Question

我对C＃和WPF很新，我的曝光主要是自我造成的，所以我想我可能会遗漏一些明显的东西。然而，它似乎如此显而易见，它不会在几个小时的搜索中出现。

由于我只想尝试处理，所有数据都是随意的，简单的，有点傻。

我在名为dt1的DataTable中有这些数据：

Name   Count  Date
Fred   1      12/01/13
Fred   2      12/02/13
Fred   3      12/03/13
Fred   4      12/04/13
Barney 4      12/01/13
Barney 3      12/02/13
Barney 2      12/03/13
Barney 1      12/04/13
Wilma  1      12/01/13
Wilma  2      12/02/13
Wilma  3      12/03/13
Wilma  4      12/04/13
Betty  4      12/01/13
Betty  3      12/02/13
Betty  2      12/03/13
Betty  1      12/04/13

（列分别为string，int和string）

我要做的是创建第二个DataTable，每个名称都有一行，每个日期的计数显示在一个单独的列中，因此：

Name  12/01/13  12/02/13  12/03/13  12/04/13
Fred  1         2         3         4
...

这是我用来填充第二个DataTable的代码：

DataTable dt2 = new DataTable();

//add columns for the target dates
dt2.Columns.Add("Name", typeof(string));
for (int n = 1; n < 5; n++)
{
    dt2.Columns.Add(String.Format("12/0{0}/13", n.ToString()), typeof(int));
}

DataRow pivotRow = dt2.NewRow();

foreach (DataRow row in dt1.Rows)   //step through the rows in the source table
{
    if (pivotRow[0].ToString() != row[0].ToString())   //if this is a "new" name in the data set
    {
        if (pivotRow[0].ToString() != "")  //and it's not the first row of the data set
            dt2.Rows.Add(pivotRow);  //add the row we've been working on
        pivotRow = dt2.NewRow();  //create a new row for the "next" name
        pivotRow[0] = row[0].ToString();  //add the "next" name to the name column
    }
    //match the string date stored in column 2 of the source DataTable to the column name in the target one, and put the associated int value in that column
    pivotRow[row[2].ToString()] = (int)row[1];
}
//once we've finished the whole source DataTable, add the final row to the target DataTable
dt2.Rows.Add(pivotRow);

//at this point, looking at it through the locals window everything *appears* to be peachy in dt2

GridView.ItemsSource = dt2.DefaultView;  //and here, it's all the pits.

这是DataGrid中显示的内容：

Name        12/01/13    12/02/13    12/03/13    12/04/13
Fred
Barney
Wilma
Betty

显然某些东西正在保存，因为它在行的开头保存了名称，但同样明显的是它没有保存其余的数据点。

我的头骨在敲打这个特殊的墙壁时都是糊状的，所以我决定向那些比我更了解的人寻求帮助。

非常感谢任何见解或建议。

Answer 1

如果在调试时查看输出窗口，当网格尝试显示数据时，您应该注意到一大堆绑定错误。问题是“/”字符用于解析与底层对象的绑定，因此它无法从您的视图中获取数据。

您可以通过替换 ColumnName 中的'/'字符，但将其置于标题中来实现此目的。

//add columns for the target dates
DataTable dt2 = new DataTable();
dt2.Columns.Add("Name", typeof(string));
for (int n = 1; n < 5; n++)
{                
    var dataColumn = dt2.Columns.Add(String.Format("12_0{0}_13", n), typeof (int));
    dataColumn.Caption = String.Format("12/0{0}/13", n);                
}

DataRow pivotRow = dt2.NewRow();

foreach (DataRow row in dt1.Rows)   //step through the rows in the source table
{
    if (pivotRow[0].ToString() != row[0].ToString())   //if this is a "new" name in the data set
    {
        if (pivotRow[0].ToString() != "")  //and it's not the first row of the data set
            dt2.Rows.Add(pivotRow);  //add the row we've been working on
        pivotRow = dt2.NewRow();  //create a new row for the "next" name
        pivotRow[0] = row[0].ToString();  //add the "next" name to the name column
    }
    //match the string date stored in column 2 of the source DataTable to the column name in the target one, replacing the '/', and put the associated int value in that column
    pivotRow[row[2].ToString().Replace("/", "_")] = (int)row[1];
}
//once we've finished the whole source DataTable, add the final row to the target DataTable
dt2.Rows.Add(pivotRow);

Answer 2

这是一个适用于原始数据表中任意日期和任意名称顺序的解决方案：

DataTable dt2 = new DataTable();
dt2.Columns.Add("Name", typeof(string));

IEnumerable<DateTime> distinctDates = dt1.AsEnumerable().Select(row => (DateTime)row["Date"]).Distinct().OrderBy(date => date);
foreach (var distinctDate in distinctDates)
{
    dt2.Columns.Add(distinctDate.ToString("MM__dd__yy", CultureInfo.InvariantCulture), typeof(int));
}

IEnumerable<string> distinctNames = dt1.AsEnumerable().Select(row => (string)row["Name"]).Distinct();
foreach (var distinctName in distinctNames)
{
    DataRow outputRow = dt2.NewRow();
    outputRow["Name"] = distinctName;

    IEnumerable<Tuple<int, DateTime>> inputRowsForName = dt1.AsEnumerable()
        .Where(row => (string)row["Name"] == distinctName)
        .Select(row => new Tuple<int, DateTime>((int)row["Count"], (DateTime)row["Date"]));

    foreach (var inputRowForName in inputRowsForName)
    {
        string columnName = inputRowForName.Item2.ToString("MM__dd__yy", CultureInfo.InvariantCulture);
        outputRow[columnName] = inputRowForName.Item1;
    }
    dt2.Rows.Add(outputRow);
}

GridView.ItemsSource = dt2.DefaultView;

DataTable不保留附加值

2 个答案: