Is there an example of Enqueue() to read/load a file using CSVHelper?

question
,
1

I wondered if anyone has tried to Enqueue a job that uses CSVHelper to load a file into a SQL Server database. I am just looking for example code to use as a template for my app. I have read through all of the Hangfire documentation on docs.hangfire.io and am still learning to use this great tool.

My code that will be Enqueued looks something like this:

       using (var reader = new StreamReader(model.ImportFile.OpenReadStream()))
       using (var csv = new CsvReader(reader))
        {
            csv.Configuration.HeaderValidated = null;
            csv.Configuration.MissingFieldFound = null;
            var record = new MyModel();
            var records = csv.EnumerateRecords(record);
            int recordCount = 0;
            foreach (var csvRecord in records)
            { ...
               await _dbContext.TableName.AddAsync(MyModel);
               await _dbContext.SaveChangesAsync();
            }

Thanks!

2

By the way, this is a ASP.NET Core 3.0 MVC web app.

The main question I have is do I need to define and instantiate my interfaces and services again in the enqueued method, or does the background job inherit those definitions from the Controller class it’s being enqueued from?

3

First attempt at just Enqueuing it and I got this error:

Newtonsoft.Json.JsonSerializationException: Error setting value to ‘ContentDisposition’ on ‘Microsoft.AspNetCore.Http.FormFile’.
—> System.NullReferenceException: Object reference not set to an instance of an object.
at Microsoft.AspNetCore.Http.FormFile.set_ContentDisposition(String value)
at Newtonsoft.Json.Serialization.ExpressionValueProvider.SetValue(Object target, Object value)
— End of inner exception stack trace —

I think I have to pass something into the method or define something in the method, but not sure what.

4

It seems like you can’t pass in an IFormFile object to an Enqueued task because it cannot be serialized? Is that true, or do I have to do something in my method to allow the background task to work with IFormFile?

Here’s my method:

   public async Task ImportAsync(IFormFile importFile, int userId)

This same question has been asked before but not answered:
http://hangfire.discourse.group/t/interface-or-abstract-class-and-cannot-be-instantiated/5442