删除DataGridView和数据库中的行

Question

I'm completely new to databases and EF but I made a database with EF and have a DataGridView control on a windows form that I made by dragging my datasource to my form. After the user enters their information and hits the save button it succesfully saves their information in the database using this code

public partial class bsMainPage : Form
{
    BSDATAContainer db = new BSDATAContainer();
    public bsMainPage()
    {
        InitializeComponent();
    }

    private void saveBtn_Click(object sender, EventArgs e)
    {
        BSRecords breakfastRecord = new BSRecords();
        breakfastRecord.BS = brkBS.ToString();
        breakfastRecord.Carbs = brkCarb.ToString();
        breakfastRecord.Notes = brkftNoteTxt.Text;
        breakfastRecord.Date = dateTxt.Text;
        BSRecords lunchRecord = new BSRecords();
        lunchRecord.BS = lchBS.ToString();
        lunchRecord.Carbs = lchCarb.ToString();
        lunchRecord.Notes = lnchNoteTxt.Text;
        lunchRecord.Date = dateTxt.Text;
        BSRecords dinnerRecord = new BSRecords();
        dinnerRecord.BS = dnrBS.ToString();
        dinnerRecord.Carbs = dnrCarb.ToString();
        dinnerRecord.Notes = dnnrNoteTxt.Text;
        dinnerRecord.Date = dateTxt.Text;
        db.BSRecords.Add(breakfastRecord);
        db.BSRecords.Add(lunchRecord);
        db.BSRecords.Add(dinnerRecord);
        db.SaveChanges();
   }
}

But it doesn't show up in the database until I restart the program. When the user selects a row in the DataGridView and hits the delete button which has this code

private void deleteRowsBtn_Click(object sender, EventArgs e)
{
    foreach (DataGridViewRow item in this.bSRecordsDataGridView.SelectedRows)
    {
        bSRecordsDataGridView.Rows.RemoveAt(item.Index);
    }
    db.SaveChanges();
}

It deletes the data in the DataGridView but doesn't save the changes in my database. I have followed all the answers I found on here and other sites to delete in the database but nothing will save the deleted changes. Does anyone have any idea how to make it work?

Answer 1

You can delete it using remove. You will need to get the key/id field so without seeing the grid and assuming it is say in a hidden first column:

private void deleteRowsBtn_Click(object sender, EventArgs e)
{
    string delId;
    BSRecords deleteRecord;
    foreach (DataGridViewRow item in this.bSRecordsDataGridView.SelectedRows)
    {
        bSRecordsDataGridView.Rows.RemoveAt(item.Index);

        // code to remove record from database
        delId = item.Cells[0].Value.ToString();  // column that has id field
        deleteRecord = db.BSRecords.First(b => b.Id == delId);    // get the record. will throw exception if not found.
        db.BSRecords.Remove(deleteRecord);

    }
    db.SaveChanges();
    bSRecordsDataGridView.DataBind();   // this will refresh your grid. Do same in save.
}

Also note you can rewrite this code:

BSRecords breakfastRecord = new BSRecords();
breakfastRecord.BS = brkBS.ToString();
breakfastRecord.Carbs = brkCarb.ToString();
breakfastRecord.Notes = brkftNoteTxt.Text;
breakfastRecord.Date = dateTxt.Text;

with an object initializer:

BSRecords breakfastRecord = new BSRecords { BS = brkBS.ToString(), 
                                            Carbs = brkCarb.ToString(),
                                            Notes = brkftNoteTxt.Text, 
                                            Date = dateTxt.Text };