C# BindingSource。查找多个列

可以在多个列上使用BindingSource的Find方法吗

例如，假设我有一个显示当前宠物的gridview；两个组合框，cboPetType和cboGender；以及一个按钮，用于根据这两个组合框的值在Pet表中创建新记录

现在，让我们假设我只想要一个宠物类型/性别组合狗-M，猫-F，等等。。因此，如果我的BindingSource中有一只Dog-M宠物，并且用户从组合框中选择了Dog和M，我会阻止用户通知他们组合已经存在

在过去，我使用BindingSource.Find方法来执行类似的操作，但据我所知，这只适用于搜索一列，即BindingSource.FindPetType、cboPetType.SelectedValue

---

是否可以基于多个列搜索bindingsource？如果没有，有什么建议可以达到我想要的结果吗？非常感谢您的建议

不，不幸的是这是不可能的。虽然给定一个特定的数据源，这样的搜索可能会相当简单，但像BindingSource那样以更通用的方式进行搜索会有点不透明。首先，语法不太明显。下面是一个有点做作的解决方案：

public class Key
{
    public string PropertyName {get; set;}
    public object Value {get; set;}
}

public static int Find(this BindingSource source, params Key[] keys)
{
    PropertyDescriptor[] properties = new PropertyDescriptor[keys.Length];

    ITypedList typedList = source as ITypedList;

    if(source.Count <= 0) return -1;

    PropertyDescriptorCollection props;

    if(typedList != null) // obtain the PropertyDescriptors from the list
    {
        props = typedList.GetItemProperties(null);
    }
    else // use the TypeDescriptor on the first element of the list
    {
        props = TypeDescriptor.GetProperties(source[0]);
    }

    for(int i = 0; i < keys.Length; i++)
    {
        properties[i] = props.Find(keys[i].PropertyName, true, true); // will throw if the property isn't found
    }

    for(int i = 0; i < source.Count; i++)
    { 
        object row = source[i];
        bool match = true;

        for(int p = 0; p < keys.Count; p++)
        {
            if(properties[p].GetValue(row) != keys[p].Value))
            {
                match = false;
                break;
            }
        }

        if(match) return i;
    }

    return -1;
}

请记住，要使其可用，您确实需要一个更智能的比较算法，但我将把它作为练习留给读者。检查IComparable的实现将是一个良好的开端。尽管如此，无论具体的实施点是什么，这一概念都应该贯彻执行

---

请注意，这不会利用底层数据源可能实现的任何性能优化，而单列Find可以

不，不幸的是这是不可能的。虽然给定一个特定的数据源，这样的搜索可能会相当简单，但像BindingSource那样以更通用的方式进行搜索会有点不透明。首先，语法不太明显。下面是一个有点做作的解决方案：

public class Key
{
    public string PropertyName {get; set;}
    public object Value {get; set;}
}

public static int Find(this BindingSource source, params Key[] keys)
{
    PropertyDescriptor[] properties = new PropertyDescriptor[keys.Length];

    ITypedList typedList = source as ITypedList;

    if(source.Count <= 0) return -1;

    PropertyDescriptorCollection props;

    if(typedList != null) // obtain the PropertyDescriptors from the list
    {
        props = typedList.GetItemProperties(null);
    }
    else // use the TypeDescriptor on the first element of the list
    {
        props = TypeDescriptor.GetProperties(source[0]);
    }

    for(int i = 0; i < keys.Length; i++)
    {
        properties[i] = props.Find(keys[i].PropertyName, true, true); // will throw if the property isn't found
    }

    for(int i = 0; i < source.Count; i++)
    { 
        object row = source[i];
        bool match = true;

        for(int p = 0; p < keys.Count; p++)
        {
            if(properties[p].GetValue(row) != keys[p].Value))
            {
                match = false;
                break;
            }
        }

        if(match) return i;
    }

    return -1;
}

请记住，要使其可用，您确实需要一个更智能的比较算法，但我将把它作为练习留给读者。检查IComparable的实现将是一个良好的开端。尽管如此，无论具体的实施点是什么，这一概念都应该贯彻执行

---

请注意，这不会利用底层数据源可能实现的任何性能优化，而单列Find可以

另一个更简单的解决方案，以防有人遇到同样的问题。当BindingSource是DataView时，此选项有效：

MyBindingSource.Sort = "Column1,Column2"
Dim underlyingView As DataView = DirectCast(MyBindingSource.List, DataView)
Dim searchVals As New List(Of Object)
searchVals.Add("SearchString1")
searchVals.Add("SearchString2")

Dim ListIndex as Integer = underlyingView.Find(searchVals.ToArray)

If ListIndex >=0 Then
    MyBindingList.Position = ListIndex
Else
    'No matches, so what you need to do...
End If

