Description

The binding element provides a mechanism in Helium with which to bind values submitted from input widgets to unit variables of a base type or attributes of object instance unit variables. It also provides a way to bind functions to widgets in order to use the values returned from these functions in the widgets.

Example

Binding directly to a unit variable

<datefield label="select.date_of_stocktake">
    <binding variable="selectedDateOfStocktake"/>
</datefield>

date selectedDateOfStocktake;

void init() {
    selectedDateOfStocktake = Mez:now();
}

Binding to a unit variable attribute

View XML

<info label="info.first_name">
    <binding variable="farmer">
        <attribute name="firstName"/>
    </binding>
</info>

Backing unit

Farmer farmer;

void init() {
    Farmer = Farmer:new();
    .
    .
}

Binding to a function

View XML

<info label="info.email_address">
    <binding function="getSystemAdminEmailAddress"/>
</info>

Backing unit

SystemAdmin currentSystemAdminUser;

void init() {
    currentSystemAdminUser = SystemAdmin:user();
    .
    .
}
string getSystemAdminEmailAddress() {
    return currentSystemAdminUser.emailAddress;
}

Additional Mentions and References

Used in multiple lessons in the Helium Tutorial with first mention in Lesson 1: A Basic Helium App
Multiple examples in the Helium Quick Reference

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