Question

我有两个组合框（表单 1 中的组合框 1 和表单 2 中的组合框 2）。我需要导入一个 excel 文件，并且 combobox1 获取工作表名称。然后在 form2 中（我不想再次导入同一个文件）我有 combobox2，它也有来自 combobox1 的相同工作表名称。

我试过了，但我得到了 NULLFUNCTION 表达式的错误（附加信息：对象引用没有设置为对象的实例）。

 using (OpenFileDialog openFileDialog = new OpenFileDialog() { Filter = "Excel 97-2003 Workbook|*.xls|Excel Workbook|*.xlsx |fichiers Textes (*.txt)|*.txt|fichiers CSV (*.csv)|*.csv|tous les fichiers (*.*)|*.*" })
            {
                if (openFileDialog.ShowDialog() == DialogResult.OK)
                {
                    TextBox_Emplacement.Text = openFileDialog.FileName;
                    using (var stream = File.Open(openFileDialog.FileName, FileMode.Open, FileAccess.Read))
                    {
                        using (IExcelDataReader reader = ExcelReaderFactory.CreateReader(stream))
                        {
                            DataSet result = reader.AsDataSet(new ExcelDataSetConfiguration()
                            {
                                ConfigureDataTable = (_) => new ExcelDataTableConfiguration() { UseHeaderRow = true }
                            });
                            dataTableCollection = result.Tables; 
                            dataTableCollection1 = result.Tables;
                            sheet.Items.Clear();
                            //cp.radDropDownList1.Items.Clear();
                            foreach (DataTable table in dataTableCollection)
                                sheet.Items.Add(table.TableName);//add sheet to combobox

                           **Form_Copie cp1 = (Form_Copie)Application.OpenForms["Form_Copie"];
                           foreach (DataTable table in dataTableCollection)
                              cp1.radDropDownList1.Items.Add(table.TableName);//add sheet to combobox**

Answer 1

有几种方法可以做到这一点。重载构造函数是一个好方法，但是对每个控件执行此操作会很快变得令人生畏和混乱。如果您想为多个控件执行此操作，我建议使用包含绑定属性（例如 System.ComponentModel.BindingList 和/或 System.Forms.Binding）作为每个表单中的字段的模型。然后重载构造函数并通过模型类传入绑定。

public class BindingModel {
    public property BindingList<string> ComboBoxBinding {get;set;}
    ... other binding/non-binding properties ...
}

public class Form1{
    private BindingModel _bindingModel = new _bindingModel();

    private void Form1_Shown(object sender, EventArgs e) {
        this.ComboBox1.DataSource = _bindingModel.ComboBoxBinding;
        this.ComboBox1.DataMember = "";

        // the add would go in your excel method
        _bindingModel.ComboBoxBinding.Add("Item 1");
    }

    private void btnOpenForm2_Click(object sender, EventArgs e) {
        var frm = new Form2(_bindingModel);
        frm.Show();
        this.Close();
    }
}

public class Form2{
    private BindingModel _bindingModel = new _bindingModel();
    
    public void Form2(BindingModel bindingModel){
        this._bindingModel = bindingModel;
    }

    // Once the form is shown bind the ComboBox and it will populate the values
    private void Form2_Shown(object sender, EventArgs e){
        this.ComboBox1.DataSource = _bindingModel.ComboBoxBinding;
        this.ComboBox1.DataMember = "";
    }
}

或者，可以在调用表单中设置控件项：

public class Form1{
    private void btnOpenForm2_Click(object sender, EventArgs e) {
        var frm = new Form2();
        for(int i = 0; i < this.ComboBox1.Count - 1; i++){
            frm.ComboBox1.Items.Add(ComboBox1.Items[i]);
        }
        frm.Show();
        this.Close();
    }
}

如何在form2中将combobox1项从form1传递到combobox2

1 个答案: