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POC# and entity framework objects
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  1. POC# and entity framework objects
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    copied!<p>try to made my first c# programme, with vs2010 and entity framework. This is the code:</p> <pre><code>public partial class Form1 : Form { ValinorEntities ve = new ValinorEntities(); public Form1() { InitializeComponent(); comboBox1.DataSource = ve.item_groups; comboBox1.DisplayMember = "item_group_name"; comboBox1.ValueMember = "item_group_id"; var departmentQuery = from d in ve.items from g in ve.item_groups where d.item_group_id_fk == g.item_group_id select new { d.item_name, g.item_group_name, d.item_id, d.item_number }; dataGridView1.DataSource = departmentQuery; dataGridView1.Columns[2].Visible = false; dataGridView1.Columns[3].Visible = false; } private void dataGridView1_CellMouseClick(object sender, DataGridViewCellMouseEventArgs e) { textBox1.Text = dataGridView1.Rows[e.RowIndex].Cells[0].Value.ToString(); textBox2.Text = dataGridView1.Rows[e.RowIndex].Cells[3].Value.ToString(); textBox3.Text = dataGridView1.Rows[e.RowIndex].Cells[2].Value.ToString(); comboBox1.DataSource = ve.item_groups; comboBox1.DisplayMember = "item_group_name"; comboBox1.ValueMember = "item_group_id"; } private void btn_New_Click(object sender, EventArgs e) { try { item item = new Valinor.item(); item.item_name = textBox1.Text; item.item_number = textBox2.Text; item.item_group_id_fk = (int)comboBox1.SelectedValue; ve.AddToitems(item); ve.SaveChanges(); MessageBox.Show("Insert successful"); } catch (Exception ex) { MessageBox.Show("Insert failed" + ex); } } private void btn_Save_Click(object sender, EventArgs e) { try { var id = Convert.ToInt32(textBox3.Text); item c = ve.items.FirstOrDefault(i =&gt; i.item_id == id); c.item_name = textBox1.Text; c.item_number = textBox2.Text; c.item_group_id_fk = (int)comboBox1.SelectedValue; ve.SaveChanges(); MessageBox.Show("Save successful"); } catch (Exception ex) { MessageBox.Show("Save failed" + ex); } } } </code></pre> <p>It's working but i have a few problem.</p> <ul> <li>What should I write a <code>comboBox1.SelectedValue</code> to the correct item is selected after clicking on a cell?</li> <li><p>In the <code>btnSave_Click</code> function the value of<code>textbox3</code> refer to ID, which is not very elegant solution. How can I object to replace it?</p></li> <li><p>If I know of such references, such as these:</p> <p><code>textBox1.Text = dataGridView1.Rows[e.RowIndex].Cells[0].Value.ToString();</code> <code>textBox2.Text = dataGridView1.Rows[e.RowIndex].Cells[3].Value.ToString();</code></p></li> </ul> <p>could be avoided somehow. To do this, however zakell that <code>dataGridView1_CellMouseClick</code> fügvénynél not refer the value of the cell but also the object. This can be to solve it?</p>
 

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