I have a ComboBox which gets Text and Value fields from a DataTable object.
foreach (DataRow dr in dtSip.Rows)
{
cbxSipNo.Items.Add(new { Text = dr[0].ToString() ,Value = dr[2].ToString()});
}
cbxSipNo.ValueMember = "Value";
cbxSipNo.DisplayMember = "Text";
My problem is while accessing that specified Text and Value fields as below.
if (cbxSipNo.Items.Contains( new { Text= row.Cells[5].Value.ToString()} )
{
//some code
}
While doing contains, I couldn't figure out to access Text field. When i try without new syntax, it looks for Text and Value field combination. How can i do contains in the Text field of ComboBox?
One approach is to create a class.
class MyItem
{
public string Text { get; set; }
public string Value { get; set; }
}
And add your data row value to an object of an above class to combo box like
foreach (DataRow dr in dtSip.Rows)
{
cbxSipNo.Items.Add(new MyItem { Text = Convert.ToString(dr[0]), Value = Convert.ToString(dr[2]) });
}
And then you can cast your combo box items to above MyItem class and then check whether Any item present in combo box that contains your data row value
string str = row.Cells[5].Value;
if (cbxSipNo.Items.Cast<MyItem>().Any(x => Convert.ToString(str).Contains(x.Text)))
{
//some code
}
Is it possible to add to checkedListBox item also value and title
checkedListBox1.Items.Insert(0,"title");
How to add also value?
checkedListBox1.Items.Insert(0, new ListBoxItem("text", "value"));
Try setting the DisplayMember and ValueMember properties. Then you can pass an anonymous object like so:
checkedListBox1.DisplayMember = "Text";
checkedListBox1.ValueMember = "Value";
checkedListBox1.Items.Insert(0, new { Text= "text", Value = "value"})
Edit:
To answer your question below, you can create a class for your item like so:
public class MyListBoxItem
{
public string Text { get; set; }
public string Value { get; set; }
}
And then add them like this:
checkedListBox1.Items.Insert(0, new MyListBoxItem { Text = "text", Value = "value" });
And then you can get the value like this:
(checkedListBox1.Items[0] as MyListBoxItem).Value
I'm trying to get the Tag associated to a value of ComboBox like this way:
var league = ((ComboBoxItem)this.League.SelectedValue).Tag.ToString();
Console.WriteLine(league);
The compiler show me a Invalid Cast Exception
I only want to get the associated Tag of the selected value by user, in particular:
(combobox value and Tag)
-Italy (item) - 10 (Tag)
-France (item) - 12 (Tag)
If the user select Italy, in the code I must get "10". But I can't do this, what am I doing wrong?
UPDATE (Populate combo):
List<RootObject> obj = JsonConvert.DeserializeObject<List<RootObject>>(responseText);
foreach (var item in obj)
{
foreach (var code in nation_code)
{
if (code.Equals(item.League))
{
League.Items.Add(item.Caption);
//link for each team
League.Tag = item.Links.Teams.href;
}
}
}
If you see the Tag is setting for the combo box itself and not for its individual item.
You can build a dictionary and use it as datasource of your combo box. Specify the value and display members of the combo box with dictionary key and value attributes
Try modifying the combo population logic as follows -
List<RootObject> obj = JsonConvert.DeserializeObject<List<RootObject>>(responseText);
Dictionary<string, string> comboSource = new Dictionary<string, string>();
foreach (var item in obj)
{
foreach (var code in nation_code)
{
if (code.Equals(item.League))
{
comboSource.Add(item.Caption, item.Links.Teams.href);
}
}
}
League.ValueMember = "Value";
League.DisplayMember = "Key";
League.DataSource = comboSource;
And then the required values can be fetched using the selectedText and selectedvalue properties.
League.SelectedText; //Return the "item.Caption"
League.SelectedValue; //Return the "item.Links.Teams.href"
For WPF we need to use different properties viz. ItemsSource,
DisplayMemberPath and SelectedValuePath while binding the combo
box. The above solution is for win forms.
