This has been addressed earlier but I am getting the error again - "No header record found” on reading a csv stream"

[ankku]

Below is the method i am trying to read a stream and I am getting the error as No header record found. I have checked the stream and its return length of stream. and also to verify that my stream is valid I checked with writing it in StreamReader and then using readtoEnd() and it gives me all contents. Now I cant do readToEnd() for large files so going for Stream. below is the method How I am reading blobs and passing stream. I am using the CSVHelper version 15 here

 public Type DataType
        {
            get
            {
                switch( Type.ToUpper() )
                {
                    case "STRING":
                        return typeof(string);

                    case "INT":
                        return typeof( int );

                    case "BOOL":
```
                    case "BOOLEAN":
                        return typeof( bool );

                    case "FLOAT":
                    case "SINGLE":
                    case "DOUBLE":
                        return typeof( double );

                    case "DATETIME":
                        return typeof( DateTime );

                    default:
                        throw new NotSupportedException( $"CSVColumn data type '{Type}' not supported" );
                }
            }
        }
// This is the method where the stream is passed and the error is received at line "csv.ReadHeader()"
```
private IEnumerable<Dictionary<string, EntityProperty>> ReadCSV(Stream source, IEnumerable<TableField> cols)          

{              
         using (TextReader reader = new StreamReader(source, Encoding.UTF8))
                {
               
                    var cache = new TypeConverterCache();
                    cache.AddConverter<float>(new CSVSingleConverter());
                    cache.AddConverter<double>(new CSVDoubleConverter());
                    var csv = new CsvReader(reader,
                        new CsvHelper.Configuration.CsvConfiguration(global::System.Globalization.CultureInfo.InvariantCulture)
                        {
                            Delimiter = ";",
                            HasHeaderRecord = true,
                            CultureInfo = global::System.Globalization.CultureInfo.InvariantCulture,
                            TypeConverterCache = cache
                        });
                    csv.Read();
                    csv.ReadHeader();


                    var map = (
                            from col in cols
                            from src in col.Sources()
                            let index = csv.GetFieldIndex(src, isTryGet: true)
                            where index != -1
                            select new { col.Name, Index = index, Type = col.DataType }).ToList();

                    while (csv.Read())
                    {
                        yield return map.ToDictionary(
                            col => col.Name,
                            col => EntityProperty.CreateEntityPropertyFromObject(csv.GetField(col.Type, col.Index)));
                    }
               
                }
```
// This is the method from where the stream is being returned to ReadCsv() method above
```
public async Task<Stream> ReadStream(string containerName, string digestFileName, string fileName, string connectionString)
        {
            string data = string.Empty;
            string fileExtension = Path.GetExtension(fileName);
            var contents = await DownloadBlob(containerName, digestFileName, connectionString);              
               
           
            return contents;
        }

// method where blob is read as stream
 public async Task<Stream> DownloadBlob(string containerName, string fileName, string connectionString)
        {
           
            Microsoft.Azure.Storage.CloudStorageAccount storageAccount = Microsoft.Azure.Storage.CloudStorageAccount.Parse(connectionString);
            CloudBlobClient serviceClient = storageAccount.CreateCloudBlobClient();
            CloudBlobContainer container = serviceClient.GetContainerReference(containerName);
            CloudBlockBlob blob = container.GetBlockBlobReference(fileName);
            if (!blob.Exists())
            {
                throw new Exception($"Unable to upload data in table store for document");
            }
           
            return await blob.OpenReadAsync();
           
        }`
```

[JoshClose]

Read returns a bool. If that bool is false, meaning there is no more data, you'll get that error when calling ReadHeader because there is no header record. Basically it's an empty file.

I can't think of any other reason this would happen.