CsvHelper - read in multiple columns to a single list
Version 3 has support for reading and writing IEnumerable
properties. You can use an IList<T>
property just like you have. You just need to specify the start index of the field.
Map( m => m.Attributes ).Index( 2 );
I don't know this library, so following might be helpful or not.
If you already have an IEnumerable<IEnumerable<string>>
which represents all records with all columns you could use this Linq query to get your List<Person>
with the IList<string> Attributes
:
IEnumerable<IEnumerable<string>> allRecords = .....;
IEnumerable<Person> allPersons = allRecords
.Select(rec =>
{
var person = new Person();
person.FirstName = rec.ElementAt(0);
person.LastName = rec.ElementAtOrDefault(1);
person.Attributes = rec.Skip(2).ToList();
return person;
}).ToList();
Edit: Downloaded the library, following at least compiles, could not really test it:
IList<Person> allPersons = new List<Person>();
using (var reader = new CsvHelper.CsvReader(yourTextReader))
{
while (reader.Read())
{
var person = new Person();
person.FirstName = reader.CurrentRecord.ElementAt(0);
person.LastName = reader.CurrentRecord.ElementAtOrDefault(1);
person.Attributes = reader.CurrentRecord.Skip(2).ToList();
allPersons.Add(person);
}
}
You don't actually need to define the column names beforehand, you can get them from the FieldHeaders
property. So in a more dynamic version of Neil's answer you could define your Mapper
as such:
public sealed class PersonMap : CsvClassMap<Person> {
public override void CreateMap() {
Map(m => m.FirstName).Name("FirstName").Index(0);
Map(m => m.LastName).Name("LastName").Index(1);
Map(m => m.Attributes).ConvertUsing(row =>
(row as CsvReader)?.FieldHeaders
.Where(header => header.StartsWith("Attribute"))
.Select(header => row.GetField<string>(header))
.Where(value => !string.IsNullOrWhiteSpace(value))
.ToList()
);
}
}
This does the trick as a mapper.
public sealed class PersonMap : CsvClassMap<Person>
{
private List<string> attributeColumns =
new List<string> { "Attribute1", "Attribute2", "Attribute3" };
public override void CreateMap()
{
Map(m => m.FirstName).Name("FirstName").Index(0);
Map(m => m.LastName).Name("LastName").Index(1);
Map(m => m.Attributes).ConvertUsing(row =>
attributeColumns
.Select(column => row.GetField<string>(column))
.Where(value => String.IsNullOrWhiteSpace(value) == false)
);
}
}
Then you just need something like this
using (var reader = new CsvReader(new StreamReader(filePath)))
{
reader.Configuration.RegisterClassMap<PersonMap>();
while (reader.Read())
{
var card = reader.GetRecord<Person>();
}
}