General Component API

See below for an overview of the various possibilities Matestack provides for component implementation:

Response

Use the response method to define the UI of the component by using other components.

class Some::Component < Matestack::Ui::Component
def response
div id: "my-component" do
plain "hello world!"
end
end
end
class ExamplePage < Matestack::Ui::Page
def response
div id: "div-on-page" do
some_component
end
end
end

This is the HTML which gets created:

<div id="div-on-page">
<div id="my-component">
hello world!
</div>
</div>

If no response method is defined, matestack will look for a corresponding HAML template file lying next to Ruby component file.

Prepare

Use a prepare method to resolve data before rendering a component!

class Some::Component < Matestack::Ui::Component
def prepare
@some_data = "some data"
end
def response
div id: "my-component" do
plain @some_data
end
end
end
class ExamplePage < Matestack::Ui::Page
def response
div id: "div-on-page" do
some_component
end
end
end

This is the HTML which gets created:

<div id="div-on-page">
<div id="my-component">
some data
</div>
</div>

The prepare method comes in handy to read from the database or to resolve content before displaying it!

Params access

A component can access request information, e.g. url query params, by calling the params method:

class Some::Component < Matestack::Ui::Component
def response
div id: "my-component" do
plain params[:foo]
end
end
end

On the example page, reference the component as usual.

class ExamplePage < Matestack::Ui::Page
def response
div id: "div-on-page" do
some_component
end
end
end

Now, visiting the respective route to the page, e.g. via /xyz?foo=bar, the component reads the [:foo] from the params and displays it like so:

<div id="div-on-page">
<div id="my-component">
bar
</div>
</div>

Passing options to components

Define optional and required properties

Matestack components give you the option to define required and optional properties for a component. It creates helpers for these properties automatically.

Requires

Required properties are required for your component to work, like the name suggests. If at least one required property is missing a Matestack::Ui::Core::Properties::PropertyMissingException is raised.

Declare your required properties by calling requires as follows:

class SomeComponent < Matestack::Ui::Component
requires :some_property, :some_other
end

You then can use these properties simply by calling the provided helper method, which is generated for you. The helper method name corresponds to the passed property name.

class SomeComponent < Matestack::Ui::Component
requires :some_property, :some_other
def response
# display some_property plain inside a div and some_other property inside a paragraph beneath it
div do
plain some_property
end
paragraph text: some_other
end
end

Optional

To define optional attributes you can use the same syntax as requires. Just use optional instead of requires. Optional attributes are optional and not validated for presence like required attributes.

class SomeComponent < Matestack::Ui::Component
optional :optional_property, :other_optional_property optional properties could be empty
def response
# display optional_property plain inside a div and other_optional_property property inside a paragraph beneath it
div do
plain optional_property
end
paragraph text: other_optional_property
end
end

Passing properties to components

Pass the properties as a hash directly to the component when calling it. You can pass any object you like and use it in the component with the helper.

class SomeComponent < Matestack::Ui::Component
requires :some_option,
optional :some_other optional properties could be empty
def response
div do
plain some_option
end
if some_other.present?
paragraph text: some_other[:option]
end
end
end

Use it in the example page and pass in the properties as a hash

class ExamplePage < Matestack::Ui::Page
def prepare
@hello = "hello!"
end
def response
div id: "div-on-page" do
some_component some_option: @hello, some_other: { option: "world!" }
end
end
end

The outcome is quite as expected:

<div id="div-on-page">
<div>
hello!
</div>
<p>world!</p>
</div>

Alias properties

Matestack tries to prevent overriding existing methods while creating helpers. If you pass a property with a name that matches any instance method of your component matestack will raise a Matestack::Ui::Core::Properties::PropertyOverwritingExistingMethodException. To use property names that would raise this exception, simply provide an alias name with the as: option. You can then use the alias accordingly.

class SomeComponent < Matestack::Ui::Component
requires :foo, :bar, method: { as: :my_method }
optional response: { as: :my_response }
def response
div do
plain "#{foo} - #{bar} - #{my_method}" string concatenation of properties foo, bar, and method aliased as my_method
end
paragraph my_response if my_response.present? response property aliased as my_response inside a paragraph if it is present
end
end

Some common names that could not be used as properties:

:method,
:params

Arguments

If no hash was given, a component can also access/accept a simple argument!

class Components::Some::Component < Matestack::Ui::Component
def response
div id: "my-component" do
plain @argument
end
end
end

Just make sure to pass an argument on the example page:

class ExamplePage < Matestack::Ui::Page
def response
div id: "div-on-page" do
simply pass a string here
some_component "foo from page"
end
end
end

No miracle to find here, just what was expected!

