I have 500 Columns in my DataTable and I want to remove all of them except for 25 columns.
Is there any way to do this faster to save time and lines of code?
This is what I already tried:
private static void DeleteUselessColumns()
{
//This is example data!
List<DataColumn> dataColumnsToDelete = new List<DataColumn>();
DataTable bigData = new DataTable();
bigData.Columns.Add("Harry");
bigData.Columns.Add("Konstantin");
bigData.Columns.Add("George");
bigData.Columns.Add("Gabriel");
bigData.Columns.Add("Oscar");
bigData.Columns.Add("Muhammad");
bigData.Columns.Add("Emily");
bigData.Columns.Add("Olivia");
bigData.Columns.Add("Isla");
List<string> columnsToKeep = new List<string>();
columnsToKeep.Add("Isla");
columnsToKeep.Add("Oscar");
columnsToKeep.Add("Konstantin");
columnsToKeep.Add("Gabriel");
//This is the code i want to optimize------
foreach (DataColumn column in bigData.Columns)
{
bool keepColumn = false;
foreach (string s in columnsToKeep)
{
if (column.ColumnName.Equals(s))
{
keepColumn = true;
}
}
if (!keepColumn)
{
dataColumnsToDelete.Add(column);
}
}
foreach(DataColumn dataColumn in dataColumnsToDelete)
{
bigData.Columns.Remove(dataColumn);
}
//------------------------
}
var columnsToKeep = new List<string>() { "Isla", "Oscar", "Konstantin", "Gabriel"};
var toRemove = new List<DataColumn>();
foreach(DataColumn column in bigData.Columns)
{
if (!columnsToKeep.Any(name => column.ColumnName == name ))
{
toRemove.Add(column);
}
}
toRemove.ForEach(col => bigData.Columns.Remove(col));
Test1...test9 same code could be made a loop. No need to add the columns to delete in a list, just delete them in the first while loop. As for performance, not sure how to improve it.
You could try to use a DataView that selects the desired columns then copy to table. You need to experiment.
if they have different names create an array of string
var columns = new string[] { "Harry", "Konstantin","John"};
var columnsToKeep = new string[] { "John", "Konstantin"};
var columnsToDelete = from item in columns
where !columnsToKeep.Contains(item)
select item;
or using lambda
var columnsToDelete = columns
.Where (i=> !columnsToKeep.Contains(i))
.ToList();
toDelete
Harry
I have a DataGridView in a C# WinForms project in which, when the user clicks on certain DGV cells, the cell changes to a DataGridViewComboBoxCell and the ComboBox is populated with some values for the user to select. Here's the form code for the DataGridView_Click event:
private void dgvCategories_Click(Object sender, DataGridViewCellEventArgs e)
{
if (e.ColumnIndex == 5 && !(dgvCategories.Rows[e.RowIndex].Cells[e.ColumnIndex].GetType().Name == "DataGridViewComboBoxCell"))
{
// Bind combobox to dgv and than bind new values datasource to combobox
DataGridViewComboBoxCell cboNewValueList = new DataGridViewComboBoxCell();
// Get fields to build New Value query
List<string> lsNewValuesResult = new List<string>();
string strCategory = dtCategories.Rows[e.RowIndex][1].ToString();
string strCompanyName = cboSelectCompany.Text;
string strQueryGetNewValuesValidationInfo = "SELECT validationdb, validationtable, validationfield, validationfield2, validationvalue2" +
" FROM masterfiles.categories" +
" WHERE category = #category";
//" WHERE category = '" + strCategory + "'";
// Pass validation info query to db and return list of New Values
db getListOfNewValues = new db();
lsNewValuesResult = getListOfNewValues.GetNewValuesList(strQueryGetNewValuesValidationInfo, strCategory, strCompanyName);
//Populate the combobox with the list of New Values
foreach (string strListItem in lsNewValuesResult)
{
cboNewValueList.Items.Add(strListItem);
}
//
dgvCategories[e.ColumnIndex, e.RowIndex] = cboNewValueList;
}
}
Here's the code in the db class that populates the ComboBox (this likely isn't necessary to include for the purposes of this question, but for the sake of completeness, I'm including it, in case is it relevant):
public List<string> GetNewValuesList(string strValidationInfoQuery, string strCategory, string strCompanyName)
{
List<string> lsValidationInfo = new List<string>();
List<string> lsNewValuesList = new List<string>();
using (NpgsqlConnection conn = new NpgsqlConnection(connString))
using (NpgsqlCommand cmd = new NpgsqlCommand(strValidationInfoQuery, conn))
{
cmd.Parameters.AddWithValue("category", strCategory);
conn.Open();
using (NpgsqlDataReader reader = cmd.ExecuteReader())
{
while (reader.Read())
{
int intReaderIndex;
for (intReaderIndex = 0; intReaderIndex <= reader.FieldCount - 1; intReaderIndex++)
{
// reader indexes 3 & 4 correspond to categories.validationfield2 and validationvalue2, which can be null
if (string.IsNullOrEmpty(reader[intReaderIndex].ToString()))
{
lsValidationInfo.Add("");
}
else
{
lsValidationInfo.Add(reader.GetString(intReaderIndex));
}
//Console.WriteLine("reader index " + intReaderIndex + ": " + reader.GetString(intReaderIndex));
}
}
}
}
string strValidationDb = lsValidationInfo[0];
string strValidationTable = lsValidationInfo[1];
string strValidationField = lsValidationInfo[2];
string strValidationField2 = lsValidationInfo[3];
string strValidationValue2 = lsValidationInfo[4];
string strQueryGetNewValues = "SELECT DISTINCT " + strValidationField +
" FROM " + strValidationDb + "." + strValidationTable +
" WHERE company_id = (SELECT id FROM company WHERE name = '" + strCompanyName + "')";
if (!string.IsNullOrEmpty(strValidationField2) && !string.IsNullOrEmpty(strValidationValue2)) strQueryGetNewValues += " AND " + strValidationField2 + " = '" + strValidationValue2 + "'";
strQueryGetNewValues += " ORDER BY " + strValidationField;
using (NpgsqlConnection conn = new NpgsqlConnection(connString))
using (NpgsqlCommand cmd = new NpgsqlCommand(strQueryGetNewValues, conn))
{
conn.Open();
using (NpgsqlDataReader reader = cmd.ExecuteReader())
{
while (reader.Read())
{
int intReaderIndex;
for (intReaderIndex = 0; intReaderIndex <= reader.FieldCount - 1; intReaderIndex++)
{
// reader indexes 3 & 4 correspond to categories.validationfield2 and validationvalue2, which can be null
if (string.IsNullOrEmpty(reader[intReaderIndex].ToString()))
{
lsNewValuesList.Add("");
}
else
{
lsNewValuesList.Add(reader.GetString(intReaderIndex));
}
Console.WriteLine("reader index " + intReaderIndex + ": " + reader.GetString(intReaderIndex));
}
}
}
}
return lsNewValuesList;
}
The combobox is getting populated, as I can access the items in lsNewValuesResult in the _Click method. The DGV Edit Mode is set to EditOnEnter. I tried EditOnKeystroke, but that didn't cause the combobox to expand on mouse click.
This is what the combobox looks like when the cell is clicked on and the CBO is populated and added to the DGV cell:
That's after I clicked each of the two cells.
[RESOLVED]
See my Answer below.
Unfortunately solving this revealed a new issue.
I'm about to publicly admit that I'm stupid:
For design and functionality reasons that are required for this project, I am manually setting the widths and names of the DGV's columns, and I also need the 2nd through 4th columns ReadOnly = true. Well, I inadvertently set the 5th column - the column that this question is about to ReadOnly = true as well.
Thank you all for your attempts at answering. This just serves to remind us how something so simple can cause a seemingly big issue and is so easy to overlook!
If I recognize your problem correctly, in my test app i add a DataGridView whit 6 column, EditMode = EditOnEnter
(Others need three time click to open dropdown, As far as I tried) and handle CellStateChanged envent.
private void dgvCategories_CellStateChanged(object sender, DataGridViewCellStateChangedEventArgs e)
{
if (e.StateChanged == DataGridViewElementStates.Selected)
{
DataGridViewCell cell = e.Cell;
int columnIndex = cell.ColumnIndex;
int rowIndex = cell.RowIndex;
//---IF CONDITIONS--
//columnIndex == 5
// Only cells in Columns[5]
//cell.Selected
// Because this event raised two time, first for last selected cell and once again
// for currently selected cell and we need only currently selected cell.