---

另一个更简单的解决方案，以防有人遇到同样的问题。当BindingSource是DataView时，此选项有效：

MyBindingSource.Sort = "Column1,Column2"
Dim underlyingView As DataView = DirectCast(MyBindingSource.List, DataView)
Dim searchVals As New List(Of Object)
searchVals.Add("SearchString1")
searchVals.Add("SearchString2")

Dim ListIndex as Integer = underlyingView.Find(searchVals.ToArray)

If ListIndex >=0 Then
    MyBindingList.Position = ListIndex
Else
    'No matches, so what you need to do...
End If

---

这是基于上述示例的我的版本。它工作得很好

Public Class clsBSHelpers

    Public Structure Key

        Public PropertyName As String
        Public Value As Object

        Sub New(ByVal pPropertyName As String, ByVal pValue As Object)
            PropertyName = pPropertyName
            Value = pValue
        End Sub

    End Structure

    Public Shared Function Find(ByVal Source As BindingSource, ByVal ParamArray keys As Key()) As Boolean

        Dim sb As New Text.StringBuilder
        For i As Integer = 0 To keys.Length - 1
            If sb.Length > 0 Then
                sb.Append(",")
            End If
            sb.Append(keys(i).PropertyName)
        Next

        Source.Sort = sb.ToString
        Dim underlyingView As DataView = DirectCast(Source.List, DataView)
        Dim searchVals As New List(Of Object)
        For i As Integer = 0 To keys.Length - 1
            searchVals.Add(keys(i).Value)
        Next

        Dim ListIndex As Integer = underlyingView.Find(searchVals.ToArray)

        If ListIndex >= 0 Then
            Source.Position = ListIndex
            Find = True
        Else
            Find = False
            'No matches, so what you need to do...
        End If

        Return Find

    End Function

End Class

我这样称呼它：

e.Cancel = clsBSHelpers.Find(CastingBedBindingSource, _
                             New clsBSHelpers.Key("PlantID", m_PlantID), _
                             New clsBSHelpers.Key("LineBedNUmber", m_LineBedNumber))

---

希望这能帮助那些喜欢简单的人。

这是基于上述示例的我的版本。它工作得很好

Public Class clsBSHelpers

    Public Structure Key

        Public PropertyName As String
        Public Value As Object

        Sub New(ByVal pPropertyName As String, ByVal pValue As Object)
            PropertyName = pPropertyName
            Value = pValue
        End Sub

    End Structure

    Public Shared Function Find(ByVal Source As BindingSource, ByVal ParamArray keys As Key()) As Boolean

        Dim sb As New Text.StringBuilder
        For i As Integer = 0 To keys.Length - 1
            If sb.Length > 0 Then
                sb.Append(",")
            End If
            sb.Append(keys(i).PropertyName)
        Next

        Source.Sort = sb.ToString
        Dim underlyingView As DataView = DirectCast(Source.List, DataView)
        Dim searchVals As New List(Of Object)
        For i As Integer = 0 To keys.Length - 1
            searchVals.Add(keys(i).Value)
        Next

        Dim ListIndex As Integer = underlyingView.Find(searchVals.ToArray)

        If ListIndex >= 0 Then
            Source.Position = ListIndex
            Find = True
        Else
            Find = False
            'No matches, so what you need to do...
        End If

        Return Find

    End Function

End Class

我这样称呼它：

e.Cancel = clsBSHelpers.Find(CastingBedBindingSource, _
                             New clsBSHelpers.Key("PlantID", m_PlantID), _
                             New clsBSHelpers.Key("LineBedNUmber", m_LineBedNumber))

---

希望这能帮助那些喜欢简单的人。

更简单的解决方案是使用扩展方法：

var id1 = "id1";
var id2 = "id2";

var data = bindingSource1.Cast<DataModelType>().Single(r => r.ID1 == id1 && r.ID2 == id2);
bindingSource1.Position = bindingSource1.IndexOf(data);

---

更简单的解决方案是使用扩展方法：

var id1 = "id1";
var id2 = "id2";

var data = bindingSource1.Cast<DataModelType>().Single(r => r.ID1 == id1 && r.ID2 == id2);
bindingSource1.Position = bindingSource1.IndexOf(data);

---

完美。唯一的更正是这一行是ifproperties[p].GetValuerow！=键[p]。值有一个需要删除的额外值。p效果。唯一的更正是这一行是ifproperties[p].GetValuerow！=键[p]。值有一个额外的值需要删除。请添加一些解释，以帮助用户理解为什么您认为您的答案可以解决此问题。谢谢。请添加一些解释，以帮助用户理解为什么您认为您的答案可以解决问题。非常感谢。