Table of Contents

Creating a minus operator

In this tutorial, you will learn how to create a custom operator that subtracts two values and adds the result to a table. You could, for example, use this operator to calculate the profit for each project in this table:

Project (String) Customer (Int) Sales (Double) Cost (Double)
Project 1 Customer A €1000 €750.0
Project 2 Customer B €2000 €250.0
Project 3 Customer A €1500 €500.0

The result will look like this:

Project (String) Customer (Int) Sales (Double) Cost (Double) Profit (Double)
Project 1 Customer A €1000 €750.0 €250.0
Project 2 Customer B €2000 €250.0 €1750.0
Project 3 Customer A €1500 €500.0 €1000.0

Estimated duration: 20 minutes.

Tip

See also: Configuring a custom operator for a query

Note

This tutorial uses DataMiner version 10.3.2.

Prerequisites

Overview

Step 1: Create a basic implementation

Create a new class that implements the IGQIColumnOperator and the IGQIRowOperator interfaces.

  • To create a new column called "Profit" to store your results, you need the IGQIColumnOperator interface.

    This interface features a single function, HandleColumns, which provides the implementation with information about the available columns and makes it possible to create, rename, and add columns.

  • To calculate the profit based on the Sales and Cost values and update the Profit column cells with the calculated result, you need the IGQIRowOperator interface.

    This interface features a single function, HandleRow, which allows the implementation to read and update cells within a row.

Tip

For an overview of all predefined interfaces that can be implemented by a custom operator, see Building blocks

Above the class, add the GQIMetaData attribute to configure the name of the data source as displayed in the Dashboards app or Low-Code Apps.

Note

All types needed to create a user-definable operator can be found within the Skyline.DataMiner.Analytics.GenericInterface namespace.

[GQIMetaData(Name = "Minus operator")]
public class MyCustomOperator : IGQIColumnOperator, IGQIRowOperator
{
    private GQIDoubleColumn _profitColumn = new GQIDoubleColumn("Profit");

    public void HandleColumns(GQIEditableHeader header)
    {
        header.AddColumns(_profitColumn);
    }

    public void HandleRow(GQIEditableRow row)
    {
        var sales = row.GetValue<double>("Sales");
        var cost = row.GetValue<double>("Cost");
        var profit = sales - cost;

        row.SetValue(_profitColumn, profit, $"€{profit}");
    }
}

Step 2: Make the operator reusable

The solution you have just created is specific to the data. To make the operator more generic and reusable, allow users to select the columns used for subtraction in the query builder and choose a custom name for the newly generated column. This means you will no longer hardcode the column name ("Profit") or the columns that contain the Sales and Cost values.

To allow users to interact with the custom operator, implement the IGQIInputArguments interface.

The IGQIInputArguments interface features two functions, GetInputArguments and OnArgumentsProcessed.

  • The GetInputArguments function allows the GQI to know the input required by the user. In this case, the user needs to choose a first column, a second column, and a column name.

    The GQIColumnDropdownArgument argument allows users to select columns by displaying a dropdown list with all applicable columns. The Types property ensures only columns of type Double are available for selection.

    private GQIColumnDropdownArgument _firstColumnArg = new GQIColumnDropdownArgument("First column") { IsRequired = true, Types = new GQIColumnType[] { GQIColumnType.Double } };
private GQIColumnDropdownArgument _secondColumnArg = new GQIColumnDropdownArgument("Second column") { IsRequired = true, Types = new GQIColumnType[] { GQIColumnType.Double } };
private GQIStringArgument _nameArg = new GQIStringArgument("Column name") { IsRequired = true };

public GQIArgument[] GetInputArguments()
{
    return new GQIArgument[] { _firstColumnArg, _secondColumnArg, _nameArg };
}

  • The OnArgumentsProcessed function, with the OnArgumentsProcessedInputArgs argument, allows the value to be processed.

    private GQIColumn _firstColumn;
private GQIColumn _secondColumn;
private GQIDoubleColumn _newColumn;

public OnArgumentsProcessedOutputArgs OnArgumentsProcessed(OnArgumentsProcessedInputArgs args)
{
    _firstColumn = args.GetArgumentValue(_firstColumnArg);
    _secondColumn = args.GetArgumentValue(_secondColumnArg);
    _newColumn = new GQIDoubleColumn(args.GetArgumentValue(_nameArg));

    return new OnArgumentsProcessedOutputArgs();
}

Final result

In the end, the code of your minus operator should look like this:

using Skyline.DataMiner.Analytics.GenericInterface;

[GQIMetaData(Name = "Minus operator")]
public class MyCustomOperator : IGQIColumnOperator, IGQIRowOperator, IGQIInputArguments
{
    private GQIColumnDropdownArgument _firstColumnArg = new GQIColumnDropdownArgument("First column") { IsRequired = true, Types = new GQIColumnType[] { GQIColumnType.Double } };
    private GQIColumnDropdownArgument _secondColumnArg = new GQIColumnDropdownArgument("Second column") { IsRequired = true, Types = new GQIColumnType[] { GQIColumnType.Double } };
    private GQIStringArgument _nameArg = new GQIStringArgument("Column name") { IsRequired = true };

    private GQIColumn _firstColumn;
    private GQIColumn _secondColumn;
    private GQIDoubleColumn _newColumn;

    public GQIArgument[] GetInputArguments()
    {
        return new GQIArgument[] { _firstColumnArg, _secondColumnArg, _nameArg };
    }

    public OnArgumentsProcessedOutputArgs OnArgumentsProcessed(OnArgumentsProcessedInputArgs args)
    {
        _firstColumn = args.GetArgumentValue(_firstColumnArg);
        _secondColumn = args.GetArgumentValue(_secondColumnArg);
        _newColumn = new GQIDoubleColumn(args.GetArgumentValue(_nameArg));

        return new OnArgumentsProcessedOutputArgs();
    }

    public void HandleColumns(GQIEditableHeader header)
    {
        header.AddColumns(_newColumn);
    }

    public void HandleRow(GQIEditableRow row)
    {
        var firstValue = row.GetValue<double>(_firstColumn);
        var secondValue = row.GetValue<double>(_secondColumn);
        var result = firstValue - secondValue;

        row.SetValue(_newColumn, result, $"€{result}");
    }
}
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