I'm reading in a field from a database into a list, like so
PaceCalculator pace = new PaceCalculator();
List<PaceCalculator> Distancelist = new List<PaceCalculator>();
while (Reader.Read()) //Loops through the database and adds the values in EventDistance to the list
{
pace.Distance = (int)Reader["EventDistance"];
Distancelist.Add(pace);
}
I want to put the values into a listbox, but when I do it like this:
listBox1.DataSource = Distancelist;
It only shows the class name, which is PaceCalculator. It shows the right number of values, it just shows the class name instead. I want to see the integers in there.
You have two options,
Override ToString in your class to return the required string
or, if you only want to display Distance then specify that as DisplayMember
like:
listBox1.DisplayMember = "Distance";
listBox1.DataSource = Distancelist;
This will display you the Distance element from your list. Or you can override ToString in your class PaceCalculator like:
public override string ToString()
{
return string.Format("{0},{1},{2}", property1, property2, property3);
}
EDIT:
Based on your comment and looking at your code, You are doing one thing wrong.
this only displays the last value in the list, 46, 8 times
You are adding the same instance (pace) of your class in your list on each iteration. Thus it is holding the last value (46). You need to instantiate a new object in the iteration like:
while (Reader.Read())
{
PaceCalculator pace = new PaceCalculator();
pace.Distance = (int)Reader["EventDistance"];
Distancelist.Add(pace);
}
Specify the property of PaceCalculator to display.
listBox1.DataSource = Distancelist;
listBox1.DisplayMember = "Distance";
The ListBox control allows you to pick a property from the collection to display to the user.
There's also a ValueMember property that allows you to specify the value for each item in the ListBox. Assuming your data included an id called "SomeUniqueRecordId", for instance:
listBox1.ValueMember = "SomeUniqueRecordId";
Related
In my WPF app, i have a Window(all code) that contains DataGrid. There's my DataGrid binding:
using (var db = new CompanyEntities())
{
var stocks = db.Stock;
var query = from s in stocks
select new { s.Id_Product, s.Quantity };
dataGrid.ItemsSource = query.ToList();
}
I want to read cell that is selected in DataGrid. I tried to read it using DataGrid.SelectedItem, but to get to the item i have to cast it to some type. I can't use Stock class, because my DataGrid cells contains 2 out of 3 fields of Stock. So i made another class to represent DataGrid cell:
class TableItem
{
public int Id_Product;
public int? Quantity;
}
And tried to cast it like this:
TableItem x = (TableItem)dataGrid.SelectedItem;
But i get InvalidCastException from type:
'<>f__AnonymousType02[System.Int32,System.Nullable1[System.Int32]]'
to my TableItem type.
So how should i get selected cell of my dataGrid?
My walkaround:
In my CompanyEntites constructor i set:
this.Configuration.ProxyCreationEnabled = false;
And now i can cast Stock s = (Stock)dataGrid.SelectedItem;without an exception, before switching ProxyCreation off, my SelectedItem was DynamicProxy.Stock~~ type.
Change your query like so:
var query = from s in stocks
select new TableItem { Id_Product = s.Id_Product, Quantity = s.Quantity };
And then cast SelectedItem to TableItem, now that it actually IS one. In C#, just because it looks like another class, doesn't mean it is that other class.
Alternatively, don't write a new class just because you happen not to need one property of the existing class. Just use the existing class:
// Don't think you need to call ToList() here
dataGrid.ItemsSource = db.Stock;
...and cast SelectedItem to whatever that is.
my DataGrid cells contains 2 out of 3 fields of Stock:
So what? Is the problem that you get an extra column? Define the columns explicitly, just the ones you need.
