数据绑定期间如何在datagridview中自定义格式数据

Question

我正在寻找一种格式化 DataGridViewTextBoxColumn 的方法，以便在数据绑定期间格式化要数据绑定的值。例如，我有一个 CompanyName 属性，当数据绑定发生时，我需要从 CompanyName 中获取前 5 个字母。

我可以挂钩不同的 DataGridView 事件（例如 RowsAdded）并遍历所有行并完成此操作，但我想找到更复杂的方法来做到这一点。由于我决定使用数据绑定，因此循环访问数据并对其进行修改有点违反数据绑定的概念。

我所追求的是如何做与下面相同的事情，但添加自定义格式化逻辑：

dataGridView1.Columns[colSomeDate.Index].DataPropertyName = "SomeDate";
colSomeDate.DefaultCellStyle.Format = "yyyy";

我认为我应该实现 IFormatProvider，但我不太明白我应该如何实现它。

dataGridView1.Columns[companyName.Index].DataPropertyName = "CompanyName";
companyName.DefaultCellStyle.FormatProvider = new ShortText(); // ShortText should implement IFormatProvider

Answer 1

我不知道 IFormatProvider，但是 DataGridViews CellFormatting-event 能帮到你吗？

private void dataGridView1_CellFormatting(object sender,
    DataGridViewCellFormattingEventArgs e)
{
    if (e.ColumnIndex == 0)
    {
        e.Value = e.Value.ToString().Substring(0, 5); // apply formating here
        e.FormattingApplied = true;
    }
}

http://msdn.microsoft.com/en-us/library/z1cc356h.aspx?ppud=4

Answer 2

向您的类添加一个属性，为您执行子字符串，并绑定到它。

Answer 3

这是我的工作让我的工作

public class MyFormatProvider : IFormatProvider, ICustomFormatter  
{  
   public object GetFormat(Type formatType)  
   {  
     if (formatType == typeof(ICustomFormatter))  
        return this;  
     else  
        return null;  
   }  

   public string Format(string format, object arg, IFormatProvider formatProvider)  
   {  
     // Check whether this is an appropriate callback               
     if (!this.Equals(formatProvider))  
        return null;  

     //if argument/ value is null we return empty string  
     if (arg == null)  
        return null;  

     string resultString = arg.ToString();  

     //transform resultString any way you want (could do operations based on given format parameter)  

     //return the resultant string  
     return resultString;  
   }  
}  

这就是我随后放入单元格格式处理程序的内容

//In your datagridview, handle the cell formatting event in required cell as  
if (e.ColumnIndex == dgvPayments.Columns["amount"].Index)  
{  
  e.Value = String.Format(new MyFormatProvider (), "{0:U}", e.Value);  
  e.FormattingApplied = true;  
}  

Answer 4

听起来 IFormatProvider 正是您所需要的。然后，您可以为不同的视图定义不同的代码。

来自Codeproject。

public override string ToString()
{
    return ToString("g", null); // Always support "g" as default format.
}

public string ToString(string format)
{
  return ToString(format, null);
}

public string ToString(IFormatProvider formatProvider)
{
  return ToString(null, formatProvider);
}

public string ToString(string format, IFormatProvider formatProvider)
{
  if (format == null) format = "g"; // Set default format, which is always "g".
  // Continue formatting by checking format specifiers and options.
}

Answer 5

这是我用于实现IFormattable 和ICustomFormatter 的示例的代码sn-p。

Implements IFormattable
Implements ICustomFormatter

Public Function Format(ByVal formatExpression As String, ByVal arg As Object, ByVal formatProvider As System.IFormatProvider) As String Implements System.ICustomFormatter.Format
    'type is currently ignored
    '   if type is international then "USPS" should result in international address
    '   if type is international then "US" should result in international address
    '   and so on
    '

    '.NET Framework Class Library
    'IFormattable Interface
    'Remarks - A class that implements IFormattable must support the "G" (general) formatting code. Besides the "G" code, the class can define the list of formatting codes that it supports.

    'is G and g the same?
    '   yes for numeric
    '   no for date/time

    'Standard Numeric Format Strings
    '   G or g - both are the same
    'Standard DateTime Format Strings
    '   g - General date/time pattern (short time)
    '   G - General date/time pattern (long time)


    If Len(formatExpression) = 0 Then
        Return String.Format("{0}", arg)
    End If

    'usps - standardized
    'us - address less country
    'international - all address lines

    If formatExpression.Equals("g") Then
        'general formatting code
        '   as per documentation
        Return GatherAddress(_line1, _line2, _city, _state, _zip, _country, _type, AddressFormat.StandardUS)

    ElseIf formatExpression.Equals("G") Then
        'general formatting code
        '   as per documentation
        Return GatherAddress(_line1, _line2, _city, _state, _zip, _country, _type, AddressFormat.Standardized)

    ElseIf formatExpression.ToUpper.Equals("USPS") Then
        Return GatherAddress(_line1, _line2, _city, _state, _zip, _country, _type, AddressFormat.Standardized)

    ElseIf formatExpression.ToUpper.Equals("US") Then
        Return GatherAddress(_line1, _line2, _city, _state, _zip, _country, _type, AddressFormat.StandardUS)

    ElseIf formatExpression.ToUpper.Equals("INTERNATIONAL") Then
        Return GatherAddress(_line1, _line2, _city, _state, _zip, _country, _type, AddressFormat.International)

    Else
        Return MyBase.ToString()

    End If

End Function

Public Overloads Function ToString(ByVal format As String, ByVal formatProvider As System.IFormatProvider) As String Implements System.IFormattable.ToString
    Return Me.Format(format, Nothing, formatProvider)
End Function

Answer 6

您总是可以像这样从您的 aspx 页面调用自定义格式函数：

<asp:GridView ID="gvPlatforms" runat="server" AutoGenerateColumns="false"
          GridLines="None">
<Columns>
    <asp:TemplateField HeaderText="Icon">
        <ItemTemplate>
            <asp:Image ID="imgPlatformLogo" runat="server" ImageUrl='<%#GetImagePath(Eval("Abbr")) %>' />
        </ItemTemplate>
    </asp:TemplateField>
</Columns>

然后在该页面后面的代码中：

protected string GetImagePath(object abbr){
return string.Format("{0}{1}.gif", Constants.URLs.PLATFORM_LOGOS, abbr.ToString());}

Answer 7

我通常将 ValueConverters 用于此类行为。

类似：

<DataGridTextColumn Binding={Binding CompanyName, Converter={StaticResource CompanyNameShortenerConverter}} />

在控件/页面的资源节点中，您需要添加如下内容：

<local:CompanyNameConverter x:Key="CompanyNameShortenerConverter" />

CompanyNameShortenerConverter 应该实现 IValueConverter，您可以添加逻辑来“缩短”在“Convert”方法中传入的公司名称。

这使格式化/UI 逻辑与业务逻辑分开（即无需添加缩短名称的“辅助属性”）。