Microsoft Graph API-读取Office 365 SharePoint列表并提取数据(图像) [英] Microsoft Graph API - Read Office 365 SharePoint List and Pull Data (Images)

问题描述

请参阅以下文章: Microsoft Graph API-Office 365访问SharePoint嵌套文件夹项目

我可以通过Graph API获取图像列表.我有一个MVC Azure应用，正在其中进行这些Graph API调用.

I'm able to get a list of Images via the Graph API. I have an MVC Azure App where I'm making these Graph API calls.

但是，当我尝试通过webUrl属性访问Image时，访问被拒绝.

However when I try to access the Image via the webUrl property, I get access denied.

我已经能够通过使用我可以访问的@microsoft.graph.downloadUrl属性来解决此问题，并通过HttpClient下载它，将其转换为字节数组并转换为缩略图.

I've been able to get around this by using the @microsoft.graph.downloadUrl property which I can access, download it via HttpClient convert to Byte Array and transform into a Thumbnail.

但是，理想情况下，我只能使用我的MVC网站对图形端点进行切片和切块，然后通过管道输出webUrl，因此我不必处理调整大小或存储图像字节数据的情况.

However ideally I would just be able to use my MVC site to slice and dice the graph endpoint, then just pipe out webUrl so I don't have to handle resizing or storing the image byte data.

首先，为什么webUrl返回访问被拒绝?

First, why is webUrl return Access Denied?

第二，仅通过我的MVC应用通过管道传输图像URL的最佳方法是什么?我不想负责存储/变换图像.数据需要公开访问.

Second, what would the best approach to just pipe the Image URL through my MVC App? I don't want to be responsible for housing/transforming the image. The data needs to be accessed publicly.

推荐答案

有两种方法可以做到这一点，但是鉴于您要显示缩略图，我来看看

There are a couple of ways to do this but given that you're looking to show a thumbnail, I'd take a look at /thumbnails endpoint:

GET /sites/{site-id}/drive/items/{item-id}/thumbnails

您可以将其与/content端点结合使用来检索二进制文件本身:

You can use this in conjunction with the /content endpoint to retrieve the binary itself:

GET /me/drive/items/{item-id}/thumbnails/{thumb-id}/{size}/content

关于如何处理二进制结果，我通常在后端使用Base64对其进行编码，然后将数据URL返回给客户端.您还可以缓存此结果，并让您的方法在向Graph发出新请求之前简单地检查有效的缓存副本.

As for what to do with the binary result, I typically Base64 encode it on the backend and return a Data URL to the client. You can also cache this result and have your method simply check for a valid cached copy before making a new request to Graph.

这对于数据非常小的个人资料照片"和缩略图"特别有效.

This works particularly well with Profile Photos and Thumbnails where the data is pretty small.

如何使用.NET Graph Client SDK在C#中执行此操作的示例:

An example of how you might do this in C# using the .NET Graph Client SDK:

var imageStream = await graphClient.Me
    .Photo
    .Content
    .Request()
    .GetAsync();

using (var memoryStream = new MemoryStream())
{
    imageStream.CopyTo(memoryStream);
    var base64pic = Convert.ToBase64String(memoryStream.ToArray());
    return "data:image;base64," + base64pic;
}

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