I have a custom object with several properties, one of which returns a list. This is the code for the object:
public class SearchResult
{
private int eventId;
private String eventTitle;
private int startDate;
private List<String> tags;
// Properties
public int EventId { get { return this.eventId; } }
public String EventTitle { get { return this.eventTitle; } }
public int StartDate { get { return this.startDate; } }
public List<String> Tags { get { return this.tags; } }
public SearchResult(int eventId, String eventTitle, int startDate, List<String> tags)
{
// Constructor code
}
public List<String> GetTags()
{
return this.tags;
}
}
I also have a DataGridViewComboBoxColumn that I want to bind to the Tags property. Basically, each SearchResult object will be displayed in its own row, and I want the List<String> in the Tags property of each object to be displayed in a ComboBox cell in that row. This is the code I have so far for my DataGridView:
BindingList<SearchResult> results = new BindingList<SearchResult>();
results.Add(new SearchResult(1, "This is a title", 2012, new List<String> { "Tag1", "Tag with a long name1" }));
results.Add(new SearchResult(2, "The quick brown fox", 2012, new List<String> { "Stack", "Overflow" }));
results.Add(new SearchResult(3, "In this tutorial, you create a class that is the type for each object in the object collection. ", 2012, new List<String> { "NYSE", "FTSE" }));
results.Add(new SearchResult(4, "another long piece of title text", -999, new List<String> { "Rabbits", "Chickens" }));
MyDataGrid.AutoGenerateColumns = false;
MyDataGrid.AllowUserToAddRows = false;
MyDataGrid.AllowUserToDeleteRows = false;
MyDataGrid.AutoSizeColumnsMode = System.Windows.Forms.DataGridViewAutoSizeColumnsMode.None;
MyDataGrid.BackgroundColor = System.Drawing.SystemColors.Control;
MyDataGrid.ColumnHeadersHeightSizeMode = System.Windows.Forms.DataGridViewColumnHeadersHeightSizeMode.AutoSize;
MyDataGrid.RowHeadersWidthSizeMode = System.Windows.Forms.DataGridViewRowHeadersWidthSizeMode.AutoSizeToDisplayedHeaders;
MyDataGrid.AutoSizeRowsMode = System.Windows.Forms.DataGridViewAutoSizeRowsMode.DisplayedCells;
MyDataGrid.DefaultCellStyle.WrapMode = DataGridViewTriState.True;
DataGridViewTextBoxColumn eventIdColumn = new DataGridViewTextBoxColumn();
eventIdColumn.DataPropertyName = "EventId";
eventIdColumn.HeaderText = "Event ID";
eventIdColumn.ReadOnly = true;
eventIdColumn.Width = 84;
DataGridViewTextBoxColumn eventTitleColumn = new DataGridViewTextBoxColumn();
eventTitleColumn.DataPropertyName = "EventTitle";
eventTitleColumn.HeaderText = "Event Title";
eventTitleColumn.ReadOnly = true;
eventTitleColumn.Width = 368;
DataGridViewTextBoxColumn startDateColumn = new DataGridViewTextBoxColumn();
startDateColumn.DataPropertyName = "StartDate";
startDateColumn.HeaderText = "Start Date";
startDateColumn.ReadOnly = true;
startDateColumn.Width = 130;
//I think I need to insert the code for the tags column here, but I'm not sure
MyDataGrid.Columns.Add(eventIdColumn);
MyDataGrid.Columns.Add(eventTitleColumn);
MyDataGrid.Columns.Add(startDateColumn);
//MyDataGrid.Columns.Add(tagsColumn);
MyDataGrid.DataSource = results;
I derived this code from a tutorial I found online, and it works perfectly.
I've been trying to bind the Tags property of SearchResult to a DataGridViewComboBoxColumn, but I'm not sure how. I've been looking at this question, which provides this code:
column.DataPropertyName = "Foo";
column.DisplayMember = "SomeNameField";
column.ValueMember = "Bar"; // must do this, empty string causes it to be
// of type string, basically the display value
// probably a bug in .NET
column.DataSource = from foo in Foo select foo;
grid.DataSource = data;
The reason I'm having trouble is because of a few nuances of the linked question that I don't understand.
According to the documentation and the linked question, DisplayMember should be linked to the property that "contains a description of the instance", but since SearchResult objects are added dynamically and don't have any description associated with them, should I just leave it blank?
ValueMember is giving me similar problems, since I'm unsure what to put even after reading its documentation.
In the linked question, the accepted answer binds the entire datagrid at once using LINQ. Is that how I should be doing this? I'm not sure how to modify that code for my situation, but I thought it would be something along these lines.
:
tagsColumn.DataPropertyName = "Tags";
tagsColumn.DisplayMember = ""; // I'm unsure of what to put here
tagsColumn.ValueMember = ""; // Once again, I don't know what to set this to
I also presume I should have a line that sets the DataSource for the column, e.g.
tagsColumn.DataSource = <some LINQ query, perhaps?>
but I don't know because the only mostly relevant C# source I've been able to find is that question.
UPDATE:
I did find a second question that suggests code similar to this for data binding:
// reference the combobox column
DataGridViewComboBoxColumn cboBoxColumn = (DataGridViewComboBoxColumn)dataGridView1.Columns[0];
cboBoxColumn.DataSource = Choice.GetChoices();
cboBoxColumn.DisplayMember = "Name"; // the Name property in Choice class
cboBoxColumn.ValueMember = "Value"; // ditto for the Value property
Based on that, I a) added the GetTags() method to SearchResult and added this code into my DataGridView initialisation code:
DataGridViewComboBoxColumn tagsColumn = new DataGridViewComboBoxColumn();
tagsColumn.DataSource = SearchResult.GetTags(); // ERROR
tagsColumn.DisplayMember = ""; // Still not sure
tagsColumn.ValueMember = ""; // ??
