" ) {
            Write-Error "The 'Fields' parameter can be used only if 'Expand' is 'None' or 'Links' as per API definition"
        } else {
            $Params += "fields=$($Fields -Join ",")"
        }
    }

    $ApiCall = Add-APIPart -URL $ApiCall -Params $Params

    $Body = New-WebRequest -ApiCall $ApiCall

    if($PSBoundParameters.ContainsKey("IncludeUpdates")) {
        $Call = "$API_BASE_URL/wit/workitems/$Id/updates"
        $Updates = (New-WebRequest -ApiCall $Call).Value
    }

    return if ($null -eq $Updates) {
        $Body
    } else {
        @{
            Body = $Body;
            Updates = $Updates;
        }
    }
}

验证步骤 #

1. 运行修正后的代码，调用Get-WorkItem -Id <工作项ID>（默认Expand=All），检查返回结果是否包含Relations字段。
2. 若仍有问题，可在New-WebRequest中添加Write-Debug $Response.Headers，对比浏览器请求头与PowerShell请求头的差异，进一步排查。

内容的提问来源于stack exchange，提问作者Fabrizio