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如何在WinForms中绑定多对多关系?

dataset ado.net data-binding winforms c#

Ron Inbar · 技术社区 · 6 年前

我有以下数据集:

这个 Product 和 Part 可以使用以下DataGridView编辑表:

当用户双击产品网格中的一行时,将打开以下表单:

左栏应列出与此产品相关的零件。右栏应列出所有其他部分。使用(<<和>&燃气轮机;按钮,用户应能够选择属于当前产品的部件。

我在一对多关系中也做过类似的事情,效果很好。代码如下:

public partial class ProductPartsForm : Form
{
    private int _productID;
    private DataSet1 _data;

    public ProductPartsForm(DataSet1 data, DataRowView productRowView)
    {
        var productRow = (DataSet1.ProductRow)productRowView.Row;
        _productID = productRow.ID;
        _data = data;
        InitializeComponent();
        productBindingSource.DataSource = productRowView;
        assignedPartBindingSource.DataSource = productBindingSource;
        assignedPartBindingSource.DataMember = "FK_Product_Part";
        assignedPartsListBox.DisplayMember = "Name";
        unassignedPartBindingSource.DataSource = _data;
        unassignedPartBindingSource.DataMember = "Part";
        unassignedPartsListBox.DisplayMember = "Name";
        unassignedPartBindingSource.Filter = $"isnull(ProductID, 0) = 0";
    } 

    private void assignButton_Click(object sender, EventArgs e)
    {
        var partRowView = (DataRowView)unassignedPartBindingSource.Current;
        var partRow = (DataSet1.PartRow)partRowView.Row;
        var productRowView = (DataRowView)productBindingSource.Current;
        var productRow = (DataSet1.ProductRow)productRowView.Row;
        partRow.ProductRow = productRow;
        UpdateUI();
    }

    private void unassignButton_Click(object sender, EventArgs e)
    {
        var partRowView = (DataRowView)assignedPartBindingSource.Current;
        var partRow = (DataSet1.PartRow)partRowView.Row;
        partRow.SetProductIDNull();
        UpdateUI();
    }

    private void UpdateUI()
    {
        assignedPartsListBox.Refresh();
        unassignedPartsListBox.Refresh();
        assignButton.Enabled = unassignedPartsListBox.Items.Count > 0;
        unassignButton.Enabled = assignedPartsListBox.Items.Count > 0;
    }
}

在多对多关系中,有两件事我无法完成:

左列不显示零件的名称。它应该显示小写字母,如右列;相反,它显示字符串 System.Data.DataRowView .我想通过某种查找来解决这个问题,但我不知道如何解决。
当您按下 << ,选定零件将保留在右列上,而不是移动到左列。如果你试着按 << 同样,对于相同的零件,您会得到以下错误:

系统数据ConstraintException:“Column”ProductID,PartID“被约束为唯一。值“-4,-3”已存在。”

(这是可以理解的)。我认为这可以通过使用过滤器表达式来修复,但我不确定如何编写它,以及如何在每次更改后自动更新正确的列。

有没有人做过类似的事情,能帮我指出正确的方向?

1 回复 | 直到 6 年前

Ron Inbar 6 年前

这是我最后想到的。关键功能是 UpdateFilters ,它创建分配给当前产品的零件ID列表,然后使用 IN 和 NOT IN 操作员。

public partial class ProductPartsForm : Form
{
    private int _productID;
    private DataSet1 _data;

    public ProductPartsForm(DataSet1 data, DataRowView productRowView)
    {
        var productRow = (DataSet1.ProductRow)productRowView.Row;
        _productID = productRow.ID;
        _data = data;
        InitializeComponent();
        productBindingSource.DataSource = productRowView;
        assignedPartBindingSource.DataSource = _data;
        assignedPartBindingSource.DataMember = "Part";
        assignedPartsListBox.DisplayMember = "Name";
        unassignedPartBindingSource.DataSource = _data;
        unassignedPartBindingSource.DataMember = "Part";
        unassignedPartsListBox.DisplayMember = "Name";
    }

    private void ProductPartsForm_Load(object sender, EventArgs e)
    {
        UpdateFilters();
        UpdateUI();
    }

    private void assignButton_Click(object sender, EventArgs e)
    {
        var partRowView = (DataRowView)unassignedPartBindingSource.Current;
        var partRow = (DataSet1.PartRow)partRowView.Row;
        var productRowView = (DataRowView)productBindingSource.Current;
        var productRow = (DataSet1.ProductRow)productRowView.Row;
        _data.ProductPart.AddProductPartRow(productRow, partRow);
        UpdateFilters();
        UpdateUI();
    }

    private void unassignButton_Click(object sender, EventArgs e)
    {
        var partRowView = (DataRowView)assignedPartBindingSource.Current;
        var partRow = (DataSet1.PartRow)partRowView.Row;
        var productPartRow = _data.ProductPart
            .Single(pp => pp.ProductID == _productID && pp.PartID == partRow.ID);
        _data.ProductPart.RemoveProductPartRow(productPartRow);
        UpdateFilters();
        UpdateUI();
    }

    private void UpdateFilters()
    {
        var assignedIds = _data.ProductPart
            .Where(pp => pp.ProductID == _productID)
            .Select(pp => pp.PartID.ToString());
        if (assignedIds.Any())
        {
            assignedPartBindingSource.Filter = $"ID IN ({string.Join(",", assignedIds)})";
            unassignedPartBindingSource.Filter = $"ID NOT IN ({string.Join(",", assignedIds)})";
        }
        else
        {
            assignedPartBindingSource.Filter = "FALSE";
            unassignedPartBindingSource.RemoveFilter();
        }
    }

    private void UpdateUI()
    {
        assignedPartsListBox.Refresh();
        unassignedPartsListBox.Refresh();
        assignButton.Enabled = unassignedPartsListBox.Items.Count > 0;
        unassignButton.Enabled = assignedPartsListBox.Items.Count > 0;
    }
}