//cell.EditType.Name != "DataGridViewComboBoxEditingControl"
// If this cell "CellStateChanged" raised for second time, only other cell types allowed
// to edit, otherwise the current cell lost last selected item.
if (columnIndex == 5 && cell.Selected && cell.EditType.Name != "DataGridViewComboBoxEditingControl")
{
DataGridViewComboBoxCell cboNewValueList = new DataGridViewComboBoxCell();
//Add items to DataGridViewComboBoxCell for test, replace it with yours.
for (int i = 0; i < 10; i++)
cboNewValueList.Items.Add($"Item {i}");
dgvCategories[columnIndex, rowIndex] = cboNewValueList;
}
}
}
NOTE: user must click two time in a cell to open drop down menu.
Edit One: As Reza Aghaei suggest for single click in cell:
private void dgvCategories_CellClick(object sender, DataGridViewCellEventArgs e)
{
DataGridViewComboBoxEditingControl editingControl = dgvCategories.EditingControl as DataGridViewComboBoxEditingControl;
if (editingControl != null)
editingControl.DroppedDown = true;
}
You might need to turn AutoGenerateColumns off:
Also, it seems to take a three clicks for the dropdown to pop.
public Form1()
{
InitializeComponent();
dataGridView1.AutoGenerateColumns = false;
dataGridView1.DataSource = GetDataSource();
DataGridViewComboBoxColumn dgvcbc = new DataGridViewComboBoxColumn();
dgvcbc.Items.Add("R0C0");
dgvcbc.Items.Add("R1C0");
dgvcbc.Items.Add("R2C0");
dgvcbc.Items.Add("R3C0");
dgvcbc.DataPropertyName = "Col0";
dataGridView1.Columns.Add(dgvcbc);
}
DataTable GetDataSource()
{
var dtb = new DataTable();
dtb.Columns.Add("Col0", typeof(string));
dtb.Columns.Add("Col1", typeof(string));
dtb.Columns.Add("Col2", typeof(string));
dtb.Columns.Add("Col3", typeof(string));
dtb.Columns.Add("Col4", typeof(string));
dtb.Rows.Add("R0C0", "R0C1", "R0C2", "R0C3", "R0C4");
dtb.Rows.Add("R1C0", "R1C1", "R1C2", "R1C3", "R1C4");
dtb.Rows.Add("R2C0", "R2C1", "R2C2", "R2C3", "R2C4");
dtb.Rows.Add("R3C0", "R3C1", "R3C2", "R3C3", "R3C4");
return dtb;
}
Are you maybe getting an error which is not being shown for some reason?
If I use your code, DataGridViewComboBoxCell seems to be populated with values, but I get DataGridViewComboBoxCell value is not valid runtime error.
This test code is working fine for me:
private void dgvCategories_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
DataGridViewComboBoxCell cboNewValueList = new DataGridViewComboBoxCell();
List<string> lsNewValuesResult = new List<string>();
lsNewValuesResult.Add("Value1");
lsNewValuesResult.Add("Value2");
lsNewValuesResult.Add("Value3");
foreach (string strListItem in lsNewValuesResult)
{
cboNewValueList.Items.Add(strListItem);
}
dgvCategories[e.ColumnIndex, e.RowIndex] = cboNewValueList;
// Added setting of initial value
cboNewValueList.Value = cboNewValueList.Items[0];
}
So maybe try setting the initial value for your DataGridViewComboBoxCell after you add it to the DataGridView.
You can consider the following facts about DataGridView:
If you set AutoGenerateColumns to false, then you need to add columns to Columns collection manually.
If you set AutoGenerateColumns to true, when you assign the data to DataSource, the control generates columns automatically for the data source. In this case, the control looks in list of columns of the data source and for each column if there's no column in the Columns collection of the control having the same DataPropertyName as data source's column name, it will add a column to Columns collection.
DataPropertyName of the datagridviews' columns determines the bound column of the data source.
You usually want to add DataGridViewXXXXColumn to columns collection rather than using a DataGridViewXXXXCell for a cell.
If you set EditMode to EditOnEnter, then if you click on dropdown button, one click is enough. If you click on cell content, two clicks is needed.
If you would like to make it single click even if you click on cell content, take a look at this post. (Note: I haven't used this is the example, it's a bit annoying.)
you can set DisplayStyle to Nothing, then it shows the column as a combo box, just in edit mode.
A basic example on using DataGridViewComboBoxColumn
I suppose you are going to show a list of Products having (Id, Name, Price, CategoryId) in a DataGridView and the CategoryId should come from a list of Categories having (Id, Name) and you are going to show CategoryId as a ComboBox.
In fact it's a basic and classic example of DataGridViewComboBoxColumn:
private void Form1_Load(object sender, EventArgs e) {
var categories = GetCategories();
var products = GetProducts();
var idColumn = new DataGridViewTextBoxColumn() {
Name = "Id", HeaderText = "Id", DataPropertyName = "Id"
};
var nameColumn = new DataGridViewTextBoxColumn() {
Name = "Name", HeaderText = "Name", DataPropertyName = "Name"
};
var priceColumn = new DataGridViewTextBoxColumn() {
Name = "Price", HeaderText = "Price", DataPropertyName = "Price"
};
var categoryIdColumn = new DataGridViewComboBoxColumn() {
Name = "CategoryId", HeaderText = "Category Id", DataPropertyName = "CategoryId",
DataSource = categories, DisplayMember = "Name", ValueMember = "Id",
DisplayStyle = DataGridViewComboBoxDisplayStyle.Nothing
};
dataGridView1.Columns.AddRange(idColumn, nameColumn, priceColumn, categoryIdColumn);
dataGridView1.EditMode = DataGridViewEditMode.EditOnEnter;
dataGridView1.AutoGenerateColumns = false;
dataGridView1.DataSource = products;
}
public DataTable GetProducts() {
var products = new DataTable();
products.Columns.Add("Id", typeof(int));
products.Columns.Add("Name", typeof(string));
products.Columns.Add("Price", typeof(int));
products.Columns.Add("CategoryId", typeof(int));
products.Rows.Add(1, "Product 1", 100, 1);
products.Rows.Add(2, "Product 2", 200, 2);
return products;
}
public DataTable GetCategories() {
var categories = new DataTable();
categories.Columns.Add("Id", typeof(int));
categories.Columns.Add("Name", typeof(string));
categories.Rows.Add(1, "Category 1");
categories.Rows.Add(2, "Category 2");
return categories;
}
Learn more
To learn more about DataGridView, take a look at DataGridView Control (Windows Forms). It contains links to some documentations and useful How To articles, including:
DataGridView Control Overview
Basic Column, Row, and Cell Features in the Windows Forms DataGridView Control
Basic Formatting and Styling in the Windows Forms DataGridView Control
Column Types in the Windows Forms DataGridView Control
I have been able to make one existing column combo box column in the datagridview, how do I do it for several columns? Also how do I add existing distinct records in the combobox items? The user will be able to either choose value from combobox item or write their own. So far my code is:
dgvLoadTable.DataSource = null;
var context = new CadAdminEntities();
var TableName = cboSelectTable.Text.ToString();
var rawData = context.GetType().GetProperty(TableName).GetValue(context, null);
var truncatedData = ((IQueryable<object>)rawData).Take(0);
var source = new BindingSource { DataSource = truncatedData };
dgvLoadTable.DataSource = source;
dgvLoadTable.ReadOnly = false;
dgvLoadTable.AllowUserToAddRows = true;
DataGridViewComboBoxCell dgvCol = new DataGridViewComboBoxCell();
for (int row= 0; row < dgvLoadTable.Rows.Count; row++)
{
for (int col = 0; col < dgvLoadTable.Columns.Count; col++)
{
if(col==2||col==4)
this.dgvLoadTable[col,row] = dgvCol;
//This part throws error, as there is only one combobox
}
}
dgvLoadTable.Refresh();
This is easy to fix:
this.dgvLoadTable[col, row] = new DataGridViewComboBoxCell();
will create a fresh ComboBoxCell for each case.
