读取非常大的Excel文件

Question

I am using this article to read a very large excel file, using SAX approach.

https://msdn.microsoft.com/en-us/library/office/gg575571.aspx

Can't store values in a DataTable or memory due to a client machine not having enough memory. Trying to read and right away store values into a database:

// The SAX approach.

static void ReadExcelFileSAX(string fileName)
{
        using (SpreadsheetDocument spreadsheetDocument = SpreadsheetDocument.Open(fileName, false))
    {

        WorkbookPart workbookPart = spreadsheetDocument.WorkbookPart;
        WorksheetPart worksheetPart = workbookPart.WorksheetParts.First();

        OpenXmlReader reader = OpenXmlReader.Create(worksheetPart);
        string text;
        while (reader.Read())
        {
            if (reader.ElementType == typeof(CellValue))
            {
                text = reader.GetText();
                Console.Write(text + " ");
            }
        }
        Console.WriteLine();
        Console.ReadKey();
    }
}

For example when I read this excel file:

Test 1
22
345345
345345435
2333
333333
4444
4444444
324324
99999

I get this output:

Blank
22
Blank
345345
Blank 
etc

I have no idea where the blanks are coming from. Tried to put the if statement in there testing for blanks then I miss the last value 99999.

That reader seems so limited. Would really appreciate a suggestion, I mean anything!

Answer 1

The OpenXmlReader treats the start and end elements as independant items. These can be differentiated by checking the IsStartElement and IsEndElement properties.

Your blank values are due to the end elements where GetText returns the empty string.

You have 2 options to fix it. Firstly you could check for IsStartElement in your loop:

while (reader.Read())
{
    if (reader.ElementType == typeof(CellValue)
        && reader.IsStartElement)
    {
        text = reader.GetText();
        Console.WriteLine(text + " ");
    }
}

Alternatively you can use the LoadCurrentElement method to load the whole element, consuming both the start and end you were getting before:

while (reader.Read())
{
    if (reader.ElementType == typeof(CellValue))
    {
        CellValue cellVal = (CellValue)reader.LoadCurrentElement();
        Console.WriteLine(cellVal.Text);
    }
}