However, Visual Studio gives me an error on the second line when I try to run this:
An object reference is required for the non-static field, method, or property 'SearchResult.GetTags()'
UPDATE 2:
I'm still searching around for this without success. I don't understand how with other properties (e.g. EventId) I can simply declare the data property name as EventId, and it will display in the table, but I cannot do this with ComboBox columns.
Since the objects are instantiated in a separate class and put in a list, it doesn't seem to make sense to me that I should have to loop through the entire array of objects (of which there may be several hundred) to bind the Tags property to the ComboBox column for each instance, when I don't need to loop through the list of SearchResult objects to bind other properties, e.g. EventId.
Why does this binding-properties-by-name only work for some properties and not others?
I don't quite understand why you want to use DataGridViewComboBoxColumn to display a list of elements. This column kind is designed to allow user to select one of many possibilities. It seams it is not your case because you don't have public string SelectedTag{get;set;} property to store it. As I understand your model you have many tags already selected for your SearchResult and you want to display them in grid.
As documentation states:
http://msdn.microsoft.com/en-us/library/system.windows.forms.datagridviewcomboboxcolumn.datasource
Getting or setting this [DataSource] property gets or sets the DataSource property of the object returned by the CellTemplate property. Setting this property also sets the DataSource property of every cell in the column and refreshes the column display. To override the specified value for individual cells, set the cell values after you set the column value.
DataGridViewComboBoxColumn simply does not have capability to bind items property to data source because it assumes that there is only one list of elements that is used as data source for all rows of data grid.
I also assume that you would set ReadOnly = true property for this column as you have for all other. If so it would prevent user form seeing list of tags because drop down list would never be displayed.
If you wand to display list of strings in read only mode I would suggest to flatten this list of tags to single string:
public string Tags { get { return string.Join(", ", tags); } }
and display it in text column.
For the error , i can suggest you to make an instance of the class and then call the method as its not static or you can make your method static.
Moreover As you needs the comboboxcolumn ,
DataGridViewComboBoxColumn tagsColumn = new DataGridViewComboBoxColumn();
tagsColumn.DataSource = SearchResult.GetTags(); // ERROR
tagsColumn.DisplayMember = ""; // Still not sure
tagsColumn.ValueMember = ""; // ??
Mostly we have dropdowns for objects like Country(id,name) so DisplayMember = name will be shown as text in dropdown while ValueMember = id will be used in the referencing tables in database.But this is not your case.
Here you have a list of strings to show in dropdown , so you don't need to set them.
As written here
If the DataSource property is set to a string array, then ValueMember
and DisplayMember do not need to be set because each string in the
array will be used for both value and display.
I'm not sure why this isn't working. I'm trying to display 2 columns from my database side by side in a listview box on my form. When I use this it doesn't display any of the data correctly.
("SELECT Person FROM tblPeople" + " SELECT Occur FROM tblpeople" , conn);
try
{
SqlDataReader reader = cmd.ExecuteReader();
while (reader.Read())
{
listView1.Items.Add(reader["People"].ToString());
listView1.Items.Add(reader["Occur"].ToString());
}
So i'm looking for my data to display like this:
John 3
James 4
Frank 1
As the names are coming from column People and the numbers are coming from column Occur.
To get the desired effect, you should set the view style to Details and add the second column value as sub-item.
Basically, you should do something like this:
listView1.View = View.Details;
listView1.Columns.Add("People");
listView1.Columns.Add("Occur");
while (reader.Read())
{
var item = new ListViewItem();
item.Text = reader["People"].ToString(); // 1st column text
item.SubItems.Add(reader["Occur"].ToString()); // 2nd column text
listView1.Items.Add(item);
}
Method Add() adds every time a new item to the collection. If your item consists of values from two objects, probably the easiest way would be to create a new item to encapsulate it, so you can easily bind it to your controls.
Consider something like this:
public class MyNewObject
{
public string People { get;set; }
public string Occur { get;set; }
public MyNewObject(string p, string o)
{
People = p;
Occur = o;
}
}
and then just
while (reader.Read())
{
listView1.Items.Add(new MyNewObject(reader["People"].ToString(),reader["Occur"].ToString()));
}
I'm using SubSonic 2.2 for my DAL and extended one of my classes with a calculated property that returns a string containing another property with indenting based on the level of the outline at which the item occurs. The code for the property is below. The problem is that when I try to use this property as the DisplayMember for a ListBox control on a form (the reason I wrote it in the first place) it won't work. The ListBox reverts to displaying the ID property which is set as the ValueMember. To test that the property was working I looped through the collection of objects that I was populating the ListBox with and, using MessageBox.Show(obj.property), confirmed that it was indeed returning the value I'm looking for. Am I missing something or should this work? btw - There may be a better way to do the indenting but that's not what I'm after at the moment, thanks!
