用";“分隔符从CsvReader中使用LumenWorks

Question

我对来自CsvReader的LumenWorks有两个小问题。

首先，我的*.csv文件有一个;分隔符。没什么大不了的，我只需更改读取器中的分隔符属性，但实际上要复杂一些，因为标头也以;结尾，而不是行。

例如：

Column1;Column2;Column3;
1;Michael;Page
2;Michael;Jackson
...

有什么办法向读者表明吗？

第二个问题是如何动态选择要导入的列？

我的代码如下所示：

Public Sub ImportCSV2Data(ByVal filename As String, ByRef gridToShow As GridControl, ByVal column2Import() As Integer)
    Dim csvCopy As CachedCsvReader = New CachedCsvReader(New StreamReader(filename), True, ";"c)
    Dim processedCopy = csvCopy.Select(Function(showColumn) New With{.SAPNo = column(0),.CCode = column(2)})

    gridToShow.DataSource = processedCopy
End Sub

但是，如何使所选列取决于column2Import中的值？

谢谢

Answer 1

依赖CSVReader并不是一件坏事，但是如果您有特殊的需求，也许更容易依赖传统的StreamReader，而不是花时间进行所需的修改。样本代码：

 Dim sr As System.IO.StreamReader = New System.IO.StreamReader("target CSV file path")
 Dim line As String

 'Adapt this code to retrieve the column names from the file itself or from other source
 Dim getColumnNames As Boolean = True
 Dim columnNames() As String = Nothing

 Do
     line = sr.ReadLine()
     If (line IsNot Nothing) Then
         if(line.Contains(";")) then
             If (columnNames Is Nothing And getColumnNames) Then
                 columnNames = line.Split(";")
             Else
                 Dim curRowVals() As String = line.Split(";")
                 'All the row values
             End If
         End If
     End If
 Loop Until line Is Nothing

Answer 2

要回答“第二个问题”，如何选择列的子集：

Dim result As IEnumerable(Of String()) = csvCopy.
    Select(Function(fields) fields.Where(Function(f, i) column2Import.Contains(i))
                                  .ToArray()) 

Answer 3

在睡了一个好觉之后，我有了这样的想法：

Dim csvCopy As CachedCsvReader = New CachedCsvReader(New StreamReader(filename), True, ";"c)
csvCopy.MissingFieldAction = MissingFieldAction.ReplaceByEmpty

Dim headers() As String = csvCopy.GetFieldHeaders
For Each column As Integer In column2Import
    datatable.Columns.Add(headers(column))
Next
While csvCopy.ReadNextRecord()
    Dim csvRow As DataRow = datatable.NewRow
    Dim i As Integer = 0
    For Each column As Integer In column2Import
        csvRow(i) = csvCopy(column)
        i += 1
    Next
    datatable.Rows.Add(csvRow)
End While

csvCopy.MissingFieldAction = MissingFieldAction.ReplaceByEmpty解决了我的第二个问题，其余的解决了第一个问题