DataGridViewComboBoxCell 已填充但不会显示内容答案

【问题标题】：DataGridViewComboBoxCell populated but will not display contentDataGridViewComboBoxCell 已填充但不会显示内容
【发布时间】：2019-07-08 19:54:36
【问题描述】：

我正在尝试为我设置为 ComboBoxcolumn 的 datagridview 列之一动态设置自定义下拉列表。当我运行我的应用程序时，我看到我的单元格中有值。但是，我没有看到 UI 中弹出任何值。

private void CustomComboBoxColumns(string filter)
    {
        DataGridViewComboBoxColumn ComboBoxColumn = new DataGridViewComboBoxColumn();
        DataTable dt;
        ComboBoxColumn.HeaderText = "category";
        ComboBoxColumn.DataPropertyName = "category";
        ComboBoxColumn.ReadOnly = false;
        ComboBoxColumn.MaxDropDownItems = 100;
        ComboBoxColumn.AutoSizeMode = DataGridViewAutoSizeColumnMode.DisplayedCells;
        ComboBoxColumn.FlatStyle = FlatStyle.Flat;
        ComboBoxColumn.ValueMember = "category";
        ComboBoxColumn.DisplayMember = "category";
        _iprDataGridView.Columns.Insert(16, ComboBoxColumn);
        for (int i = 0; i < _iprDataGridView.Rows.Count; i++)
        {
            dt = GetDataForCategory(filter);
            ((DataGridViewComboBoxCell)_iprDataGridView.Rows[i].Cells[16]).DataSource = dt;
        }
    }

    private DataTable GetDataForCategory(string filter)
    {
        DbConnection db = new DbConnection();
        string connString = db.BuildConnectionString();
        DataTable dt = new DataTable();
        DataSet ds = new DataSet();
        string query = "Select category from cd_category where category like '%" + filter + "%' order by category";
        using (SqlConnection conn = new SqlConnection(connString))
        {
            if (conn.State == ConnectionState.Closed)
            {
                conn.Open();
            }

            SqlDataAdapter da = new SqlDataAdapter(query, conn);
            da.Fill(ds, "category");
            dt = ds.Tables["category"];
            da.Dispose();
            conn.Close();
        }
        return dt;
    }

当我附加调试器并检查 ((DataGridViewComboBoxCell)_iprDataGridView.Rows[i].Cells[16]).DataSource = dt;我的项目集合中有一些值，它只是不会显示它。

这里有更多关于如何设置 datagridview 的代码。

_iprDataGridView.DataSource = _dbHelper.Select(queryBuild.ToString(), parameters, dbConnection);

            if (_iprDataGridView.DataSource == null) return;
            // In order to display and match the PIR table values, that are requried to be in
            // a comboBox menu, we need to remove the columns that have been populated and then
            // re-add them as comboBoxs
            ConfigureDataGridView();
            ConfigureComboBoxColumns();
            ConfigureTextBoxColumns();

我正在考虑在 ConfigureTextBoxColumns() 之后我将创建我的方法，该方法将遍历 datagridview 并创建一个新的类别 comboboxcolumn 并根据另一个列值插入一个新的 comboboxcell。

这是如何为 datagridview 生成列的代码

private void ConfigureComboBoxColumns()
    {
        DataGridViewHelper dataGridViewHelper = new DataGridViewHelper();
        // Columns being converted to comboboxcolumns must be removed, created, and re-inserted
        dataGridViewHelper.RemoveColumns(ref _iprDataGridView,
                                         Columns.severity.ToString(),
                                         Columns.phase.ToString(),
                                         Columns.app.ToString(),
                                         Columns.project.ToString(),
                                         Columns.acceptancePeriod.ToString(),
                                         Columns.classConfirmed.ToString(),
                                         Columns.oncall.ToString(),
                                         Columns.warranty.ToString(),
                                         Columns.release.ToString(),
                                         Columns.category.ToString(),
                                         Columns.ticketType.ToString());

        DataGridViewComboBoxColumn comboBoxColumn = dataGridViewHelper.CreateComboBoxColumn(Columns.severity.ToString());
        comboBoxColumn.ValueType = typeof(int);
        string query = IPRDetailsConstants.SELECT_SEVERITY + IPRDetailsConstants.SEVERITY_COL;
        dataGridViewHelper.SetComboBoxChoicesDataSource(ref comboBoxColumn, Columns.severity.ToString(), query, dbConnection);
        _iprDataGridView.Columns.Insert((int)Columns.severity, comboBoxColumn);

        comboBoxColumn = dataGridViewHelper.CreateComboBoxColumn(Columns.phase.ToString());
        query = IPRDetailsConstants.SELECT_PHASE + IPRDetailsConstants.PHASE_COL;
        dataGridViewHelper.SetComboBoxChoicesDataSource(ref comboBoxColumn, Columns.phase.ToString(), query, dbConnection);
        _iprDataGridView.Columns.Insert((int)Columns.phase, comboBoxColumn);

        comboBoxColumn = dataGridViewHelper.CreateComboBoxColumn(Columns.app.ToString());
        query = IPRDetailsConstants.SELECT_APP + IPRDetailsConstants.APP_COL;
        dataGridViewHelper.SetComboBoxChoicesDataSource(ref comboBoxColumn, Columns.app.ToString(), query, dbConnection);
        _iprDataGridView.Columns.Insert((int)Columns.app, comboBoxColumn);

        comboBoxColumn = dataGridViewHelper.CreateComboBoxColumn(Columns.project.ToString());
        bool activeProjectsOnly = bool.Parse(ConfigurationManager.AppSettings.Get("ActiveProjectsOnly"));
        query = IPRDetailsConstants.SELECT_PROJECT + (activeProjectsOnly ? IPRDetailsConstants.PROJECT_COL_ACTIVE : IPRDetailsConstants.PROJECT_COL);
        dataGridViewHelper.SetComboBoxChoicesDataSource(ref comboBoxColumn, Columns.project.ToString(), query, dbConnection);
        _iprDataGridView.Columns.Insert((int)Columns.project, comboBoxColumn);

        comboBoxColumn = dataGridViewHelper.CreateComboBoxColumn(Columns.acceptancePeriod.ToString());
        comboBoxColumn.HeaderText = Resources.IprDetails_ConfigureComboBoxColumns_ap;
        comboBoxColumn.HeaderCell.ToolTipText = "acceptancePeriod";
        dataGridViewHelper.SetComboBoxChoicesStatic(ref comboBoxColumn, Columns.acceptancePeriod.ToString(), Resources.Y, Resources.N, Resources.S, Resources.X);
        _iprDataGridView.Columns.Insert((int)Columns.acceptancePeriod, comboBoxColumn);

        comboBoxColumn = dataGridViewHelper.CreateComboBoxColumn(Columns.classConfirmed.ToString());
        comboBoxColumn.HeaderText = Resources.IprDetails_ConfigureComboBoxColumns_cc;
        comboBoxColumn.HeaderCell.ToolTipText = "classConfirmed";
        dataGridViewHelper.SetComboBoxChoicesStatic(ref comboBoxColumn, Columns.classConfirmed.ToString(), Resources.Y, Resources.N, Resources.X);
        _iprDataGridView.Columns.Insert((int)Columns.classConfirmed, comboBoxColumn);

        comboBoxColumn = dataGridViewHelper.CreateComboBoxColumn(Columns.oncall.ToString());
        comboBoxColumn.HeaderText = Resources.IprDetails_ConfigureComboBoxColumns_oc;
        comboBoxColumn.HeaderCell.ToolTipText = "onCall";
        dataGridViewHelper.SetComboBoxChoicesStatic(ref comboBoxColumn, Columns.oncall.ToString(), Resources.Y, Resources.N, Resources.X);
        _iprDataGridView.Columns.Insert((int)Columns.oncall, comboBoxColumn);

        comboBoxColumn = dataGridViewHelper.CreateComboBoxColumn(Columns.warranty.ToString());
        comboBoxColumn.HeaderText = Resources.IprDetails_ConfigureComboBoxColumns_w;
        comboBoxColumn.HeaderCell.ToolTipText = "warranty";
        dataGridViewHelper.SetComboBoxChoicesStatic(ref comboBoxColumn, Columns.warranty.ToString(), Resources.Y, Resources.N, Resources.X);
        _iprDataGridView.Columns.Insert((int)Columns.warranty, comboBoxColumn);

        comboBoxColumn = dataGridViewHelper.CreateComboBoxColumn(Columns.ticketType.ToString());
        comboBoxColumn.HeaderText = Resources.IprDetails_ConfigureComboBoxColumns_tt;
        comboBoxColumn.HeaderCell.ToolTipText = "ticketType";
        dataGridViewHelper.SetComboBoxChoicesStatic(ref comboBoxColumn, Columns.ticketType.ToString(), "I", "P", "R", "K", "Q");
        _iprDataGridView.Columns.Insert((int)Columns.ticketType, comboBoxColumn);

