Add custom metadata to Azure blob storage files and search them with Azure Search

Date: February 1, 2018

Did you know that you can add custom metadata to your blob containers, and even to individual blob files?

You can do it in the Azure Portal, using SDK or REST API.

The most common scenario is adding metadata during file upload. Below code is uploading sample invoice from disk, and adds year, month, and day metadata properties.

const string StorageAccountName = "";
const string AccountKey = "";
const string ContainerName = "";

string ConnectionString = $"DefaultEndpointsProtocol=https;AccountName={StorageAccountName};AccountKey={AccountKey};EndpointSuffix=core.windows.net";
CloudStorageAccount storageAccount = CloudStorageAccount.Parse(ConnectionString);
CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();
CloudBlobContainer container = blobClient.GetContainerReference(ContainerName);

const string FileName = "Invoice_2017_01_01";
using (var fileStream = System.IO.File.OpenRead($@"D:\dev\BlobMetadataSample\invoices\{FileName}.pdf"))
{
    var fileNameParts = FileName.Split('_');
    var year = fileNameParts[1];
    var month = fileNameParts[2];
    var day = fileNameParts[3];

    var blob = container.GetBlockBlobReference(FileName);
    blob.Metadata.Add("year", year);
    blob.Metadata.Add("month", month);
    blob.Metadata.Add("day", day);
    blob.UploadFromStream(fileStream);

    var yearFromBlob = blob.Metadata.FirstOrDefault(x => x.Key == "year").Value;
    var monthFromBlob = blob.Metadata.FirstOrDefault(x => x.Key == "month").Value;
    var dayFromBlob = blob.Metadata.FirstOrDefault(x => x.Key == "day").Value;

    Console.WriteLine($"{blob.Name} ({yearFromBlob}-{monthFromBlob}-{dayFromBlob})");
}

If you just want to add metadata to existing blob, instead of calling blob.UploadFromStream(fileStream) you can run blob.SetMetadata().

When you create new index for blob in Azure Search, we will automatically detect these fields. If you already have Azure Search index created, you can add new fields (has to be the same as metadata key), and all changes will be synchronized with next re-indexing.

Tags: programming