You can add any type of object to a ComboBox, it does not need to be a string, it just needs to overwrite .ToString().
You could define a class:
class League {
public string Country { get; set; }
public int Id { get; set; }
public override string ToString() {
return Country;
}
}
and then just add these objects to the ComboBox:
comboBox.Items.Add(new League { Country = "France", Id = 10 });
You can then just cast the SelectedItem of your comboBox back to your class:
var selectedLeague = (League)comboBox.SelectedItem;
//access selectedLeague.Country;
//access selectedLeague.Id;
Could any body give a short example for binding a value from list array to listbox in c#.net
It depends on how your list array is.
Let's start from an easy sample:
List<string> listToBind = new List<string> { "AA", "BB", "CC" };
this.listBox1.DataSource = listToBind;
Here we have a list of strings, that will be shown as items in the listbox.
Otherwise, if your list items are more complex (e.g. custom classes) you can do in this way:
Having for example, MyClass defined as follows:
public class MyClass
{
public int Id { get; set; }
public string Text { get; set; }
public MyClass(int id, string text)
{
this.Id = id;
this.Text = text;
}
}
here's the binding part:
List<MyClass> listToBind = new List<MyClass> { new MyClass(1, "One"), new MyClass(2, "Two") };
this.listBox1.DisplayMember = "Text";
this.listBox1.ValueMember = "Id"; // optional depending on your needs
this.listBox1.DataSource = listToBind;
And you will get a list box showing only the text of your items.
Setting also ValueMember to a specific Property of your class will make listBox1.SelectedValue containing the selected Id value instead of the whole class instance.
N.B.
Letting DisplayMember unset, you will get the ToString() result of your list entries as display text of your ListBox items.
I have a grid, and I'm setting the DataSource to a List<IListItem>. What I want is to have the list bind to the underlying type, and disply those properties, rather than the properties defined in IListItem. So:
public interface IListItem
{
string Id;
string Name;
}
public class User : IListItem
{
string Id { get; set; };
string Name { get; set; };
string UserSpecificField { get; set; };
}
public class Location : IListItem
{
string Id { get; set; };
string Name { get; set; };
string LocationSpecificField { get; set; };
}
How do I bind to a grid so that if my List<IListItem> contains users I will see the user-specific field? Edit: Note that any given list I want to bind to the Datagrid will be comprised of a single underlying type.
Data-binding to lists follows the following strategy:
does the data-source implement IListSource? if so, goto 2 with the result of GetList()
does the data-source implement IList? if not, throw an error; list expected
does the data-source implement ITypedList? if so use this for metadata (exit)
does the data-source have a non-object indexer, public Foo this[int index] (for some Foo)? if so, use typeof(Foo) for metadata
is there anything in the list? if so, use the first item (list[0]) for metadata
no metadata available
List<IListItem> falls into "4" above, since it has a typed indexer of type IListItem - and so it will get the metadata via TypeDescriptor.GetProperties(typeof(IListItem)).
So now, you have three options:
write a TypeDescriptionProvider that returns the properties for IListItem - I'm not sure this is feasible since you can't possibly know what the concrete type is given just IListItem
use the correctly typed list (List<User> etc) - simply as a simple way of getting an IList with a non-object indexer
write an ITypedList wrapper (lots of work)
use something like ArrayList (i.e. no public non-object indexer) - very hacky!
My preference is for using the correct type of List<>... here's an AutoCast method that does this for you without having to know the types (with sample usage);
Note that this only works for homogeneous data (i.e. all the objects are the same), and it requires at least one object in the list to infer the type...
