dmdb/view/frmExportCsv.cs

using System;
using System.Collections.Generic;
using System.Reflection;
using System.Windows.Forms;
using dezentrale.model;

namespace dezentrale.view
{
    public class frmExportCsv<T> : FormWithActionButtons
    {
        private List<T> entities;
        private LvSelectFields lv;

        public List<string> SelectedProperties { get; set; } = new List<string>();

        private bool ExportCsv()
        {
            SaveFileDialog sfd = new SaveFileDialog(){
                FileName = $"{typeof(T)}_{entities.Count}_items.csv",
                Filter = "Comma-Separated-Value files (*.csv)|*.csv"
            };
            DialogResult dr = sfd.ShowDialog();
            if (dr != DialogResult.OK)
                return false;

            try
            {
                CsvFile csv = new CsvFile() {

                };

                //Build headline
                csv.FileContents.Add(SelectedProperties);

                foreach (T t in entities)
                {
                    List<string> t_csv = new List<string>();
                    foreach (string p in SelectedProperties)
                    {
                        //Get propertyinfo from T
                        PropertyInfo pi = typeof(T).GetProperty(p);
                        if (!pi.CanRead) continue;
                        try
                        {
                            object o = pi.GetValue(t, null);
                            string propVal = (o == null ? "null" : o.ToString());
                            t_csv.Add(propVal);
                        } catch(Exception ex)
                        {
                            t_csv.Add(ex.Message);
                        }
                    }
                    csv.FileContents.Add(t_csv);
                }
                csv.SaveFile(sfd.FileName);
            } catch(Exception ex)
            {
                MessageBox.Show($"Error({ex.GetType()}):\r\n{ex.Message}");
                return false;
            }
            return true;
        }


        private void FormLoad(object sender, System.EventArgs e)
        {
            this.Text = $"Export {entities.Count} entities of type \"{typeof(T).ToString()}\"";

            this.Controls.Add(lv = new LvSelectFields()
            {
                Left = 0,
                Width = this.ClientSize.Width,
                Top = 0,
                Height = this.ClientSize.Height - 60,
                Anchor = AnchorStyles.Top | AnchorStyles.Left | AnchorStyles.Bottom | AnchorStyles.Right,
            });

            foreach (var p in typeof(T).GetProperties())
            {
                lv.AddEntry(p.Name);
            }

            List<string> failToSelect = new List<string>();
            foreach(string s in SelectedProperties)
            {
                if (!lv.ItemSelection(s, true)) {
                    failToSelect.Add(s);
                }
            }
            foreach (string s in failToSelect) {
                SelectedProperties.Remove(s);
            }

            this.AddButton("All fields", (se, ev) => {
                SelectedProperties = lv.GetAllItems();
                if (ExportCsv()) this.Close();
            });
            this.AddButton("Selected fields", (se, ev) => {
                SelectedProperties = lv.GetSelectedItems();
                if (ExportCsv()) this.Close();
            });
            this.AddButton("Cancel", (se, ev) => { this.Close(); });
        }

        public frmExportCsv(T t)
        {
            entities = new List<T> { t };
            this.Load += FormLoad;
        }
        public frmExportCsv(List<T> l)
        {
            entities = l;
            this.Load += FormLoad;
        }
    }
}