JJMasterData.NCalc

Configuration

Add the following method to MasterDataServiceBuilder:

builder.AddJJMasterDataWeb().WithNCalcExpressionProvider();

Options

• Check NCalcExpressionProviderOptions

Usage

Expressions are pre-parsed just like the Value and DataTable providers. Using {}.

NCalc support more operators and alias than DataTable.Compute, like "if" statements or ternary operators.

if('{MyColumn}',1,0)

'{MyColumn}' ? 'true result' : 'false result'

'{MyColumn}' != 1 AND {'MyColumn'} <> 1

You can also create your own custom functions.

Check NCalc wiki for more information.

Differences from DataTable.Compute

• NCalc is a mathematical expressions evaluator not a SQL-like syntax parser
• Better performance is expected

Executing C# code at your expressions

You can execute C# code using the following example;

Program.cs:

builder.Services.AddJJMasterDataWeb()
.WithNCalcExpressionProvider(
    new NCalcExpressionProviderOptions
    {
        ReplaceDefaultExpressionProvider = true,
        AdditionalFunctions = [
            (name, args) =>
            {
                args.Result = name switch
                {
                    "now" => DateTime.Now,
                    "myawesomefunction" => MyCustomClass.Execute(args.Parameters[0], args.Parameters[1]),
                     _ => args.Result
                };
            }
        ]
    }
);

Warning

NCalc sends function names in lowercase.

At your expression:

exp: myAwesomeFunction('{StringValue}',{IntValue})