Ayb4btu Ayb4btu - 3 months ago 68
C# Question

Read all values from CSV into a List using CsvHelper

So I've been reading that I shouldn't write my own CSV reader/writer, so I've been trying to use the CsvHelper library installed via nuget. The CSV file is a grey scale image, with the number of rows being the image height and the number columns the width. I would like to read the values row-wise into a single

List<string>
or
List<byte>
.

The code I have so far is:

using CsvHelper;

public static List<string> ReadInCSV(string absolutePath)
{
IEnumerable<string> allValues;

using (TextReader fileReader = File.OpenText(absolutePath))
{
var csv = new CsvReader(fileReader);
csv.Configuration.HasHeaderRecord = false;
allValues = csv.GetRecords<string>
}

return allValues.ToList<string>();
}


But
allValues.ToList<string>()
is throwing a:

CsvConfigurationException was unhandled by user code

An exception of type 'CsvHelper.Configuration.CsvConfigurationException' occurred in CsvHelper.dll but was not handled in user code

Additional information: Types that inherit IEnumerable cannot be auto mapped. Did you accidentally call GetRecord or WriteRecord which acts on a single record instead of calling GetRecords or WriteRecords which acts on a list of records?

GetRecords
is probably expecting my own custom class, but I'm just wanting the values as some primitive type or string. Also, I suspect the entire row is being converted to a single string, instead of each value being a separate string.

Answer

According to @Marc L's post you can try this:

public static List<string> ReadInCSV(string absolutePath) {
    List<string> result = new List<string>();
    string value;
    using (TextReader fileReader = File.OpenText(absolutePath)) {
        var csv = new CsvReader(fileReader);
        csv.Configuration.HasHeaderRecord = false;
        while (csv.Read()) {
           for(int i=0; csv.TryGetField<string>(i, out value); i++) {
                result.Add(value);
            }
        }
    }
    return result;
}
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