// infers the correct list type from the contents
static IList AutoCast(this IList list) {
if (list == null) throw new ArgumentNullException("list");
if (list.Count == 0) throw new InvalidOperationException(
"Cannot AutoCast an empty list");
Type type = list[0].GetType();
IList result = (IList) Activator.CreateInstance(typeof(List<>)
.MakeGenericType(type), list.Count);
foreach (object obj in list) result.Add(obj);
return result;
}
// usage
[STAThread]
static void Main() {
Application.EnableVisualStyles();
List<IListItem> data = new List<IListItem> {
new User { Id = "1", Name = "abc", UserSpecificField = "def"},
new User { Id = "2", Name = "ghi", UserSpecificField = "jkl"},
};
ShowData(data, "Before change - no UserSpecifiedField");
ShowData(data.AutoCast(), "After change - has UserSpecifiedField");
}
static void ShowData(object dataSource, string caption) {
Application.Run(new Form {
Text = caption,
Controls = {
new DataGridView {
Dock = DockStyle.Fill,
DataSource = dataSource,
AllowUserToAddRows = false,
AllowUserToDeleteRows = false
}
}
});
}
As long as you know for sure that the members of the List<IListItem> are all going to be of the same derived type, then here's how to do it, with the "Works on my machine" seal of approval.
First, download BindingListView, which will let you bind generic lists to your DataGridViews.
For this example, I just made a simple form with a DataGridView and randomly either called code to load a list of Users or Locations in Form1_Load().
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;
using Equin.ApplicationFramework;
namespace DGVTest
{
public interface IListItem
{
string Id { get; }
string Name { get; }
}
public class User : IListItem
{
public string UserSpecificField { get; set; }
public string Id { get; set; }
public string Name { get; set; }
}
public class Location : IListItem
{
public string LocationSpecificField { get; set; }
public string Id { get; set; }
public string Name { get; set; }
}
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void InitColumns(bool useUsers)
{
if (dataGridView1.ColumnCount > 0)
{
return;
}
DataGridViewCellStyle gridViewCellStyle = new DataGridViewCellStyle();
DataGridViewTextBoxColumn IDColumn = new DataGridViewTextBoxColumn();
DataGridViewTextBoxColumn NameColumn = new DataGridViewTextBoxColumn();
DataGridViewTextBoxColumn DerivedSpecificColumn = new DataGridViewTextBoxColumn();
IDColumn.DataPropertyName = "ID";
IDColumn.HeaderText = "ID";
IDColumn.Name = "IDColumn";
NameColumn.DataPropertyName = "Name";
NameColumn.HeaderText = "Name";
NameColumn.Name = "NameColumn";
DerivedSpecificColumn.DataPropertyName = useUsers ? "UserSpecificField" : "LocationSpecificField";
DerivedSpecificColumn.HeaderText = "Derived Specific";
DerivedSpecificColumn.Name = "DerivedSpecificColumn";
dataGridView1.Columns.AddRange(
new DataGridViewColumn[]
{
IDColumn,
NameColumn,
DerivedSpecificColumn
});
gridViewCellStyle.SelectionBackColor = Color.LightGray;
gridViewCellStyle.SelectionForeColor = Color.Black;
dataGridView1.RowsDefaultCellStyle = gridViewCellStyle;
}
public static void BindGenericList<T>(DataGridView gridView, List<T> list)
{
gridView.DataSource = new BindingListView<T>(list);
}
private void Form1_Load(object sender, EventArgs e)
{
dataGridView1.AutoGenerateColumns = false;
Random rand = new Random();
bool useUsers = rand.Next(0, 2) == 0;
InitColumns(useUsers);
if(useUsers)
{
TestUsers();
}
else
{
TestLocations();
}
}
private void TestUsers()
{
List<IListItem> items =
new List<IListItem>
{
new User {Id = "1", Name = "User1", UserSpecificField = "Test User 1"},
new User {Id = "2", Name = "User2", UserSpecificField = "Test User 2"},
new User {Id = "3", Name = "User3", UserSpecificField = "Test User 3"},
new User {Id = "4", Name = "User4", UserSpecificField = "Test User 4"}
};
BindGenericList(dataGridView1, items.ConvertAll(item => (User)item));
}
private void TestLocations()
{
List<IListItem> items =
new List<IListItem>
