Graph API批量添加小文件到任务报错：taskFileAttachment类型无法识别

你尝试通过以下C#代码给待办任务添加多个小文件附件并提交到Graph API：

if (attachments != null)
{
    if (attachments.Length > 0)
    {
        _newTask.Attachments = new TodoTaskAttachmentsCollectionPage();
        foreach (var _attachment in attachments)
        {
            _newTask.Attachments.Add(new TaskFileAttachment
            {
                Name = _attachment.FileName,
                ContentBytes = _attachment.ContentBytes,
                ContentType = _attachment.ContentType
            });
        }
    }

}
await _graphServiceClient.Users[idUser].Todo.Lists[idList].Tasks.Request().AddAsync(_newTask);

运行后出现错误：

One or more errors occurred. (One or more errors occurred. (A type named 'microsoft.toDo.taskFileAttachment' could not be resolved by the model. When a model is available, each type name must resolve to a valid type.

虽然参考文档认为TaskFileAttachment是正确类型，但待办任务的附件操作逻辑和邮件不同，问题出在待办任务不支持创建时一并添加附件，必须分两步操作：

解决方案 #

1. 先创建不带附件的待办任务，获取任务ID
2. 针对已创建的任务单独添加每个附件

修正后的代码示例 #

// 第一步：创建不带附件的任务
var createdTask = await _graphServiceClient.Users[idUser].Todo.Lists[idList].Tasks.Request().AddAsync(_newTask);

// 第二步：为已创建的任务添加附件
if (attachments != null && attachments.Length > 0)
{
    foreach (var _attachment in attachments)
    {
        var fileAttachment = new TaskFileAttachment
        {
            Name = _attachment.FileName,
            ContentBytes = _attachment.ContentBytes,
            ContentType = _attachment.ContentType
        };
        await _graphServiceClient.Users[idUser].Todo.Lists[idList].Tasks[createdTask.Id].Attachments.Request().AddAsync(fileAttachment);
    }
}

额外注意事项 #

• 确保使用Beta版本的Graph SDK，待办任务附件接口目前仅在Beta版本中提供支持
• 邮件附件支持创建时一并添加，但待办任务的附件接口设计不同，必须分开执行操作

内容的提问来源于stack exchange，提问作者Salvador Ruiz Guevara