Using CSVHelper on file upload

问题

I am trying to use the CSVhelper plugin to read an uploaded CSV file. Here is my modelBinder class:

public class SurveyEmailListModelsModelBinder : DefaultModelBinder
{
    public override object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
    {
        var csv = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);
        var file = ((csv.RawValue as HttpPostedFileBase[]) ?? Enumerable.Empty<HttpPostedFileBase>()).FirstOrDefault();

        if (file == null || file.ContentLength < 1)
        {
            bindingContext.ModelState.AddModelError(
                "",
                "Please select a valid CSV file"
            );
            return null;
        }

        using (var reader = new StreamReader(file.InputStream))
        using (var csvReader = new CsvReader(reader))
        {
            return csvReader.GetRecords<SurveyEmailListModels>().ToArray();
        }
    }
}

These are the objects I am trying to map to:

public class SurveyEmailListModels
{
    [Key]
    [CsvField(Ignore = true)]
    public int SurveyEmailListId { get; set; }

    [CsvField(Index = 0)]
    public int ProgramId { get; set; }

    [CsvField(Index = 1)]
    public virtual SurveyProgramModels SurveyProgramModels { get; set; }

    [CsvField(Index = 2)]
    public string SurveyEmailAddress { get; set; }

    [CsvField(Index = 3)]
    public bool SurveyResponded { get; set; }

}

Inside the Visual Studio debugger I am getting an error:

base {"You must call read on the reader before accessing its data."} CsvHelper.CsvHelperException {CsvHelper.CsvReaderException}

回答1:

Not used the plugin but the error message seems pretty clear. There must be a Read() function to call before accessing the results. Try changing your code to something like this:

using (var reader = new StreamReader(file.InputStream))
using (var csvReader = new CsvReader(reader))
{
    // Use While(csvReader.Read()); if you want to read all the rows in the records)
    csvReader.Read();
    return csvReader.GetRecords<SurveyEmailListModels>().ToArray();
}

来源：https://stackoverflow.com/questions/11086942/using-csvhelper-on-file-upload

标签

asp.net-mvc-3

csv

csvhelper