1

我正在使用实体框架，我像填充网格控件一样；

  Models.dbContext ent = new Models.dbContext();      
  ent.Locations.Load();
  gridControl1.DataSource = ent.Locations.Local.ToBindingList();

然后我试图得到像这样的表名；

 DataTable dt = ((DataView)gridview1.DataSource).Table;
 Messagebox.Show(dt.TableName);

它给了我错误：无法将“System.Data.Entity.Internal.ObservableBackedBindingList`1[Models.Location]”类型的对象转换为“System.Data.DataView”。

为什么会发生这种情况？我的代码有什么问题？

4

1 回答 1

1

您可以尝试为 DataGridView 创建一个扩展方法，以便将其转换为 DataTable：

public static class DataGridViewExtension 
{
    // Method for: DataGridView to DataTable conversion
    public static DataTable ToTable(this DataGridView dataGridView, bool onlyVisible=false)
    {
        // Identifiers used are:
        int rowCount = dataGridView.Rows.Count;
        var dataTable = new DataTable();
        var columnTypes = new Dictionary<string, Type>();
        var rowItems = new List<object>();

        // Get the column names and types
        columnTypes = dataGridView.ColumnTypes(onlyVisible);

        // Setup the DataTable column structure
        dataTable.SetupColumns(columnTypes);

        // Get the rows of the DataGridView
        foreach (DataGridViewRow row in dataGridView.Rows)
        {
            // Get the row as a list to give to the table
            rowItems = row.ToList(onlyVisible);
            // Give the row items to the DataTable
            dataTable.Rows.Add(rowItems.ToArray());
        }

        // Return the data table
        return dataTable;
    }
}

我又做了 3 个扩展，它们是：

public static class DataGridViewExtension 
{
    // Class for: Getting the column names with column types from a DataGridView
    public static Dictionary<string, Type> ColumnTypes(this DataGridView dataGridView, 
        bool onlyVisible=false)
    {
        // Identifiers used are:
        var types = new Dictionary<string, Type>();

        // Go through the columns of the view
        foreach (DataGridViewColumn column in dataGridView.Columns)
        {
            if (onlyVisible == true && column.Visible == true)
            {
                types[column.HeaderText] = column.ValueType;
            }
            else if (!onlyVisible)
            {
                types[Column.HeaderText] = column.ValueType;
            }
        }

        // Return the results
        return types;
    }
}

public static class DataGridViewRowExtension
{
    // Method for: Returning the cells of a row as a List<object>
    public static List<object> ToList(this DataGridViewRow dataGridViewRow,
        bool onlyVisible= false)
    {
        // Identifiers used are:
        var objectList = new List<object>();

        // Go through the row and add the items to the list
        foreach (DataGridViewCell cell in dataGridViewRow.Cells)
        {
            if (onlyVisible == true && cell.Visible == true)
            {
                objectList.Add(cell.Value);
            }
            else if (!onlyVisible)
            {
                objectList.Add(cell.Value);
            }
        }

        // Return the list
        return objectList;
    }
}

public static class DataTableExtension
{
    // Method for: Setting up the column structure of a data table using a dictionary holding column name with data type
    public static void SetupColumns(this DataTable dataTable,
        Dictionary<string, Type> columns)
    {
        // Identifiers used are:
        int columnCount = columns.Count;

        // Set up the structure
        foreach (KeyValuePair<string, Type> column in columns)
        {
            dataTable.Columns.Add(column.Key, column.Value);
        }
    }
}

尽管这是一种迂回的方式，但您至少可以执行以下操作

string tableName = dataGridView.ToTable().TableName;

当然，这种方式很乏味，但是如果您需要这些扩展来做其他事情，它会在您赶时间和有用的情况下起作用。

于 2018-08-06T13:27:33.827 回答