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Microsoft.Interop.Excel can't read cell value

I wrote a small method that will give me the headers of a table in excel:
private List<string> GetCurrentHeaders(int headerRow, Excel.Worksheet ws)
{
//List where specific values get saved if they exist
List<string> headers = new List<string>();
//List of all the values that need to exist as headers
var headerlist = columnName.GetAllValues();
for (int i = 0; i < headerlist.Count; i++)
{
//GetData() is a Method that outputs the Data from a cell.
//headerRow is defining one row under the row I actually need, therefore -1 )
string header = GetData(i + 1, headerRow - 1, ws);
if (headerlist.Contains(header) && !headers.Contains(header))
{
headers.Add(header);
}
}
return headers;
}
Now I got an Excel-table, where the first value I need is in cell A11 (or Row 11, Column 1).
When I set a breakpoint after string header = GetData(i + 1, headerRow - 1, ws);, where i+1 = 1 and headerRow - 1 = 11, I can see that the value he read is empty, which is not the case.
The GetData-Method just does one simple thing:
public string GetData(int row, int col, Excel.Worksheet ws)
{
string val = "";
val = Convert.ToString(ws.Cells[row, col].Value) != null
? ws.Cells[row, col].Value.ToString() : "";
val = val.Replace("\n", " ");
return val;
}
I don't get why this can't get me the value I need, while it works on every other excel table too. The excel itself is no different from the others. It's file extension is .xls, the data is in the same layout as in the other tables, etc

There are a few steps to getting this right. You need to know the dimensions of your table to know where the headers are. Your method hast two ways of knowing this: 1) passing the table Range to the method, or 2) giving the coordinates of a cell within the table (usually the top-left cell) and trusting the CurrentRegion property to do the job for you. The most reliable way would be the first as you will be explicitly telling the method where to look, but it'll require the consumer to figure out the address which isn't always straightforward. The CurrentRegion approach works fine too but note that if you have an empty column within your table range, it will only address until that empty column. Having said all that, you could have the following:
List<string> GetHeaders(Worksheet worksheet, int row, int column)
{
Range currentRegion = worksheet.Cells[row, column].CurrentRegion;
Range headersRow = currentRegion.Rows[1];
var headers = headersRow
.Cast<Range>() // We cast so we can use LINQ
.Select(c => c.Text is DBNull ? null : c.Text as string) //The null value of c.Text is not null but DBNull
.ToList();
return headers;
}
Then you can simply test if you're missing headers. The following code assumes the ActiveCell is a cell within the table Range, but you can change that easily to address a specific cell.
List<string> GetMissingHeaders(List<string> expectedHeaders)
{
var worksheet = App.ActiveSheet; //App is your Excel application
Range activeCell = worksheet.ActiveCell;
var headers = GetHeaders(worksheet, activeCell.Row, activeCell.Column);
return expectedHeaders.Where(h => headers.Any(i => i == h) == false).ToList();
}

How to get excel column with the column index in NPOI C#

I want to set the cell formula for columns k-P by using a loop and in c# i can only loop with integers, how do you actually get the column(E.G K,L,M,N,O,P) with the index? for looping through rows its pretty easy because they are just numbers but for columns excel uses letters.
I cant think of anything other than defining my own List for letters k-P in c#

You can use CellReference, if you already have the cell object.
var temp = new CellReference(cell);
var reference = temp.FormatAsString();
Hope this works for you!

Allso you can get it directly from ICell object:
var adress = cell.Address.FormatAsString();
Ore if you need column name only add method like this:
public static string GetColumnName(this ICell cell)
{
return Regex.Match(cell.Address.FormatAsString(), #"[A-Z]+").Value;
}
And then just call it like:
var colName = cell.GetColumnName();

C# LinqToExcel GetColumnName nth row [duplicate]

I am using the library LinqToExcel to read excel files in my mvc4 project. My problem is when I try to read the headers at row 4... How I can do this?
In project, exists a function that returns all the column names, but I suppose that the columns need to be at row 0.
// Summary:
// Returns a list of columns names that a worksheet contains
//
// Parameters:
// worksheetName:
// Worksheet name to get the list of column names from
public IEnumerable<string> GetColumnNames(string worksheetName);
Thanks.

Unfortunately the GetColumnNames() method only works when the header row is on row 1.
However, it should be possible to get the column names by using the WorksheetRangeNoHeader() method.
It would look something like this
var excel = new ExcelQueryFactory("excelFileName");
// Only select the header row
var headerRow = from c in excel.WorksheetRangeNoHeader("A4", "Z4")
select c;
var columnNames = new List<string>();
foreach (var headerCell in headerRow)
columnNames.Add(headerCell.ToString());

An FYI for future googlers:
It appears that GetColumnNames() has changed since the above answer was accepted.
There is now an overload in which you can define the range of the header row as a string:
// This will return a List<string>
var colNames = ExcelFile
.GetColumnNames(SheetName, "A9:AF9")
.ToList();

How can I determine how many rows a PivotTable generates (Aspose Cells)?

I need to conditionally colorize ranges in a PivotTable. I tried to do it this way:
private void ColorizeContractItemBlocks(List<string> contractItemDescs)
{
int FIRST_DESCRIPTION_ROW = 7;
int DESCRIPTION_COL = 1;
int ROWS_BETWEEN_DESCRIPTIONS = 4;
int rowsUsed = pivotTableSheet.Cells.Rows.Count;
int currentRowBeingExamined = FIRST_DESCRIPTION_ROW;
// Loop through PivotTable data, colorizing contract items
while (currentRowBeingExamined < rowsUsed)
{
Cell descriptionCell = pivotTableSheet.Cells[currentRowBeingExamined, DESCRIPTION_COL];
String desc = descriptionCell.Value.ToString();
if (contractItemDescs.Contains(desc))
{
// args are firstRow, firstColumn, totalRows, totalColumns
Range rangeToColorize = pivotTableSheet.Cells.CreateRange(
currentRowBeingExamined, 0,
ROWS_BETWEEN_DESCRIPTIONS, _grandTotalsColumnPivotTable + 1);
Style style = workBook.Styles[workBook.Styles.Add()];
style.BackgroundColor = CONTRACT_ITEM_COLOR;
StyleFlag styleFlag = new StyleFlag();
styleFlag.All = true;
rangeToColorize.ApplyStyle(style, styleFlag);
}
currentRowBeingExamined = currentRowBeingExamined + ROWS_BETWEEN_DESCRIPTIONS;
}
}
...but it doesn't work, because rowsUsed does not take into consideration the rows on the PivotTable on the pivotTableSheet, and so my while loop is never entered.
How can I determine how many rows the PivotTable takes up on the sheet, so that I can loop through the PivotTable?
Or, am I approaching this the wrong way? Is there a different standard way of manipulating the styles/formatting of a PivotTable after it has been generated?

#B. Clay Shannon, You may consider using any of the following APIs for your requirement. I have added comments to the code for your reference.
var book = new Workbook(dir + "sample.xlsx");
var sheet = book.Worksheets[0];
var pivot = sheet.PivotTables[0];
// DataBodyRange returns CellArea that represents range between the header row & insert row
var dataBodyRange = pivot.DataBodyRange;
Console.WriteLine(dataBodyRange);
// TableRange1 returns complete Pivot Table area except page fields
var tableRange1 = pivot.TableRange1;
Console.WriteLine(tableRange1);
// TableRange2 returns complete Pivot Table area including page fields
var tableRange2 = pivot.TableRange2;
Console.WriteLine(tableRange2);
// ColumnRange returns range that represents the column area of the Pivot Table
var columnRange = pivot.ColumnRange;
Console.WriteLine(columnRange);
// RowRange returns range that represents the row area of the Pivot Table
var rowRange = pivot.RowRange;
Console.WriteLine(rowRange);
In case you still face any difficulty, please share your sample spreadsheet along with desired results (that you may create manually in Excel application) in a thread at Aspose.Cells support forum for thorough investigation.
Note: I am working as Developer Evangelist at Aspose.

The RowRange property of the pivot table should take you row by row through every element in the table:
Excel.Worksheet ws = wb.Sheets["Sheet1"];
Excel.PivotTable pt = ws.PivotTables("PivotTable1");
Excel.Range cell;
foreach (Excel.Range row in pt.RowRange)
{
cell = ws.Cells[row.Row, 5]; // for example, whatever is in column E
// do your formatting here
}
There are other ranges available -- for example, I typically only care about:
pt.DataBodyRange
Which is every cell within the actual pivot table (whatever is being aggregated).

How to find duplicate values in Excel cells between multiple sheets programmatically

For example, I have a sheet called EmployeeSheet, which is just a single column of every employee's name first and last in a company. And let's assume this list is perfectly formatted and has no duplicates so every cell is unique in this sheet.
Now I have a sheet for each department in the company, such as FinanceSheet, ITSheet, and SalesSheet. Each sheet has in it somewhere (as in each sheet doesn't have the same layout) a list of employees in each department. However any 1 employee name should only appear once between all of the department sheets (this excludes the EmployeeSheet).
Here's the solution I can think of but not figure out how to implement, would be to make a multidimensional array (Learned a small bit about them in school, vaguely remember how to use though).
Pseudocode something like:
arrEmployees = {"Tom Hanks", "Burt Reynolds", "Your Mom"}
arrFinance = {"Tom Hanks"}
arrIT = {"Burt Reynolds"}
arrSales = {"Your Mom"}
arrSheets = {arrEmployees, arrFinance, arrIT, arrSales}
While I've been able to get single cell values and ranges as strings by using
Sheets shts = app.Worksheets;
Worksheet ws = (Worksheet)sheets.get_Item("EmployeeSheet");
Excel.Range empRange = (Excel.Range)worksheet.get_range("B2");
string empVal = empRange.Value2.ToString();
But with that process to get a single cell value to a string, I don't know how I would put that into an element of my array, let alone a range of values.
I'm sure my method is not the most efficient, and it might not even be possible, but that's why I'm here for help, so any tips are appreciated.
EDIT: This is the solution that ended up working for me. Thanks to Ian Edwards solution.
Dictionary<string, List<Point>> fields = new Dictionary<string, List<Point>>();
fields["Finance"] = new List<Point>() { new Point(2,20)};
fields["Sales"] = new List<Point>();
for (int row = 5; row <= 185; row += 20) {fields["Sales"].Add(new Point(2,row));}
List<string> names = new List<string>();
List<string> duplicates = new List<string>();
foreach (KeyValuePair<string, List<Point>> kp in fields)
{
Excel.Worksheet xlSheet = (Excel.Worksheet)workbook.Worksheets[kp.Key];
foreach (Point p in kp.Value)
{
if ((xlSheet.Cells[p.Y, p.X] as Excel.Range.Value != null)
{
string cellVal = ((xlSheet.Cells[p.Y,p.X] as Excel.Range).Value).ToString();
if (!names.Contains(cellVal))
{ names.Add(cellVal)) }
else { duplicates.Add(cellVal); } } } }

Here's a little example I knocked together - the comments should explain what's going on line by line.
You can declare the name of the worksheets you want to check for names, as well as where to start looking for names in the 'worksheets' dictionary.
I assume you don't know how many names are in each list - it will keep going down each list until it encounters a blank cell.
// Load the Excel app
Microsoft.Office.Interop.Excel.Application xlApp = new Microsoft.Office.Interop.Excel.Application();
// Open the workbook
var xlWorkbook = xlApp.Workbooks.Open("XLTEST.xlsx");
// Delcare the sheets and locations to look for names
Dictionary<string, Tuple<int, int>> worksheets = new Dictionary<string, Tuple<int, int>>()
{
// Declare the name of the sheets to look in and the 1 base X,Y index of where to start looking for names on each sheet (i.e. 1,1, = A1)
{ "Sheet1", new Tuple<int, int>(1, 1) },
{ "Sheet2", new Tuple<int, int>(2, 3) },
{ "Sheet3", new Tuple<int, int>(4, 5) },
{ "Sheet4", new Tuple<int, int>(2, 3) },
};
// List to keep track of all names in all sheets
List<string> names = new List<string>();
// Iterate over every sheet we need to look at
foreach(var worksheet in worksheets)
{
string workSheetName = worksheet.Key;
// Get this excel worksheet object
var xlWorksheet = (Microsoft.Office.Interop.Excel.Worksheet)xlWorkbook.Worksheets[workSheetName];
// Get the 1 based X,Y cell index
int row = worksheet.Value.Item1;
int column = worksheet.Value.Item2;
// Get the string contained in this cell
string name = (string)(xlWorksheet.Cells[row, column] as Microsoft.Office.Interop.Excel.Range).Value;
// name is null when the cell is empty - stop looking in this sheet and move on to the next one
while(name != null)
{
// Add the current name to the list
names.Add(name);
// Get the next name in the cell below this one
name = (string)(xlWorksheet.Cells[++row, column] as Microsoft.Office.Interop.Excel.Range).Value;
}
}
// Compare the number of names to the number of unique names
if (names.Count() != names.Distinct().Count())
{
// You have duplicate names!
}

You can use .Range to define multiple cells (ie, .Range["A1", "F500"])
https://msdn.microsoft.com/en-us/library/microsoft.office.tools.excel.worksheet.range.aspx
You can then use .get_Value to get the contents/values of all cells in that Range. According to dotnetperls.com get_Value() is much faster than get_Range() (see 'Performance' section). Using the combo of multiple ranges + get_value will definitely perform better of lots of single range calls using get_range.
https://msdn.microsoft.com/en-us/library/microsoft.office.tools.excel.namedrange.get_value(v=vs.120).aspx
I store them in the an Object Array.
(object[,])yourexcelRange.get_Value(Excel.XlRangeValueDataType.xlRangeValueDefault);
From there you can write your own comparison method to compare multiple arrays. One quirk is that doing this returns a 1-indexed array, instead of a standard 0-based index.