        comboBoxColumn = dataGridViewHelper.CreateComboBoxColumn(Columns.release.ToString());
        bool activeReleasesOnly = bool.Parse(ConfigurationManager.AppSettings.Get("ActiveReleasesOnly"));
        query = IPRDetailsConstants.SELECT_RELEASE + (activeReleasesOnly ? IPRDetailsConstants.RELEASE_COL_ACTIVE : IPRDetailsConstants.RELEASE_COL);
        dataGridViewHelper.SetComboBoxChoicesDataSource(ref comboBoxColumn, Columns.release.ToString(), query, dbConnection);
        _iprDataGridView.Columns.Insert((int)Columns.release, comboBoxColumn);

        /*
        comboBoxColumn = dataGridViewHelper.CreateComboBoxColumn(Columns.category.ToString());
        query = IPRDetailsConstants.SELECT_CATEGORY + IPRDetailsConstants.CATEGORY_COL;
        dataGridViewHelper.SetComboBoxChoicesDataSource(ref comboBoxColumn, Columns.category.ToString(), query, dbConnection);
        _iprDataGridView.Columns.Insert((int)Columns.category, comboBoxColumn);
        */

    }

我注释掉了他们的专栏，以便插入我自己的类别。我正在更新这个不是我开发的应用程序。

【问题讨论】：

不清楚你想做什么。您是否希望“全部”列中的所有组合框都具有“相同的值”，还是希望每个组合框具有不同的值？这是两个不同的东西。通过设置“DataGridViewComboBoxColumns”DataSource. 让它们都相同是相当直接的，这将设置所有行的值相同，包括任何新行。
将“每个”单元格设置为自己的DataGridViewComboBoxCell 需要您做更多的工作。这将包括每次添加新行时填充组合框。我猜这就是你所看到的。添加新行时，我没有看到 RowsAdded 事件来填充组合框。
是的，所以我将每个单元格设置为自己的 DataGridViewComboBoxCell，前一个人为整个列生成了一个使用相同组合框单元格的列，然后在绑定 datagridview 后插入。我只是想更新一列，以便每个单元格都有自己的组合框单元格。
根据我的测试，发布的代码按预期工作。除了最后一个“新”行之外，我可以看到所有行上的组合框值。我猜还有其他事情正在发生。由于不知道您在每个组合框中放入“什么”项目，我只能假设它们完全不同。
CustomComboBoxColumn 方法将组合列添加到网格中，然后循环遍历网格中的所有行以设置每个组合框。如果用户“添加”一个新行，那么删除/重新添加组合框列然后再次遍历所有行是没有意义的？ “如何”确定每个组合框中的项目？我们可以看到一个“过滤器”字符串，它根据该字符串获取值，但是，“过滤器字符串”来自哪里？

标签： c# winforms

【解决方案1】：

您似乎正在尝试将数据绑定到控件。设置源后，您必须绑定它。请参阅我所做的编辑。此链接提供更多信息和示例 https://support.microsoft.com/en-us/help/307860/asp-net-data-binding-overview

    private void CustomComboBoxColumns(string filter)
        {
            DataGridViewComboBoxColumn ComboBoxColumn = new DataGridViewComboBoxColumn();
            DataTable dt;
            ComboBoxColumn.HeaderText = "category";
            ComboBoxColumn.DataPropertyName = "category";
            ComboBoxColumn.ReadOnly = false;
            ComboBoxColumn.MaxDropDownItems = 100;
            ComboBoxColumn.AutoSizeMode = DataGridViewAutoSizeColumnMode.DisplayedCells;
            ComboBoxColumn.FlatStyle = FlatStyle.Flat;
            ComboBoxColumn.ValueMember = "category";
            ComboBoxColumn.DisplayMember = "category";
            _iprDataGridView.Columns.Insert(16, ComboBoxColumn);
            for (int i = 0; i < _iprDataGridView.Rows.Count; i++)
            {
                dt = GetDataForCategory(filter);
             ((DataGridViewComboBoxCell)_iprDataGridView.Rows[i].Cells[16]).DataSource = dt;
             ((DataGridViewComboBoxCell)_iprDataGridView.Rows[i].Cells[16]).DataBind(); //this edit
            }
        }

我也强烈建议学习使用参数化查询来防止 sql 注入

【讨论】：

DataGridViewComboBoxCell 不包含定义.DataBind()。也是的，我之前使用过参数化查询，但为了解决问题，我只是使用这条路线。