问题
Is there a predefined or "easy" method of writing a datatable to a text file or TextBox Control (With monospace font) such as DataTable.Print():
Column1| Column2| --------|--------| v1| v2| v3| v4| v5| v6|
Edit
Here's an initial version (vb.net) - in case anyone is interested or wants to build their own:
Public Function BuildTable(ByVal dt As DataTable) As String
Dim result As New StringBuilder
Dim widths As New List(Of Integer)
Const ColumnSeparator As Char = "|"c
Const HeadingUnderline As Char = "-"c
' determine width of each column based on widest of either column heading or values in that column
For Each col As DataColumn In dt.Columns
Dim colWidth As Integer = Integer.MinValue
For Each row As DataRow In dt.Rows
Dim len As Integer = row(col.ColumnName).ToString.Length
If len > colWidth Then
colWidth = len
End If
Next
widths.Add(CInt(IIf(colWidth < col.ColumnName.Length, col.ColumnName.Length + 1, colWidth + 1)))
Next
' write column headers
For Each col As DataColumn In dt.Columns
result.Append(col.ColumnName.PadLeft(widths(col.Ordinal)))
result.Append(ColumnSeparator)
Next
result.AppendLine()
' write heading underline
For Each col As DataColumn In dt.Columns
Dim horizontal As String = New String(HeadingUnderline, widths(col.Ordinal))
result.Append(horizontal.PadLeft(widths(col.Ordinal)))
result.Append(ColumnSeparator)
Next
result.AppendLine()
' write each row
For Each row As DataRow In dt.Rows
For Each col As DataColumn In dt.Columns
result.Append(row(col.ColumnName).ToString.PadLeft(widths(col.Ordinal)))
result.Append(ColumnSeparator)
Next
result.AppendLine()
Next
Return result.ToString()
End Function
回答1:
No, there isn't. You will have to do the formatting yourself, or find a third-party library that will do this yourself.
回答2:
I recommend you check out my article DataTable Formatter.
My DataTableFormatter class contains methods for formatting DataTables as character-based tables (your requirement), HTML tables, or flow document tables.
You can download the project containing the class from my website, but for convenience I will post the code here.
/// <summary>
/// Gets a string representation of the <see cref="System.Data.DataTable" />.
/// </summary>
/// <remarks>The string representation should be displayed with a monospaced font.</remarks>
public static string GetStringRepresentation(DataTable dataTable)
{
if (dataTable == null)
throw new ArgumentNullException("'dataTable' cannot be null.");
StringWriter representationWriter = new StringWriter();
// First, set the width of every column to the length of its largest element.
int[] columnWidths = new int[dataTable.Columns.Count];
for (int columnIndex = 0; columnIndex < dataTable.Columns.Count; columnIndex++)
{
int headerWidth = dataTable.Columns[columnIndex].ColumnName.Length;
int longestElementWidth = dataTable.AsEnumerable()
.Select((row) => row[columnIndex].ToString().Length)
.Max();
columnWidths[columnIndex] = Math.Max(headerWidth, longestElementWidth);
}
// Next, write the table
// Write a horizontal line.
representationWriter.Write("+-");
for (int columnIndex = 0; columnIndex < dataTable.Columns.Count; columnIndex++)
{
for (int i = 0; i < columnWidths[columnIndex]; i++)
representationWriter.Write("-");
representationWriter.Write("-+");
if (columnIndex != dataTable.Columns.Count - 1)
representationWriter.Write("-");
}
representationWriter.WriteLine(" ");
// Print the headers
representationWriter.Write("| ");
for (int columnIndex = 0; columnIndex < dataTable.Columns.Count; columnIndex++)
{
string header = dataTable.Columns[columnIndex].ColumnName;
representationWriter.Write(header);
for (int blanks = columnWidths[columnIndex] - header.Length; blanks > 0; blanks--)
representationWriter.Write(" ");
representationWriter.Write(" | ");
}
representationWriter.WriteLine();
// Print another horizontal line.
representationWriter.Write("+-");
for (int columnIndex = 0; columnIndex < dataTable.Columns.Count; columnIndex++)
{
for (int i = 0; i < columnWidths[columnIndex]; i++)
representationWriter.Write("-");
representationWriter.Write("-+");
if (columnIndex != dataTable.Columns.Count - 1)
representationWriter.Write("-");
}
representationWriter.WriteLine(" ");
// Print the contents of the table.
for (int row = 0; row < dataTable.Rows.Count; row++)
{
representationWriter.Write("| ");
for (int column = 0; column < dataTable.Columns.Count; column++)
{
representationWriter.Write(dataTable.Rows[row][column]);
for (int blanks = columnWidths[column] - dataTable.Rows[row][column].ToString().Length;
blanks > 0; blanks--)
representationWriter.Write(" ");
representationWriter.Write(" | ");
}
representationWriter.WriteLine();
}
// Print a final horizontal line.
representationWriter.Write("+-");
for (int column = 0; column < dataTable.Columns.Count; column++)
{
for (int i = 0; i < columnWidths[column]; i++)
representationWriter.Write("-");
representationWriter.Write("-+");
if (column != dataTable.Columns.Count - 1)
representationWriter.Write("-");
}
representationWriter.WriteLine(" ");
return representationWriter.ToString();
}
The method GetStringRepresentation(DataTable) gives results such as this
+------------------+----------------+-------------------+ | Item | Units in Stock | Unit Price | +------------------+----------------+-------------------+ | Drilling machine | 1000 | $1,000,000 | | Backpack | 320 | $24 | | Chocolate bar | 100000 | $2.00000000000000 | +------------------+----------------+-------------------+
I should admit that this table style is cheated from the MySQL command line client.
回答3:
You could use a DataTableReader:
public static string PrintTable(this DataTable dt)
{
DataTableReader dtReader = dt.CreateDataReader();
StringBuilder result = new StringBuilder();
while (dtReader.Read())
{
for (int i = 0; i < dtReader.FieldCount; i++)
{
result.AppendFormat("{0} = {1}",
dtReader.GetName(i).Trim(),
dtReader.GetValue(i).ToString().Trim());
}
result.AppendLine();
}
dtReader.Close();
return result.ToString();
}
来源:https://stackoverflow.com/questions/691363/printing-a-datatable-to-textbox-textfile-in-net