Code follows:
public partial class InteriorsCategory : ActiveRecord, IActiveRecord
{
public string ListDisplay
{
get
{
string returnValue = "";
for (int i = 1; i < this.SpecLevel; i++)
{
returnValue += " ";
}
returnValue += this.CategoryName;
return returnValue;
}
}
}
<>
I definitely get data in my collection and the binding I'm doing is exactly the same as yours (binding code posted below). The return value of the ListDisplay property that I'm using is a string concatenation of two values in the object. Think of it as a "full name" property that concatenates the FirstName a space and the LastName properties into a single string which it returns. I am trying to bind the ListDisplay property to the DisplayMember property of the listbox, but all that shows in the listbox is the Id field which I am binding to the ValueMember.
private void FillCategories()
{
lstPackageCategories.DataSource = new InteriorsCategoryCollection().Load();
lstPackageCategories.DisplayMember = "CategoryName";
lstPackageCategories.ValueMember = "Id";
((InteriorsCategoryCollection)(lstPackageCategories.DataSource)).Sort("SpecSection", true);
lstPackageCategories.SelectedItem = lstPackageCategories.Items[0];
currentCategory = (InteriorsCategory)lstPackageCategories.SelectedItem;
RefreshAvailableItems();
}
If your able to see your data in the collection, then it sounds like there is a problem on the binding of your ListBox. Here is an example of how I bind a ListBox using a SubSonic collection of values.
ISOCountryCodeCollection countrys =
new ISOCountryCodeCollection().OrderByAsc(ISOCountryCode.Columns.Country).Load();
Country.DataSource = countrys;
Country.DataValueField = "ThreeChar";
Country.DataTextField = "Country";
Country.DataBind();
In the example above, I'm binding the 3 character country code to the "DataValueField" and the full country name to the "DataTextField".
My project display's program names from the database into dropdownlist and each program has a ID. I want to display both name and id in the dropdownlist so that they can be differenciated from each other.
eg: 'california lifeline (CLA)'
where 'california lifeline' is the name of the program and the id is 'CLA'. I have created a stored procedure which displays data based on the program ID.
This the code of my dropdownlist control.
private void LoadProgramName()
{
_drp_program = (DropDownList)Page.FindControl("bodyuc$drp_program");
dsprg = rProxy.GlobalFetchFromDB(strCountyName, "DBO.oea_sp_get_onoff_programNames");
_drp_program.DataSource = dsprg;
_drp_program.DataTextField = "PROG_NAME";
_drp_program.DataValueField = "PROGRAM_ID";
_drp_program.DataBind(); ;
ListItem lst_prog = new ListItem();
lst_prog.Value = "";
lst_prog.Text = "--Select One--";
_drp_program.Items.Insert(0, lst_prog);
_drp_program.Items.Insert(1, "ALL");
}
BTW, the dropdown is a part of pagecontrol.
Help is Appriceated.
If your GlobalFetchFromDB() returns instances of an object which you can "extend" as a partial class, then I'd add a "helper" property to the class that formats your displayed string.
One advantage to this is that the format can be dependent on the values of other properties in the instance.
For example:
public partial class ProgramItem
{
public string DisplayName { get { return PROG_NAME.ToUpper(); } }
}
Then use _drp_program.DataTextField = "DisplayName";
An alternative is to construct a class that encapsulates the returned items and adds the DisplayName as a decorator.
Instead of binding _drp_program to dsprg, loop through the results in dsprg and add each item individually.
foreach(dsprgObject in dsprg)
{
_drp_program.Items.add(new ListItem(dsprgObject .ColA + " " + dsprgObject .ColB, dsprgObject.PROGRAM_ID));
}
You can try
_drp_program.DataSource = from item in dsprg
select new
{
PROG_NAME = string.Format("{0}({1})", item.PROG_NAME, item.PROGRAM_ID) ,
PROGRAM_ID = item.PROGRAM_ID
};
instead of
_drp_program.DataSource = dsprg;
Usually the fastest way is to concatenate ID and NAME in an SQL query (but you're using an sp so that's a bit difficult). Also, since you binding your control in code, you can concatenate ID and Name in code and populate your dropdownlist manually (either by calling Items.Insert or by binding your dropdown to a collection which members have a field/property that contains the concatenated value). AFAIK, you can only specify a field/property name for DataTextField and DataValueField, no expressions etc...