如何通过Microsoft Graph向Teams频道发送公告类型聊天消息

你遇到这个报错是三个配置错误导致的，和附件ID只读的说法没有关系：

• Attachments 参数要求传入数组类型，你原代码里传的是单个哈希表对象，接口无法正确解析附件的顶层结构
• 附件ID是附件对象的顶层属性，和contentType、content平级，你原代码里把id注释/放在了content子对象内部，接口识别不到
• 公告附件的ID不需要系统生成，你自己生成随机GUID即可，只要保证附件对象的id值，和HTML正文里<attachment>标签的id属性值完全一致就可以正常识别。

Select-MgProfile beta
Connect-MgGraph -Scopes "ChannelMessage.Send"

# 生成随机GUID作为附件匹配ID
$announcementAttachmentId = [guid]::NewGuid().ToString()

# 注意Attachments是数组，id放在附件对象顶层
$attachments = @(
    @{
        id          = $announcementAttachmentId
        contentType = "application/vnd.microsoft.teams.messaging-announcementBanner"
        content     = @{
            title            = "This is an important announcement"
            cardImageType    = "colorTheme"
            cardImageDetails = @{
                colorTheme = "periwinkleBlue"
            } | ConvertTo-Json -Compress
        }
    }
)

$bodyContent = @"
<attachment id="$announcementAttachmentId"></attachment>
<div>Hi all, 这里填写公告正文内容</div>
"@

$params = @{
    ChannelId   = "替换为实际频道ID"
    TeamId      = "替换为实际团队ID"
    Attachments = $attachments
    Importance  = "high"
    Body        = @{
        ContentType = "html"
        Content     = $bodyContent
    }
}

New-MgTeamChannelMessage @params

如果不用PowerShell模块，可以直接向beta版Graph接口发POST请求，请求地址为https://graph.microsoft.com/beta/teams/{team-id}/channels/{channel-id}/messages，请求体结构如下：

{
    "importance": "high",
    "body": {
        "contentType": "html",
        "content": "<attachment id=\"e5718d51-22a3-4c28-9978-1f3aexample\"></attachment><div>Hi all, 公告正文内容</div>"
    },
    "attachments": [
        {
            "id": "e5718d51-22a3-4c28-9978-1f3aexample",
            "contentType": "application/vnd.microsoft.teams.messaging-announcementBanner",
            "content": "{\"title\":\"This is an important announcement\",\"cardImageType\":\"colorTheme\",\"cardImageDetails\":\"{\\\"colorTheme\\\":\\\"periwinkleBlue\\\"}\"}"
        }
    ]
}

• 内置可选的公告主题色除了periwinkleBlue，还支持red、green、orange、purple、darkBlue
• 如果需要使用自定义图片作为公告头图，把cardImageType改为uploadedImage，在cardImageDetails中传入图片的托管URL、宽高参数即可
• 公告类型消息目前仅在beta版本Graph中支持，v1.0版本暂未开放对应能力
• 权限除了委派权限ChannelMessage.Send，使用应用权限ChannelMessage.Send.All也可正常调用

内容的提问来源于stack exchange，提问作者Daniel