SMART datagrid v.1 > Classes > DerivedField

DataLudi.DerivedField.expression  property

Expression which returns the value to be saved in field. 

You can directly use the name of common fields as variable in expression, but should not refer other derived field. You can also return the value by callback property instead of this expression. 

You can use the variables listed in the table below in expression besides common field names. 

Defaults to null.

Getter

function expression(): String

Setter

function setExpression(value: String)

    var fields = [];
    var calcedFields = [
        {
            fieldName: "amount",
            dataType: "number",
            expression: "unit_price * quantity"
        },
        ...
    ];
    ds.setFields(fields, calcedFields);

When the field name starts with number, since expression parser will read it as number value, you should use "values" variable. 

    var fields = [];
    var calcedFields = [
        {
            expression: "values['01_unit'] * values['02_unit']"
        },
        ...
    ];

You should not refer other derived field in expression. 

See Also

callback

DataSet.setFields

Expression Overview

Examples

Derived Fields

Row Summary