How do I change the csv header, C#

Question

I’m generating a CSV file, but I’d like the header was the same as anottation displayname. When I export, the displayname is ignored.

call of the method

string csv = ListToCSV(resultado);
private string ListToCSV<T>(IEnumerable<T> list)
        {
            System.Text.StringBuilder sList = new System.Text.StringBuilder();

            Type type = typeof(T);
            var props = type.GetProperties();
            sList.Append(string.Join(";", props.Select(p => p.Name)));            

            sList.Append(Environment.NewLine);

            foreach (var element in list)
            {
                sList.Append(string.Join(";", props.Select(p => p.GetValue(element, null))));
                sList.Append(Environment.NewLine);
            }

            return sList.ToString();
        }

File(new System.Text.UTF8Encoding().GetBytes(csv), "text/csv", "consulta.csv");

Answer 1

First of all, I would like to remind you that mounting a CSV correctly is not as simple as it seems, so I advise you to use the CsvHelper

as for Displayname, you can check if Property has this attribute using the method PropertyIjnfo.GetCustomAttribute<T>. Follow an example.:

public class Exemplo
{
    [Display(Name = "Property 01")]
    public string Prop1 { get; set; }
    [Display(Name = "Property 02")]
    public string Prop2 { get; set; }
    [Display(Name = "Property 02")]
    public string Prop3 { get; set; }
}

var props = typeof(Exemplo).GetProperties().Select(prop => {
    var display = prop.GetCustomAttribute<DisplayAttribute>();
    if (display != null)
        return display.Name;
    return prop.Name;
});
Console.WriteLine(String.Join(", ", props));

Depending on your version of . NET, you may need to make use of the method PropertyInfo.GetCustomAttributes

var props = typeof(Exemplo).GetProperties().Select(prop => {
    var attributes = prop.GetCustomAttributes(typeof(DisplayAttribute), false);
    if (attributes != null && attributes.Length > 0) {
        var display = attributes[0] as DisplayAttribute;
        return display.Name;
    }   
    return prop.Name
});
Console.WriteLine(String.Join(", ", props));

Follow the example using the CsvHelper.:

public class Exemplo
{
    [Display(Name = "Property 01")]
    public Guid Prop1 { get; set; }
    [Display(Name = "Property 02")]
    public Guid Prop2 { get; set; }
    [Display(Name = "Property 03")]
    public Guid Prop3 { get; set; }
}

public class ExemploMap : ClassMap<Exemplo>
{
    public ExemploMap()
    {
        var type = typeof(Exemplo);
        var props = type.GetProperties();
        foreach (var prop in props)
        {
            var display = prop.GetCustomAttribute<DisplayAttribute>();
            Map(type, prop).Name(display?.Name ?? prop.Name);
        }
    }
}

var itens = Enumerable.Range(0, 11).Select(i => new Exemplo
{
    Prop1 = Guid.NewGuid(),
    Prop2 = Guid.NewGuid(),
    Prop3 = Guid.NewGuid(),
});
using (var stream = new MemoryStream())
{
    using (var writer = new StreamWriter(stream, Encoding.UTF8, Int16.MaxValue, true))
    {
        var csvWriter = new CsvHelper.CsvWriter(writer);
        csvWriter.Configuration.RegisterClassMap<ExemploMap>();
        csvWriter.Configuration.Delimiter = ";";
        csvWriter.WriteRecords(itens);
        csvWriter.Flush();
    }

    File(stream, "text/csv", "consulta.csv")
}