Actions¶
Components can also trigger methods from the templates by listening to any valid event type. The most common events would be click, input, keydown, keyup, and mouseenter, but MDN has a list of all of the browser event types available.
Events¶
An example action to call the clear_name method on the component.
<!-- clear-name.html -->
<div>
<input unicorn:model="name" type="text" id="text" />
Hello {{ name|title }}
<button unicorn:click="clear_name">Clear Name</button>
</div>
# clear_name.py
from django_unicorn.components import UnicornView
class ClearNameView(UnicornView):
name = "World"
def clear_name(self):
self.name = ""
When the button is clicked, the name property will get set to an empty string. Then, the component will intelligently re-render itself and the text input will update to match the property on the component.
Tip
Instance methods without arguments can be called from the template with or without parenthesis.
Passing arguments¶
Actions can also pass basic Python types to the backend component.
<!-- passing-args.html -->
<div>
<input unicorn:model="name" type="text" id="text" />
Hello {{ name|title }} 👋
<button unicorn:click="set('Bob')">Set as Bob</button>
<button unicorn:click="set()">Set default value of name argument</button>
</div>
# passing_args.py
from django_unicorn.components import UnicornView
class PassingArgsView(UnicornView):
name = "World"
def set(self, name="Universe"):
self.name = name
Argument types¶
Arguments can be most basic Python types, including string, int, float, bool, list, tuple, dictionary, set, datetime, and UUID4.
<!-- argument-types.html -->
<div>
<button unicorn:click="update(99)">Pass int</button>
<button unicorn:click="update(1.234)">Pass float</button>
<button unicorn:click="update(True)">Pass bool</button>
<button unicorn:click="update({'key': 'value'})">Pass dictionary</button>
<button unicorn:click="update([1, 2, 3])">Pass list</button>
<button unicorn:click="update((1, 2, 3))">Pass tuple</button>
<button unicorn:click="update({1, 2, 3})">Pass set</button>
<button unicorn:click="update(2020-09-12T01:01:01)">Pass datetime</button>
<button unicorn:click="update(90144cb9-fc47-476d-b124-d543b0cff091)">
Pass UUID
</button>
</div>
Note
Strings will be converted to datetime if they are successfully parsed by Django’s parse_datetime method.
Note
Enums themselves cannot be passed as an argument, but the enum value can be since that is a Python primitive. In the component’s view, use the enum’s constructor to convert the primitive back into the enum if needed.
# enum.py
from django_unicorn.components import UnicornView
from enum import Enum
class Color(Enum):
RED = 1
GREEN = 2
BLUE = 3
PURPLE = 4
class EnumView(UnicornView):
color = Color.RED
purple_color = Color.PURPLE
def set_color(self, color_int: int):
self.color = Color(color_int)
<!-- enum.html -->
<div>
<button unicorn:click="set_color({{ color.BLUE.value }})">Show BLUE (and 3) below when clicked</button>
<button unicorn:click="set_color(2)">Show GREEN (and 2) below when clicked</button>
<button unicorn:click="set_color({{ purple_color.value }})">Show PURPLE (and 4) below when clicked</button>
<br />
<!-- This will be RED when first rendered, and then will change based on the button clicked above -->
Color: {{ color }}
<br />
<!-- This will be 1 when first rendered, and then will change based on the button clicked above -->
Color int: {{ color.value }}
</div>
Set shortcut¶
Actions can also set properties without requiring an explicit method.
<!-- set-shortcut.html -->
<div>
<input unicorn:model="name" type="text" id="text" />
Hello {{ name|title }} 👋
<button unicorn:click="name='Bob'">Set name as Bob</button>
</div>
# set_shortcut.py
from django_unicorn.components import UnicornView
class SetShortcutView(UnicornView):
name = "World"
Modifiers¶
Similar to models, actions also have modifiers which change how the method gets called.
prevent¶
Prevents the default action the browser would use for that element. The same as calling preventDefault.
<!-- prevent-modifier.html -->
<div>
<button unicorn:click.prevent="name='Bob'">Set name as Bob</button>
</div>
stop¶
Stops the event from bubbling up the event chain. The same as calling stopPropagation.
<!-- stop-modifier.html -->
<div>
<button unicorn:click.stop="name='Bob'">Set name as Bob</button>
</div>
discard¶
Discards any model updates from being saved before calling the specified method on the view. Useful for a cancel button.
<!-- discard-modifier.html -->
<div>
<input type="text" unicorn:model="name">
<button unicorn:click.discard="cancel">Cancel</button>
</div>
# discard_modifier.py
from django_unicorn.components import UnicornView
class DiscardModifierView(UnicornView):
name = None
def cancel(self):
pass
debounce¶
Waits the specified time in milliseconds before calling the specified method.
<!-- debounce-modifier.html -->
<div>
<input type="text" unicorn:model="name">
<button unicorn:click.debounce-1000="add_count">Add Count</button>
</div>
Special arguments¶
$event¶
A reference to the event that triggered the action.
<!-- event.html -->
<div>
<input type="text" unicorn:change="update($event.target.value.trim())">Update</input>
</div>
$returnValue¶
A reference to the last return value from an action method.
<!-- returnValue.html -->
<div>
<input type="text" unicorn:change="update($returnValue.trim())">Update</input>
</div>
Special methods¶
$refresh¶
Refresh and re-render the component from its current state.
<!-- refresh-method.html -->
<div>
<button unicorn:click="$refresh">Refresh the component</button>
</div>
$reset¶
Revert the component to its original state.
<!-- reset-method.html -->
<div>
<button unicorn:click="$reset">Reset the component</button>
</div>
$toggle¶
Toggle a field on the component. Can only be used for fields that are booleans.
<!-- toggle-method.html -->
<div>
<button unicorn:click="$toggle('check')">Toggle the check field</button>
</div>
Tip
Multiple fields can be toggled at the same time by passing in multiple fields at a time: unicorn:click="$toggle('check', 'another_check', 'a_third_check')". Nested properties are also supported: unicorn:click="$toggle('nested.check')".
$validate¶
Validates the component.
<!-- validate-method.html -->
<div>
<button unicorn:click="$validate">Validate the component</button>
</div>
Calling methods¶
Sometimes you need to trigger a method on a component from regular JavaScript. That is possible with Unicorn.call(). The first argument is the name (or key) of the component and the second argument is the name of the method to call.
<!-- call-with-component-name.html -->
{% unicorn 'hello-world' %}
<button onclick="Unicorn.call('hello-world', 'set_name');">
Set the name from outside the component
</button>
<!-- call-with-component-key.html -->
{% unicorn 'hello-world' key='hello-universe' %}
<button onclick="Unicorn.call('hello-universe', 'set_name');">
Set the name from outside the component
</button>
Passing arguments the method call is also supported.
<!-- index.html -->
{% unicorn 'hello-world' %}
<button onclick="Unicorn.call('hello-world', 'set_name', 'World');">
Set the name to "World" from outside the component
</button>
Return values¶
To retrieve the last action method’s return value, use Unicorn.getReturnValue().
<!-- index.html -->
{% unicorn 'hello-world' %}
<button onclick="alert(Unicorn.getReturnValue('hello-world'));">
Get the last return value
</button>