Winforms将文本文件加载到datagridview并在组合框中设置默认值

Question

I have my problem in my datagrid view.

The datagridview is from the text file:

Student Name|Grade Level|Student Number|Gender

John,Grade 7,54015, 1

Jessy,Grade 3,20147, 2

Kyle,Grade 9,41812, 1

Howard,Grade 6,8436, 1

And my code:

        var lines = File.ReadAllLines(@"C:\Users\1\Desktop\1.txt");
        if (lines.Count() > 0)
        {
            foreach (var columnName in lines.FirstOrDefault()
                .Split(new[] { '|' }, StringSplitOptions.RemoveEmptyEntries))
            {
                dataGridView1.Columns.Add(columnName, columnName);
            }
            foreach (var cellValues in lines.Skip(1))
            {
                var cellArray = cellValues
                    .Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
                if (cellArray.Length == dataGridView1.Columns.Count)
                    dataGridView1.Rows.Add(cellArray);
            }
            foreach (var columnName in lines.First()
         .Split(new[] { '|' }, StringSplitOptions.RemoveEmptyEntries))
            {
                if (columnName == "Gender")
                {
                    var dgc = new DataGridViewComboBoxColumn() { Name = "hi", HeaderText = "bye" };
                    // dgc.Items.AddRange("Male", "Female");


                    DataTable dt = new DataTable();
                    DataColumn dc1 = new DataColumn("ID");
                    DataColumn dc2 = new DataColumn("Name");
                    dt.Columns.Add(dc1);
                    dt.Columns.Add(dc2);
                    dt.Rows.Add(1, "Male");
                    dt.Rows.Add(2, "Female");


                    DataGridViewComboBoxColumn c1 = new DataGridViewComboBoxColumn();
                    c1.DataSource = dt;
                    c1.DisplayMember = "Name";
                    c1.ValueMember = "ID";


                    for (int i = 0; i < dt.Rows.Count; i++)
                    {
                        if (dt.Rows[i]["ID"].ToString() == "1") // 1 for MALE & 2 for FEMALE
                        {
                            c1.DefaultCellStyle.NullValue = dt.Rows[i]["Name"];
                        }

                    }
                    dataGridView1.Columns.Add(c1);
                    continue;
                }

            }
        }

What i want is to remove the 3rd column and replace it by the fourth column and also to change the value of this

if (dt.Rows[i]["ID"].ToString() == " 1 ") // 1 for MALE & 2 for FEMALE on value member ID

to the fourth value of a line in the text file.

John,Grade 7,54015, 1

Jessy,Grade 3,20147, 2

Kyle,Grade 9,41812, 1

Howard,Grade 6,8436, 1

If the value is 1, the default value of combobox is male. While, if the value 2, the default value of combobox is female. Can anyone fix and edit my code?

Thanks to everyone!

Answer 1

Try changing your first loop to handle the "gender" column differently than the rest.

Create a ComboBox column and populate it with the two gender values.

foreach (var columnName in lines.First()
             .Split(new[] { '|' }, StringSplitOptions.RemoveEmptyEntries))
{
    if (columnName == "Gender")
    {
        var dgc = new DataGridViewComboBoxColumn() { HeaderText = "Gender" };
        dgc.Items.AddRange(
            new KeyValuePair<string, string>("1", "Male"),
            new KeyValuePair<string, string>("2", "Female"));
        dgc.ValueMember = "Key";
        dgc.DisplayMember = "Value";

        dataGridView1.Columns.Add(dgc);
        continue;
    }

    dataGridView1.Columns.Add(columnName, columnName);
}

Then when you add your rows of data, including the gender, it should display correctly in the ComboBox but also allow you to change the value.

---

Edit (update for setting a default value in the ComboBox):

foreach (var cellValues in lines.Skip(1))
{
    var cellArray = cellValues.Split(new[] { ',' });

    if (cellArray.Length == dataGridView1.Columns.Count)
    {
        if (String.IsNullOrEmpty(cellArray[dataGridView1.Columns.Count]))
            cellArray[dataGridView1.Columns.Count] = "1";

        dataGridView1.Rows.Add(cellArray);
    }
}

Basically, the above just looks at the last "column" from the file and, if it's empty, then default to "Male".

I also removed StringSplitOptions.RemoveEmptyEntries . That option will only return 3 elements in cellArray when the gender column is empty, which will also cause cellArray.Length == dataGridView1.Columns.Count to fail.

Answer 2

This works,

        DataTable dt = new DataTable();
        dt.Columns.Add("ID");
        dt.Columns.Add("Name");
        dt.Rows.Add(1, "Male");
        dt.Rows.Add(2, "Female");

        var lines = File.ReadAllLines(@"C:\Users\1\Desktop\1.txt");
        if (lines.Count() > 0)
        {
            foreach (var columnName in lines.FirstOrDefault()
                .Split(new[] { '|' }, StringSplitOptions.RemoveEmptyEntries))
            {
                if (columnName == "Gender")
                {
                    var c1 = new DataGridViewComboBoxColumn();
                    c1.DataSource = dt;
                    c1.DisplayMember = "Name";
                    c1.ValueMember = "ID";
                    c1.HeaderText = "Gender";

                    dataGridView1.Columns.Add(c1);
                    continue;
                }
                dataGridView1.Columns.Add(columnName, columnName);
            }
            foreach (var cellValues in lines.Skip(1))
            {
                var cellArray = cellValues
                    .Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
                if (cellArray.Length == dataGridView1.Columns.Count)
                    dataGridView1.Rows.Add(cellArray);
            }
        }

I also like to point out that you are using

cellValues.Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries);

which could be dangerous, because of StringSplitOptions.RemoveEmptyEntries the entry

Hulk,,8436,1

would be skipped.

And I would suggest you use a DataTable as a DataSource

    private void Form1_Shown(object sender, EventArgs e)
    {


        DataTable dt = new DataTable();
        dt.Columns.Add("ID");
        dt.Columns.Add("Name");
        dt.Rows.Add(1, "Male");
        dt.Rows.Add(2, "Female");

        var table = GetDataTable(@"C:\temp\1.txt");
        foreach (DataColumn column in table.Columns)
        {
            var columnName = column.ColumnName;
            DataGridViewColumn col;
            if (columnName == "Gender")
            {
                var c1 = new DataGridViewComboBoxColumn();
                c1.DataSource = dt;
                c1.DisplayMember = "Name";
                c1.ValueMember = "ID";
                col = c1;
            }
            else
            {
                col = new DataGridViewTextBoxColumn();
            }
            col.HeaderText = "Gender";
            col.DataPropertyName = columnName;
            dataGridView1.Columns.Add(col);

        }
        dataGridView1.DataSource = table;
    }

the method could look like this

    private DataTable GetDataTable(string fileName)
    {
        var table = new DataTable();
        var lines = File.ReadAllLines(@"C:\temp\1.txt");
        if (lines.Count() > 0)
        {
            foreach (var columnName in lines.FirstOrDefault()
                .Split(new[] { '|' }, StringSplitOptions.RemoveEmptyEntries))
            {
                table.Columns.Add(columnName);
            }
            foreach (var cellValues in lines.Skip(1))
            {
                var cellArray = cellValues
                    .Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
                if (cellArray.Length == table.Columns.Count)
                    table.Rows.Add(cellArray);
            }
        }
        return table;
    }

Answer 3

Do something like this,

 public partial class Form1 : Form
    {
        bool bIsComboBox = false;
        delegate void SetComboBoxCellType(int iRowIndex);
        DataTable dt = new DataTable();
        public Form1()
        {
            InitializeComponent();

            var lines = File.ReadAllLines(@"C:\\1.txt");
            if (lines.Count() > 0)
            {
                foreach (var columnName in lines.FirstOrDefault()
                    .Split(new[] { '|' }, StringSplitOptions.RemoveEmptyEntries))
                {
                    dt.Columns.Add(columnName, typeof(string));
                }
                foreach (var cellValues in lines.Skip(1))
                {
                    var cellArray = cellValues
                        .Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
                  //  if (cellArray.Length == dataGridView1.Columns.Count)
                        dt.Rows.Add(cellArray);
                }
                dataGridView1.DataSource = dt;

            }

        }


        private void dataGridView1_CellEnter(object sender, DataGridViewCellEventArgs e)
        {
            SetComboBoxCellType objChangeCellType = new SetComboBoxCellType(ChangeCellToComboBox);

            if (e.ColumnIndex == this.dataGridView1.Columns["Gender"].Index)
            {
                this.dataGridView1.BeginInvoke(objChangeCellType, e.RowIndex);
                bIsComboBox = false;
            }
        }
        private void ChangeCellToComboBox(int iRowIndex)
        {
            if (bIsComboBox == false)
            {
                DataGridViewComboBoxCell dgComboCell = new DataGridViewComboBoxCell();
                dgComboCell.DisplayStyle = DataGridViewComboBoxDisplayStyle.Nothing;


                dgComboCell.DataSource = dt;
                dgComboCell.ValueMember = "Gender";
                dgComboCell.DisplayMember = "Gender";

                dataGridView1.Rows[iRowIndex].Cells[dataGridView1.CurrentCell.ColumnIndex] = dgComboCell;
                bIsComboBox = true;
            }
        }