{
new Location {Id = "1", Name = "Location1", LocationSpecificField = "Test Location 1"},
new Location {Id = "2", Name = "Location2", LocationSpecificField = "Test Location 2"},
new Location {Id = "3", Name = "Location3", LocationSpecificField = "Test Location 3"},
new Location {Id = "4", Name = "Location4", LocationSpecificField = "Test Location 4"}
};
BindGenericList(dataGridView1, items.ConvertAll(item => (Location)item));
}
}
}
The important lines of code are these:
DerivedSpecificColumn.DataPropertyName = useUsers ? "UserSpecificField" : "LocationSpecificField"; // obviously need to bind to the derived field
public static void BindGenericList<T>(DataGridView gridView, List<T> list)
{
gridView.DataSource = new BindingListView<T>(list);
}
dataGridView1.AutoGenerateColumns = false; // Be specific about which columns to show
and the most important are these:
BindGenericList(dataGridView1, items.ConvertAll(item => (User)item));
BindGenericList(dataGridView1, items.ConvertAll(item => (Location)item));
If all items in the list are known to be of the certain derived type, just call ConvertAll to cast them to that type.
You'll need to use a Grid template column for this. Inside the template field you'll need to check what the type of the object is and then get the correct property - I recommend creating a method in your code-behind which takes care of this. Thus:
<asp:TemplateField HeaderText="PolymorphicField">
<ItemTemplate>
<%#GetUserSpecificProperty(Container.DataItem)%>
</ItemTemplate>
</asp:TemplateField>
In your code-behind:
protected string GetUserSpecificProperty(IListItem obj) {
if (obj is User) {
return ((User) obj).UserSpecificField
} else if (obj is Location) {
return ((Location obj).LocationSpecificField;
} else {
return "";
}
}
I tried projections, and I tried using Convert.ChangeType to get a list of the underlying type, but the DataGrid wouldn't display the fields. I finally settled on creating static methods in each type to return the headers, instance methods to return the display fields (as a list of string) and put them together into a DataTable, and then bind to that. Reasonably clean, and it maintains the separation I wanted between the data types and the display.
Here's the code I use to create the table:
DataTable GetConflictTable()
{
Type type = _conflictEnumerator.Current[0].GetType();
List<string> headers = null;
foreach (var mi in type.GetMethods(BindingFlags.Static | BindingFlags.Public))
{
if (mi.Name == "GetHeaders")
{
headers = mi.Invoke(null, null) as List<string>;
break;
}
}
var table = new DataTable();
if (headers != null)
{
foreach (var h in headers)
{
table.Columns.Add(h);
}
foreach (var c in _conflictEnumerator.Current)
{
table.Rows.Add(c.GetFieldsForDisplay());
}
}
return table;
}
When you use autogeneratecolumns it doesnt automatically do this for you?
My suggestion would be to dynamically create the columns in the grid for the extra properties and create either a function in IListItem that gives a list of available columns - or use object inspection to identify the columns available for the type.
The GUI would then be much more generic, and you would not have as much UI control over the extra columns - but they would be dynamic.
Non-checked/compiled 'psuedo code';
public interface IListItem
{
IList<string> ExtraProperties;
... your old code.
}
public class User : IListItem
{
.. your old code
public IList<string> ExtraProperties { return new List { "UserSpecificField" } }
}
and in form loading
foreach(string columnName in firstListItem.ExtraProperties)
{
dataGridView.Columns.Add(new DataGridViewTextBoxColumn { DataPropertyName = columnName, HeaderText = columnName );
}
If you are willing to use a ListView based solution, the data-bindable version ObjectListView will let you do this. It reads the exposed properties of the DataSource and creates columns to show each property. You can combine it with BindingListView.
It also looks nicer than a grid :)