Question

我正在构建一系列winforms应用程序，并且我需要在选择国家/地区城市列表时填写具有2个组合“国家和城市”的propertyGrid。

我一直在寻找一个例子，却找不到任何例子。

任何地方的任何链接或codenippet？

非常感谢

Answer 1

你需要TypeConverters，一个用于城市，一个用于国家：

public class CountryCity {

  [TypeConverter(typeof(CountryConverter))]
  public string Country { get; set; }

  [TypeConverter(typeof(CityConverter))]
  public string City { get; set; }

  private static List<CountryCity> cityList = new List<CountryCity>();

  static CountryCity() {
    cityList.Add(new CountryCity() { Country = "Germany", City = "Berlin" });
    cityList.Add(new CountryCity() { Country = "Germany", City = "Hamburg" });
    cityList.Add(new CountryCity() { Country = "Germany", City = "Munich" });
    cityList.Add(new CountryCity() { Country = "US", City = "Atlanta" });
    cityList.Add(new CountryCity() { Country = "US", City = "Chicago" });
    cityList.Add(new CountryCity() { Country = "US", City = "Los Angeles" });
    cityList.Add(new CountryCity() { Country = "US", City = "New York" });
  }

  public class CityConverter : TypeConverter {
    public override bool GetStandardValuesSupported(ITypeDescriptorContext context) {
      return true;
    }

    public override StandardValuesCollection GetStandardValues(ITypeDescriptorContext context) {
      List<string> cities = new List<string>();

      CountryCity cc = context.Instance as CountryCity;
      if (cc != null) {
        if (cc.Country == null) {
          cities.AddRange(cityList.Select(x => x.City));
        } else {
          cities.AddRange(cityList.Where(x => x.Country == cc.Country)
                                  .Select(y => y.City));
        }
      }
      return new StandardValuesCollection(cities);
    }

    public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType) {
      if (sourceType == typeof(string)) {
        return true;
      }
      return base.CanConvertFrom(context, sourceType);
    }

    public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value) {
      if (value is string) {
        foreach (CountryCity cc in cityList) {
          if (cc.City == (string)value) {
            return cc.City;
          }
        }
      }
      return base.ConvertFrom(context, culture, value);
    }
  }

  public class CountryConverter : TypeConverter {
    public override bool GetStandardValuesSupported(ITypeDescriptorContext context) {
      return true;
    }

    public override StandardValuesCollection GetStandardValues(ITypeDescriptorContext context) {
      List<string> items = cityList.Select(x => x.Country).Distinct().ToList();
      return new StandardValuesCollection(items);
    }

    public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType) {
      if (sourceType == typeof(string)) {
        return true;
      }
      return base.CanConvertFrom(context, sourceType);
    }

    public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value) {
      if (value is string) {
        foreach (CountryCity cc in cityList) {
          if (cc.Country == (string)value) {
            return cc.Country;
          }
        }
      }
      return base.ConvertFrom(context, culture, value);
    }
  }
}

进行测试：

propertyGrid1.SelectedObject = new CountryCity();

Answer 2

创建一个具有1个静态函数的类国家/地区，以检索所有已知国家/地区

class Countries
{
 public string Country{get;set;}
 public int CountryId {get;set;}

 public static List<Countries>MyCountries()
 {
  var c1 = new Countries{ Country = "Belgium", CountryId = 1};
  var c2 = new Countries{ Country = "Netherlands", CountryId = 2};

  var result= new List<Countries>();
  result.Add(c1);
  result.Add(c2);

  return result;
 }
}

使用静态函数创建一个类城市来检索所有城市，使用另一个静态函数来搜索第一个函数。

class Cities
{
 public string City{get;set;}
 public int CityId{get;set;}
 public int CountryId{get;set;}

 public static List<Cities>MyCities()
 {
  var c1 = new Cities{ CityId = 1, City= "Antwerp", CountryId = 1};
  var c2 = new Cities{ CityId = 2, City= "Den Haag", CountryId = 2};
  var c3 = new Cities{ CityId = 3, City= "Brussels", CountryId = 1};
  var c4 = new Cities{ CityId = 4, City= "Rotterdam", CountryId = 2};
  var c5 = new Cities{ CityId = 5, City= "Amsterdam", CountryId = 2};
  var c6 = new Cities{ CityId = 6, City= "Hasselt", CountryId = 1};

  var result= new List<Cities>();
  result.Add(c1);
  result.Add(c2);
  result.Add(c3);
  result.Add(c4);
  result.Add(c5);
  result.Add(c6);

  return result;
 }

 public static List<Cities>SelectedCities(int countryId)
 {
  //Linq Example
  var l = MyCities();
  var result = from m in l 
               where m.CountryId = countryId
               select m;
  return result;

  //you also could use a foreach or For loop
  //var l = MyCities();
  //var result = new List<Cities>();
  //foreach(var item in l)
  //{
  // if(item.CountryId == countryId)
  // { 
  //  result.Add(item);
  // }
  // return result;
  }
 }
}

在您的表单或usercontrol中添加以下代码：

public Form1()
{
 InitializeComponent(); //initialises the component
 PopulateCountryBox();  //populate the combobox
 combobox1.SelectedIndexChanged += combobox1_SelectedIndexChanged; //Create the event          
}

在form_load或其他地方调用下面的函数来加载CountryBox

private void PopulateCountryBox()
{
 var countryList = new List<Countries>();
 combobox1.DataSource = countryList;
 combobox1.DisplayMember = "Country";
 combobox1.ValueMember = "CountryId"; 
}

代码下面的

将处理combobox1 selectedindexChanged事件

private void combobox1_SelectedIndexChanged(object sender, EventArgs e)
{
 var cityList = new List<Cities>(combobox1.SelectedValue);
 combobox2.DataSource = cityList;
 combobox2.DisplayMember = "City";
 combobox2.ValueMember = "CityId"; 
}

我希望这能为你提供一个足够好的榜样，随时提出更多问题

在属性网格c＃4.0中级联组合框

2 个答案: