[英]How to Set default combobox
So I've been looking to set a default value for my combobox. 所以我一直在寻找为我的组合框设置一个默认值。 I found a few things but none of them seem to work. 我发现了一些东西但它们似乎都没有用。
Actually, it works if I create a simple combobox and use comboBox1.SelectedIndex = comboBox1.Items.IndexOf("something")
but once I dynamically generate the contents of the comboboxes, I can't get it to work anymore. 实际上,它是有效的,如果我创建一个简单的组合框并使用comboBox1.SelectedIndex = comboBox1.Items.IndexOf("something")
但一旦我动态生成组合框的内容,我不能让它工作了。
This is how I fill my combo box (located in the class's constructor); 这是我填充我的组合框(位于类的构造函数中);
string command = "SELECT category_id, name FROM CATEGORY ORDER BY name";
List<string[]> list = database.Select(command, false);
cbxCategory.Items.Clear();
foreach (string[] result in list)
{
cbxCategory.Items.Add(new ComboBoxItem(result[1], result[0]));
}
I can't seem to get it to work to set a default value, like if I place cbxCategory.SelectedIndex = cbxCategory.Items.IndexOf("New")
below the above code, it won't work. 我似乎无法让它设置一个默认值,就像我在上面的代码下面放置cbxCategory.SelectedIndex = cbxCategory.Items.IndexOf("New")
,它将无法正常工作。
WinForms, by the way. 顺便说一句,WinForms。
Thank you in advance. 先感谢您。
cbxCategory.SelectedIndex
should be set to an integer from 0
to Items.Count-1
like cbxCategory.SelectedIndex
应设置为0
到Items.Count-1
的整数
cbxCategory.SelectedIndex = 2;
your 您的
cbxCategory.SelectedIndex = cbxCategory.Items.IndexOf("New")
should return -1 as long as no ComboboxItem mutches the string ("New"); 只要没有ComboboxItem变换字符串(“New”),就应该返回-1;
another solution though i don't like it much would be 另一个解决方案,虽然我不喜欢它会有多少
foreach(object obj in cbxCategory.Items){
String[2] objArray = (String[])obj ;
if(objArray[1] == "New"){
cbxCategory.SelectedItem = obj;
break;
}
}
perhaps this also requires the following transformation to your code 也许这也需要对您的代码进行以下转换
foreach (string[] result in list)
{
cbxCategory.Items.Add(result);
}
I haven't tested the code and i am not sure about the casting to String[2] but something similar should work 我没有测试代码,我不确定转换为String [2],但类似的东西应该工作
It looks like you're searching the cbxCategory.Items collection for a string, but it contains items of type ComboBoxItem. 看起来您正在搜索cbxCategory.Items集合中的字符串,但它包含ComboBoxItem类型的项目。 Therefore the search will return -1. 因此搜索将返回-1。
You can use LINQ. 您可以使用LINQ。
//string command = "SELECT category_id, name FROM CATEGORY ORDER BY name";
//List<string[]> list = database.Select(command, false);
// sample data...
List<string[]> list = new List<string[]> { new string[] { "aaa", "bbb" }, new string[] { "ccc", "ddd" } };
cbxCategory.Items.Clear();
foreach (string[] result in list)
{
cbxCategory.Items.Add(new ComboBoxItem(result[1], result[0]));
}
ComboBoxItem tmp = cbxCategory.Items.OfType<ComboBoxItem>().Where(x => x.ResultFirst == "bbb").FirstOrDefault();
if (tmp != null)
cbxCategory.SelectedIndex = cbxCategory.Items.IndexOf(tmp);
ComboBoxItem
class: ComboBoxItem
类:
class ComboBoxItem
{
public string ResultFirst { get; set; }
public string ResultSecond { get; set; }
public ComboBoxItem(string first, string second)
{
ResultFirst = first;
ResultSecond = second;
}
}
Here's my simple solution 这是我的简单解决方案
var list = comboBox1.Items.Cast<string>().ToList();
cbxCategory.SelectedIndex = list.FindIndex(c => c.StartsWith("test"));
My solution: 我的解决方案
int? defaultID = null;
foreach (DataRow dr in dataSource.Tables["DataTableName"].Rows)
{
if ((dr["Name"] != DBNull.Value) && ((string)dr["Name"] == "Default Name"))
{
defaultID = (int)dr["ID"];
}
}
if (defaultID != null) comboBox.SelectedValue = defaultID;
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