Manipulating Objects from JavaScript

Creating objects

A new object can be created using the syntax DB.object_type.create().

As an example, suppose we have an object type "person" with an attribute "name".

We would define a variable for the object, and initialise it as follows:

View XML:

<view ...>
    <var name="visitor" type="person" />
</view>

... and View JavaScript:

function init() {
    view.visitor = DB.person.create();
    view.visitor.name = "John";
}

All objects that are defined as variables in a view are saved automatically whenever a view is dismissed, but not when the user presses the back button. However, when defining an object only in JavaScript (and not in the view), you need to save the object manually:

var visitor = DB.person.create();
visitor.name = "John";
visitor.save();

Setting dates and times

Both date and datetime attributes are represented as the JavaScript Date type. To set a date or datetime to the current date/time, use new Date(). To set it to a specific date, use new Date(year, month, day). For more details, see this article at Mozilla.

Examples:

view.registration_date = new Date();
view.current_time = new Date();
view.birthdate = new Date(1972, 3, 19);

Deleting objects

An object can be deleted using its destroy() function.

As an example, suppose we have an object type "person":

View XML:

<view ...>
    <var name="visitor" type="person" />
</view>

... and View JavaScript:

view.person.destroy();

Setting relationships

Unlike attributes, a relationship is set using a setter function.

As an example, suppose that in our Data Model every person is part of a household:

<schema>
    <object name="person">
        <attribute name="name" type="string" />

        <belongs_to type="household" />

        <display format="{name}" />
    </object>

    <object name="household">
        <attribute name="address" type="string" />

        <has_many type="person" name="members" />

        <display format="{address}" />
    </object>
</schema>

In our view we define our household and person:

<view ...>
    <var name="member" type="person" />
    <var name="household" type="household" />
</view>

... and initialise them in JavaScript:

function init() {
    view.household = DB.household.create();
    view.member = DB.person.create();
    view.member.household(view.household);
}

As you can see, we set the "household" relationship on the "member" by calling the household() function and passing the related "household" object as an argument.

As a more typical example, the household will be created in another view and passed as a parameter:

<view ...>
    <param name="household" type="household" />
    <var name="member" type="person" />
</view>

... and the JavaScript:

function init() {
    view.member = DB.person.create();
    view.member.household(view.household);
}

Getting relationships

Getting a related object works that a particular object belongs to is done by calling a getter function, as seen below:

view.member.household();