You can delete the line
DataGridViewComboBoxCell dgvCol = new DataGridViewComboBoxCell();
Note that since you have a Databound DGV and the Columns were probably created automatically, you should keep in mind, that often one needs to switch off that automatism and create all column manually before setting the DataSource..
Is it possible to add new cell base on column name? How can I possibly do this?
As of now here is my code
foreach (var c in br)
{
dataGridView1.Columns.Add(new DataGridViewTextBoxColumn() { HeaderText = c.AccountCode });
foreach (var r in c.TBal)
{
//add new cell base on c.AccountCode
}
}
My br has this data
Any ideas? thanks :)
What I want to happen is that AccountCode should be column and TBal balance should its data under it and so on..
I'm trying to guess here what you want.
You could probably add the Name property for the column name aside from HeaderText property and use that column name identity to populate the cells.
{ HeaderText = c.AccountCode, Name = "colAccountCode" }
So, let's just say you are using the name colAccountCode as your column name for this new column. So, you will have this code that would probably look like this;
foreach (var c in br)
{
dataGridView1.Columns.Add(new DataGridViewTextBoxColumn() { HeaderText = c.AccountCode, Name = "colAccountCode" });
int rows = dataGridView1.Rows.Count, rowCtr = 0;
if (rows>0) // Make sure there are rows in DataGridView
{
foreach (var r in c.TBal)
{
if (rowCtr < rows) // Make sure that rowCtr is less than Total Rows since index always starts with zero
{
dataGridView1.Rows[rowCtr++].Cells["colAccountCode"].Value = r;
}
}
}
}
Here is my code:
DataSet data = new DataSet();
data.ReadXml("data.xml");
DataGridView grid = new DataGridView();
var genreCboBoxItems = data.Tables[0].AsEnumerable().Select(genre => genre.Field<string>("genre")).Distinct().ToArray();
// TODO: Make is so the 'genre' column in grid is a combo box?
grid.DataSource = data.Tables[0];
grid.Dock = DockStyle.Fill;
this.Controls.Add(grid);
*edit: genreCboBoxItems
Try this: (not tested)
var column = new DataGridViewComboBoxColumn();
column.DataSource = data.Tables[0].AsEnumerable().
Select(genre => new { genre = genre.Field<string>("genre") }).Distinct();
column.DataPropertyName = "genre";
column.DisplayMember = "genre";
column.ValueMember = "genre";
grid.DataSource = data.Tables[0];
// Instead of the below line, You could use grid.Columns["genre"].Visible = false;
grid.Columns.Remove("genre");
grid.Columns.Add(column);
This might help you cast DataGridViewColumn to DataGridViewComboBox.
First create DataGridViewComboBoxColumn using designer with proper name. Then say you have a list of String list and other string values to bind to that datagridview then use this code:
Below code will bind a list to two DataGridViewTextBoxCell and a DataGridViewComboBoxCell. Note AllCriterias is a list with two string values and a list of string. DGVEligibilityCriteria is the grid name.
for (int i = 0; i < AllCriterias.Count; i++)
{
DataGridViewTextBoxCell Cmb1 = (DataGridViewTextBoxCell)DGVEligibilityCriteria.Rows[i].Cells[0];
Cmb1.Value = AllCriterias[i].Name;
DataGridViewTextBoxCell Cmb2 = (DataGridViewTextBoxCell)DGVEligibilityCriteria.Rows[i].Cells[1];
Cmb2.Value = AllCriterias[i].Type;
DataGridViewComboBoxCell Cmb = (DataGridViewComboBoxCell)DGVEligibilityCriteria.Rows[i].Cells[2];
foreach (var filtervalue in AllCriterias[i].FilterValues)
{
Cmb.Items.Add(filtervalue);
}
}
Need to display the fist index as default by setting selectindex property.
Use this code : Here "filterValues" is the name of the DataGridViewComboBoxCell which u created in the datagridview designer.
foreach (DataGridViewRow row in DGVEligibilityCriteria.Rows)
{
row.Cells["filterValues"].Value = (row.Cells["filterValues"] as DataGridViewComboBoxCell).Items[0];
}