<div id="div-on-page">
<div id="my-component">
foo from page
</div>
</div>

Yielding inside components

Components can yield a block with access to scope, where a block is defined. This works the way yield usually works in Ruby. But make sure to explicitly call 'yield_components' within the component response!

class Some::Component < Matestack::Ui::Component
def response
div id: "my-component" do
yield_components
end
end
end

Pass a block to a component on the page as shown below:

class ExamplePage < Matestack::Ui::Page
def prepare
@foo = "foo from page"
end
def response
div id: "div-on-page" do
some_component do
plain @foo
end
end
end
end

Not a fancy example, but this is the result:

<div id="div-on-page">
<div id="my-component">
foo from page
</div>
</div>

Partials

Use partials to keep the code dry and indentation layers manageable!

Local partials on component level

In the component definition, see how this time from inside the response, the my_partial method below is called:

class Some::Component < Matestack::Ui::Component
def response
div id: "my-component" do
my_partial "foo from component"
end
end
def my_partial text
plain text
end
end

As everything is already defined in the component, calling the some_component on the example page is all there is to do:

class ExamplePage < Matestack::Ui::Page
def response
div id: "div-on-page" do
custom_some_component
end
end
end

The outcome is the usual, boring HTML response. Below the HTML snippet, a more exciting example of partial usage is waiting!

<div id="div-on-page">
<div id="my-component">
foo from component
</div>
</div>

Modules: Partials on steriods!

Extract code snippets to modules for an even better project structure. First, create a module:

module MySharedPartials
def my_partial text
plain text
end
end

Include the module in the component:

class Some::Component < Matestack::Ui::Component
include MySharedPartials
def response
div id: "my-component" do
my_partial "foo from component"
end
end
end

Then reference the component on the example page as before:

class ExamplePage < Matestack::Ui::Page
def response
div id: "div-on-page" do
some_component
end
end
end

The output is unspectacular in this example, but more complex codebases will greatly benefit from this refactoring option!

<div id="div-on-page">
<div id="my-component">
foo from component
</div>
</div>

Try combining partials with options and slots (see below) for maximum readability, dryness and fun!

Slots

Similar to named slots in Vue.js, slots in Matestack allows us to inject whole UI snippets into the component. It's a more specific yielding mechanism as you will yield multiple "named" blocks into the component. Each of these blocks can be referenced and positioned independently in the component,

Slots on the page instance scope

Define the slots within the component file as shown below. Please make sure to inject slots within a hash slots: { ... } into the component.

class Some::Component < Matestack::Ui::Component
requires :slots
def prepare
@foo = "foo from component"
end
def response
div id: "my-component" do
slot slots[:my_first_slot]
br
slot slots[:my_second_slot]
end
end
end

Slots have access to the scope of the class, where they are defined. In this case @foo

class ExamplePage < Matestack::Ui::Page
def prepare
@foo = "foo from page"
end
def response
div do
some_component slots: {
my_first_slot: my_simple_slot,
my_second_slot: my_second_simple_slot
}
end
end
def my_simple_slot
slot do
span id: "my_simple_slot" do
plain "some content"
end
end
end
def my_second_simple_slot
slot do
span id: "my_simple_slot" do
plain @foo
end
end
end
end

This gets rendered into HTML as shown below. Notice that the @foo from the component configuration got overwritten by the page's local @foo!

<div>
<div id="my-component">
<span id="my_simple_slot">
some content
</span>
<br/>
<span id="my_simple_slot">
foo from page
</span>
</div>
</div>

Using slots of components within components

To use component instance scope slots, first define slots within a static component:

class Other::Component < Matestack::Ui::Component
requires :slots
def prepare
@foo = "foo from other component"
end
def response
div id: "my-other-component" do
slot slots[:my_slot_from_component]
br
slot slots[:my_slot_from_page]
br
plain @foo
end
end
end

and also in some component:

class Some::Component < Matestack::Ui::Component
requires :slots
def prepare
@foo = "foo from component"
end
def response
div id: "my-component" do
other_component slots: {
my_slot_from_component: my_slot_from_component,
my_slot_from_page: slots[:my_slot_from_page]
}
end
end
def my_slot_from_component
slot do
span id: "my-slot-from-component" do
plain @foo
end
end
end
end

Then, put both components (note that some component uses other component so that's how they're both in here) to use on the example page:

class ExamplePage < Matestack::Ui::Page
def prepare
@foo = "foo from page"
end
def response
div id: "page-div" do
some_component slots: { my_slot_from_page: my_slot_from_page }
end
end
def my_slot_from_page
slot do
span id: "my-slot-from-page" do
plain @foo
end
end
end
end

This gets rendered into the HTML below:

<div id="page-div">
<div id="my-component">
<div id="my-other-component">
<span id="my-slot-from-component">
foo from component
</span>
<br/>
<span id="my-slot-from-page">
foo from page
</span>
<br/>
foo from other component
</div>
</div>
</div>

This may seem complicated at first, but it can provide valuable freedom of configuration and great fallbacks in more complex scenarios!