使用MS Graph发带附件邮件时遇MessageAttachmentsCollectionPage不存在错误

你遇到的错误是因为Microsoft Graph SDK 5.x已经移除了MessageAttachmentsCollectionPage类型，不需要额外添加程序集，只需要修改代码适配新版SDK的集合类型规范即可。

修改后的代码： #

// Create the message with attachment.
byte[] contentBytes = System.IO.File.ReadAllBytes(@"C:\test\test.png");
string contentType = "image/png";
// 直接用List<Attachment>替代MessageAttachmentsCollectionPage
List<Attachment> attachments = new List<Attachment>();
attachments.Add(new FileAttachment
{
    ODataType = "#microsoft.graph.fileAttachment",
    ContentBytes = contentBytes,
    ContentType = contentType,
    ContentId = "testing",
    Name = "testing.png"
});
Message email = new Message
{
    Body = new ItemBody
    {
        Content = Resource.Prop_Body + guid,
        ContentType = BodyType.Text,
    },
    Subject = Resource.Prop_Subject + guid.Substring(0, 8),
    ToRecipients = recipients,
    Attachments = attachments
};

// Send the message.
await graphClient.Me.SendMail(email, true).PostAsync();
// 注意：5.x SDK里不再需要Request()方法，直接调用PostAsync即可

补充说明： #

• Graph SDK 5.x对API调用方式和类型做了简化，集合类型统一使用.NET标准集合（如List<T>），不再依赖旧版的*CollectionPage类
• 发送邮件的调用逻辑也做了精简，移除了.Request()链式调用，直接调用.PostAsync()即可完成请求

内容的提问来源于stack exchange，提问作者CDVS