CODEWITHSUNDEEP
c#csvazure-functionsmemorystreamgzipstream
Pine Code
Pine Code

Reputation: 2787

How can I give a *.csv extension to something written in a MemoryStream?

I’m developing an Azure Function to create a CSV file from a list of custom objects, gzip it and upload it to an Azure Storage container with this code:

var blobServiceClient = new BlobServiceClient("My connection string");
var containerClient = blobServiceClient.GetBlobContainerClient("My container name");
var config = new CsvConfiguration(CultureInfo.CurrentCulture) { Delimiter = ";", Encoding = Encoding.UTF8 };

var list = new List<FakeModel>
{
   new FakeModel { Field1 = "A", Field2 = "B" },
   new FakeModel { Field1 = "C", Field2 = "D" }
};

await using var memoryStream1 = new MemoryStream();
await using var streamWriter = new StreamWriter(memoryStream1);
await using var csvWriter = new CsvWriter(streamWriter, config);

await csvWriter.WriteRecordsAsync(list);
await csvWriter.FlushAsync();

memoryStream1.Position = 0;

await using var memoryStream2 = new MemoryStream();
await using var zip = new GZipStream(memoryStream2, CompressionMode.Compress, true);
await memoryStream1.CopyToAsync(zip);

memoryStream2.Position = 0;

var blockBlob = containerClient.GetBlockBlobClient("test.csv.gz");
await blockBlob.UploadAsync(memoryStream2);

It works. When I download the gzip from the cloud to check it, obviously I get that the file has the correct name, so it’s shown as a GZ file whose name is test.csv.gz, but when I download it and open it with an extractor, I get that the CSV file inside of it is something strange, like test.csv-3, that my computer can’t open. Of course, I need it to be a valid *.csv file. The problem here is that using memory streams I can only give a name to the blob, not for the inner CSV file. How can I do it? Keep in mind that I’d like so use memory streams to keep things simple with Azure Functions’s local storage. Can you help me?

Upvotes: 0

Views: 487

Answers (1)

Jim Xu
Jim Xu

Reputation: 23141

Regarding the issue, please refer to the following code

            var blobServiceClient = new BlobServiceClient("My connection string");
            var containerClient = blobServiceClient.GetBlobContainerClient("My container name");
            var config = new CsvConfiguration(CultureInfo.CurrentCulture) { Delimiter = ";", Encoding = Encoding.UTF8 };

            var list = new List<FakeModel>
            {
               new FakeModel { Field1 = "A", Field2 = "B" },
               new FakeModel { Field1 = "C", Field2 = "D" }
            };

            await using var memoryStream1 = new MemoryStream();
            await using var streamWriter = new StreamWriter(memoryStream1);
            await using var csvWriter = new CsvWriter(streamWriter, config);

            await csvWriter.WriteRecordsAsync(list);
            await csvWriter.FlushAsync();

            memoryStream1.Position = 0;
            var options = new BlockBlobOpenWriteOptions
            {
                HttpHeaders = new BlobHttpHeaders
                {
                    ContentType = "application/gzip",
                },
            };
            await using var outStream= await containerClient.GetBlockBlobClient("test.csv.gz").OpenWriteAsync(true,options);
            await using var zip = new GZipStream(outStream, CompressionMode.Compress, true);
            
            await memoryStream1.CopyToAsync(zip);

            await using var input = await containerClient.GetBlockBlobClient("test.csv.gz").OpenReadAsync();
            await using var file = File.Create("<file path>");
            await using var zip1 = new GZipStream(input, CompressionMode.Decompress, true);
            await zip1.CopyToAsync(file);

Upvotes: 1

Related Questions