Question

我正在尝试从一个excel文件中的多个工作表中读取数据，在此过程中我遇到了一个问题或另一个问题。我现在遇到的当前问题是执行测试时遇到的“对象引用未设置为对象实例”。

我尝试使用OLEDB连接，但无济于事。我仍然是编码方面的新手，将不胜感激。

//的单例对象公共类ExcelDataContext { //创建一个ExcelDataContext对象私有静态只读ExcelDataContext实例=新的ExcelDataContext（）;

    // no instantiated available
    private static DataTable GetExcelDataContext(string filename)
    {
        FileStream stream = File.Open(filename, FileMode.Open, FileAccess.Read);
        IExcelDataReader excelReader = ExcelReaderFactory.CreateOpenXmlReader(stream);

        DataSet result = excelReader.AsDataSet(new ExcelDataSetConfiguration()
        {
            ConfigureDataTable = (_) => new ExcelDataTableConfiguration()
            {
                UseHeaderRow = true
            }
        });


        foreach (DataTable sheet in result.Tables)
        {
            DataTableCollection tableCollection = result.Tables;
            if (sheet.Equals(tableCollection["loginData"]))
            {
                DataTable loginDataTable = GetInstance().Sheets["loginData"];
                return loginDataTable;

            }
            if (sheet.Equals(tableCollection["homeData"]))
            {
                DataTable homeDataTable = GetInstance().Sheets["homeData"];

                return homeDataTable;
            }
            excelReader.Close();
        }
        return new DataTable();
    }

    // accessing to ExcelDataContext singleton
    public static ExcelDataContext GetInstance()
    {
        return Instance;
    }

    // the dataset of Excel
    public DataTableCollection Sheets => null;


    public class DataCollection
    {
        public int RowNumber { get; set; }
        public string ColName { get; set; }
        public string ColValue { get; set; }
    }

    static readonly List<DataCollection> DataCollections = new List<DataCollection>();

    public static void PopulateInCollection(string filename)
    {
        DataTable dataTable = GetExcelDataContext(filename);
        for (int row = 1; row <= dataTable.Rows.Count; row++) //row =1 because we are  not using header name
        {
            for (int col = 0; col < dataTable.Columns.Count; col++)
            {
                DataCollection collection = new DataCollection()
                {
                    RowNumber = row,
                    ColName = dataTable.Columns[col].ColumnName, //return column name
                    ColValue = dataTable.Rows[row - 1][col].ToString()
                };
                DataCollections.Add(collection);
            }
        }
    }

    public static string ReadData(int rowNumber, string columnName)
    {
        try
        {
            string data =
            (from colData in DataCollections
                where colData.ColName == columnName && colData.RowNumber == rowNumber
                select colData.ColValue).SingleOrDefault();

            return data;
        }
        catch (Exception)
        {
            return null;
        }
    }


}

我希望能够从每个Excel工作表中获取数据。

Answer 1

问题是：没有实例化的对象。尝试找出哪个类不是通过调试实例化的。

如何修复“对象引用未设置为对象实例”

1 个答案: