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How to perform Excel formula calculation in web service using Essential XlsIO?

Platform: ASP.NET Web Forms (Classic) |
Control: XlsIO



This topic gives an overview of how to create a web service that loads an excel template and displays calculated values using Essential XlsIO.




The following steps are to be followed to achieve this.


  1. Create a Web Service project
  1. Initialize XlsIO and perform excel formula calculations


  1. Create a Web Application project
  1. Refer the Web Service link and initialize the service in the Web Application
  2. Update calculated values in the web application through web service


Create a Web Service


  1. Create an empty web application and add Web Service (ASMX) item into the project.


  1. Refer the below dlls
  1. Syncfusion.Core.dll
  2. Syncfusion.Compression.Base.dll
  3. Syncfusion.XlsIO.Web.dll


  1. Use the namespace Syncfusion.XlsIO in web service class (WebService1).



using Syncfusion.XlsIO;


  1. Initialize ExcelEngine object and open the excel workbook template (FederalTaxCalculatorTemplate.xlsx) in web service class (WebService1).



//Represents Excel application
static ExcelEngine excelEngine;
//Represents Excel workbook
static IWorkbook workbook;
static WebService1()
    //Step 1 : Instantiate the spreadsheet creation engine.
    excelEngine = new ExcelEngine();
    //Step 2 : Instantiate the excel application object.
    IApplication application = excelEngine.Excel;
    string filePath = HttpContext.Current.Server.MapPath("/App_Data/FederalTaxCalculatorTemplate.xlsx");
    // An existing workbook is opened.
    //[Equivalent to opening an existing workbook in MS Excel]
    workbook = excelEngine.Excel.Workbooks.Open(filePath);


  1. Add SetValues and GetValues methods in the class (WebService1). The SetValues method sets the values into worksheet. The GetValues method returns XlsIO calculated values from worksheet.



/// <summary>
/// Sets the provided values to the excel workbook
/// </summary>
/// <param name="inputValues">Array of input values to fill the workbook</param>
public void SetValues(double[] inputValues)
    List<string> calculatedList = new List<string>();
    lock (workbook)
        IWorksheet sheet = workbook.Worksheets[0];
        //Filing Status
        sheet.ComboBoxes[0].SelectedIndex = Convert.ToInt16(inputValues[0]);
        //Over Age 65
        sheet["F8"].Number = Convert.ToDouble(inputValues[1]);
        //Personal Excemptions
        sheet["F9"].Number = Convert.ToDouble(inputValues[2]);
        //Dependant Children
        sheet["F10"].Number = Convert.ToDouble(inputValues[3]);
        //Gross Annual Income
        sheet["F12"].Number = Convert.ToDouble(inputValues[4]);
        sheet["F13"].Number = Convert.ToDouble(inputValues[5]);
        //Itemized Deductions
        sheet["F15"].Number = Convert.ToDouble(inputValues[6]);  
/// <summary>
/// Returns workbook cell values
/// </summary>
/// <returns>String collection to display the values in UI</returns>
public List<string> GetValues()
    List<string> valuesList = new List<string>();
    lock (workbook)
        IWorksheet sheet = workbook.Worksheets[0];
        int selectedIndex = 0;
        if (sheet.ComboBoxes.Count > 0)
            selectedIndex = sheet.ComboBoxes[0].SelectedIndex - 1;
        //0 Filing Status
        //1 Over Age 65
        //2 Personal Excemptions
        //3 Dependant Children
        //4 Gross Annual Income
        //5 Adjustments
        //6 Adjusted Gross Income
        //7 Itemized Deductions
        double grossIncome = Convert.ToDouble(sheet["F14"].CalculatedValue);
        if (grossIncome > 0)
            //8 Standard Deductions
            //9 Excemption Dollars
            //8 Standard Deductions
            //9 Excemption Dollars
        //10 Taxable Income
        //11 Tax Estimate
    return valuesList;


  1. Now, right-click at WebService1.asmx file from Solution Explorer and select View in Browser menu.



Create a Web Application


  1. Create an empty web application and add a Web Form item named default.aspx into the project.


  1. The scenario used here is to calculate Federal Tax Estimation. So, the web page must be designed accordingly. The following screen-shot shows the UI part of the application.


UI screen before calculation using XlsIO

Figure 1 – UI Screen Before Calculation


  1.  Here, the input fields are:

  1. Tax Filing Status
  2. No. of filers over age 65
  3. No. of personal exemptions
  4. No. of dependent children
  5. Gross annual income
  6. Adjustments
  7. Itemized deduction


The rest of the fields are used to display calculated values from excel workbook.

  1. Now, right-click WebApplication1 project from Solution Explorer and click Add->Service Reference->Advanced->Add Web Reference. Paste the web service link copied earlier in the URL field and click Add Reference button.


  1. Following namespace must be used in _default class to initialize web service and access its public methods.



using WebApplication1.localhost;


  1. Initialize the class WebService1 in the _default class.



//Initializes web service
WebService1 service = new WebService1();


  1. Get calculated values from worksheet to display in its respective UI fields. The following code snippet can be used to achieve this.



/// <summary>
/// Fills UI controls with the values retrieved from Excel workbook
/// </summary>
private void FillControlsWithValues()
    string[] result = service.GetValues();
    DpnFilingStatus.SelectedIndex = Convert.ToUInt16(result[0]);
    txtAbove65.Text = result[1];
    txtPersonalExemp.Text = result[2];
    txtDependChild.Text = result[3];
    txtGrossIncome.Text = result[4];
    txtAdjustments.Text = result[5];
    txtAdjustedGrossIncome.Text = result[6];
    txtItemizedDeductions.Text = result[7];
    txtStandardDeductions.Text = result[8];
    txtExempDollars.Text = result[9];
    txtTaxableIncome.Text = result[10];
    txtIncomeTax.Text = result[11];


  1. Submit button sets the input values to the worksheet and returns its calculated values. The following code snippet illustrates that.



/// <summary>
/// Submits the input value into the workbook and 
/// displays the calculated values from the workbook
/// </summary>
/// <param name="sender">button object</param>
/// <param name="e">event argument</param>
protected void btnSubmit_Click(object sender, EventArgs e)
    double[] inputValues = new double[7];
    inputValues.SetValue(Convert.ToDouble(DpnFilingStatus.SelectedIndex + 1), 0);
    inputValues.SetValue(Convert.ToDouble(txtAbove65.Text), 1);
    inputValues.SetValue(Convert.ToDouble(txtPersonalExemp.Text), 2);
    inputValues.SetValue(Convert.ToDouble(txtDependChild.Text), 3);
    inputValues.SetValue(Convert.ToDouble(txtGrossIncome.Text), 4);
    inputValues.SetValue(Convert.ToDouble(txtAdjustments.Text), 5);
    inputValues.SetValue(Convert.ToDouble(txtItemizedDeductions.Text), 6);
    //Enter the input values in to the assigned cells
    //Fills UI controls with the values retrieved from Excel workbook


  1. The following screen-shot shows the output of the sample. For the given Gross Income 75000, the tax estimation is calculated by XlsIO and the calculated values are displayed in its respective fields as shown.

UI screen after calculation using XlsIO

Figure 2 – UI Screen After Calculation




The tax calculation is just to illustrate the calculation at API levels using Essential XlsIO and not exactly the scale of federal tax estimation.



The above sample can be downloaded here.

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