如何使用 ExcelDataReader 从文件中删除空单元格和行？

Question

我正在使用ExcelDataReader 读取 excel 文件，但正在处理的文件有 16k 列和 1200 条记录。在这之间只有 52 列被填充，其他都是空的，所以我想删除带有行的空列。

试过了：

var dataset = reader.AsDataSet(new ExcelDataSetConfiguration() {
    ConfigureDataTable = _ => new ExcelDataTableConfiguration() {
        FilterRow = rowReader => rowReader.Depth != 0
    }
});

感谢您的帮助

Answer 1

AFAIK，没有任何简单的方法可以过滤空列或行，我最好的尝试是：

// use ExcelDataTableConfiguration.FilterRow to filter empty rows
FilterRow = rowReader =>
{
    var hasData = false;
    for (var i = 0; i < rowReader.FieldCount; i++)
    {
        if (rowReader[i] == null || string.IsNullOrEmpty(rowReader[i].ToString()))
        {
            continue;
        }

        hasData = true;
        break;
    }

    return hasData;
},
// use ExcelDataTableConfiguration.FilterColumn to filter empty columns
FilterColumn = (rowReader, colIndex) =>
{
    var hasData = false;
    rowReader.Reset();

    // this will skip first row as it is name of column
    rowReader.Read();

    while (rowReader.Read())
    {
        if (rowReader[colIndex] == null || 
            string.IsNullOrEmpty(rowReader[colIndex].ToString()))
        {
            continue;
        }

        hasData = true;
        break;
    }

    // below codes do a trick!
    rowReader.Reset();
    rowReader.Read();

    return hasData;
}

在FilterRow 或FilterColumn 中使用IExcelDataReader 参数是邪恶的！
我认为主要reader 和每个rowReader 都引用了一个对象！所以你应该始终知道如何使用它们，正如你所看到的，我添加了一个技巧，让阅读器在使用后做好准备。 - HTH ;)

Answer 2

在ShA.t's answer 的启发下，我能够使标题行和列准确地读取它们在 excel 文档中的开始位置。只要您知道行的开始位置，您只需要过滤空列。这是一个示例代码：

public class TrimmedTableSample 
{
    #region Properties
    int HeaderRowIndex { get; set; }
    #endregion

    #region Methods
    public void Read(string documentPath)
    {
        using (var stream = File.Open(documentPath, FileMode.Open, FileAccess.Read))
        using (var reader = ExcelReaderFactory.CreateReader(stream))
        {
            var dataSet = reader.AsDataSet(new ExcelDataSetConfiguration()
            {
                UseColumnDataType = true,
                ConfigureDataTable = (tableReader) => new ExcelDataTableConfiguration()
                {
                    EmptyColumnNamePrefix = "Column ",
                    UseHeaderRow = true,
                    ReadHeaderRow = (reader) =>
                    {
                        bool empty = true;
                        HeaderRowIndex = 0;

                        while (empty)
                        {
                            for (var i = 0; i < reader.FieldCount && empty; i++)
                                empty = string.IsNullOrWhiteSpace(reader.GetString(i));

                            if (empty)
                            {
                                empty = reader.Read(); // Only continue if more content is available
                                HeaderRowIndex++; // Keep track of the first row position.
                            }
                        }
                    },
                    FilterColumn = (reader, index) =>
                    {
                        bool empty = false;
                        string sheet = reader.Name;

                        // Start reading the table from the beginning
                        reader.Reset();

                        // EDIT: Head over the our current excel sheet
                        while (reader.Name != sheet)
                        if (!reader.NextResult())
                            break;


                        // Head to the first row with content
                        int rowIndex = 0;
                        while (rowIndex < HeaderRowIndex)
                        {
                            reader.Read();
                            rowIndex++;
                        }

                        while (reader.Read())
                        {
                            // Decide if the current column is empty
                            if (reader[index] == null || string.IsNullOrEmpty(reader[index].ToString()))
                                continue;

                            empty = true;
                            break;
                        }

                        // Start over again (This allows the reader to automatically read the rest of the content itself)
                        reader.Reset();

                        // EDIT: Head over the our current excel sheet
                        while (reader.Name != sheet)
                        if (!reader.NextResult())
                            break;

                        reader.Read();

                        // Head over to the first row with content
                        rowIndex = 0;
                        while (rowIndex < HeaderRowIndex)
                        {
                            reader.Read();
                            rowIndex++;
                        }

                        // Return info on whether this column should be ignored or not.
                        return empty;
                    }
                }
            });  
        }
    }
    #endregion
}

祝你好运！

Answer 3

我使用这个通过调用 DataRow.Delete() 方法来工作的解决方案：

                    foreach (var row in rows)
                    {
                        var emptyColumnsCount = 0;
                        for (var i = 0; i < columns.Count; i++)
                        {
                            if (!row.IsNull(columns[i]))
                            {
                               // Do some logic to read row.
                            }
                            else
                            {
                                emptColumnsCount++;
                            }
                        }
                        if (emptyColumnsCount == columns.Count)
                            row.Delete();
                        else
                           // Do some logic to use row
                    }