如何将文件上传到blob存储并从附件中的cosmosdb文档引用它

Question

我不熟悉CosmosDb和azure blob存储，因为我需要引用一个从CosmosDb中的文档上传到azure blob存储的文件，并在附件部分使用它来保存元数据。

我知道json元数据结构应该是这样的：

{    
   "id":"image13d65101-90c4-4c2a-a423-fbf221c73233",  
   "contentType":"image/jpg",  
   "media":"www.bing.com",  
   "_rid":"rnYYAMVFUAUBAAAAAAAAAEC+LNM=",  
   "_ts":1408056025,  
   "_self":"dbs\/rnYYAA==\/colls\/rnYYAMVFUAU=\/docs\/rnYYAMVFUAUBAAAAAAAAAA==\/attachments\/rnYYAMVFUAUBAAAAAAAAAEC+LNM=",  
   "_etag":"00002a00-0000-0000-0000-53ed3ad90000"  
}

但是如何在将文件上传到azure blob存储时获取对媒体属性的引用，更准确地说，如何将文件从c#上传到azure blob存储并通过将url设置为媒体属性来引用它。

Answer 1

如何将文件从c#上传到azure blob存储并通过将url设置为media属性来引用它。

您可以参考这篇文章设置和检索元数据，您应该在上传后再次获取Blob。

示例代码如下:

        //the code to get the blob again after uploading.
        var blockblob = blobContainer.GetBlockBlobReference(blobname);

        //the code to set medadata.
        blockblob.FetchAttributes();
        blockblob.Metadata["media"] = "www.bing.com";
        blockblob.SetMetadata();

Answer 2

这是我的一个应用程序的示例代码，用于上传到blob存储，然后将对cosmosdb的引用保存为uri，

    public async Task<IActionResult> UploadImageAsync([FromBody] ImageUploadRequest imageRequest)
    {

        if (string.IsNullOrEmpty(imageRequest?.Base64))
        {
            return BadRequest();
        }

        var tokens = imageRequest.Base64.Split(',');
        var ctype = tokens[0].Replace("data:", "");
        var base64 = tokens[1];
        var content = Convert.FromBase64String(base64);

        // Upload photo to storage...
        var blobUri = await UploadImageToStorage(content);

        // Then create a Document in CosmosDb to notify our Function
        var identifier = await UploadDocument(blobUri, imageRequest.Name ?? "Bob");

        return Ok(identifier);
    }

    private async Task<Guid> UploadDocument(Uri uri, string imageName)
    {

        var endpoint = new Uri(_settings.ImageConfig.CosmosUri);
        var auth = _settings.ImageConfig.CosmosKey;
        var client = new DocumentClient(endpoint, auth);
        var identifier = Guid.NewGuid();

        await client.CreateDatabaseIfNotExistsAsync(new Database() { Id = dbName });
        await client.CreateDocumentCollectionIfNotExistsAsync(UriFactory.CreateDatabaseUri(dbName),
            new DocumentCollection { Id = colName });

        await client.CreateDocumentAsync(
            UriFactory.CreateDocumentCollectionUri(dbName, colName),
            new ImageDocument
            {
                Id = identifier,
                IsApproved = null,
                PetName = petName,
                MediaUrl = uri.ToString(),
                Created = DateTime.UtcNow
            });

        return identifier;
    }

    private async Task<Uri> UploadImageToStorage(byte[] content)
    {
        var storageName = _settings.PetsConfig.BlobName;
        var auth = _settings.PetsConfig.BlobKey;
        var uploader = new PhotoUploader(storageName, auth);
        var blob = await uploader.UploadPetPhoto(content);
        return blob.Uri;
    }