<binding/>

1 Description
2 Example
- 2.1 Binding directly to a unit variable
- 2.2 Binding to a unit variable attribute
  - 2.2.1 View XML
  - 2.2.2 Backing unit
- 2.3 Binding to a function
  - 2.3.1 View XML
  - 2.3.2 Backing unit
3 Additional Mentions and References

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