Composite components
Introduction
A composite component allows you to encapsulate a piece of an application screen into a coherent, reusable element. In the component, both the appearance of the screen area and its behavior are defined.
Teams using composite components to build user interfaces save time and make it easier to maintain frontend consistency.
Role and use cases
The main role of composite components is multiple reuse of repetitive form areas on different pages. Once created, a composite component can be embedded:
on different form pages – allowing many pages to use a shared, consistent part
multiple times on the same page – e.g., if a single form requires two independent address sections (for a registered address and a correspondence address).
This approach significantly speeds up application development and facilitates maintenance – a change in the composite component definition automatically affects all places where it is used.
This increases application consistency (the same components look and behave identically across different forms) and reduces the risk of errors arising from duplicating configuration. For example, if a form requires a repeating section with the same fields (like the mentioned address section), it is worth extracting it as a composite component and using it multiple times instead of creating those fields from scratch each time.
Composite components are often used in business applications as standard form sections (e.g., address data, contact data, sections with customer information, etc.), which ensures a uniform user experience and facilitates the development of subsequent forms.
Creating a component
To create a new composite component or edit an existing one, you should:
In Eximee Designer go to the module Library and select the tab Composite components,
in this view, a list of all available composite components in the repository is displayed along with management options,
From the list you can:
create a new component (button Add composite component),
copy or edit an existing artifact using the dropdown menu (three dots)
view the component’s version history using the dropdown menu (three dots)
Choose the option to add a new composite component
a create artifact window appears, in which we provide the component name and location (folder) in the project tree, similar to creating a new form.
After creating the composite component artifact, the composite component editoropens, very similar to the form editor. In the central part of the view, we design the layout and add the necessary fields and controls – you can drag base components (e.g., text fields, lists, buttons, etc.) onto the workspace or even nest other available composite components. In this way we define the internal structure of the new composite component. On the right side there is a properties panel where we configure attributes of the selected fields (just like in a form).
After configuring the content of the composite component, we save it by assigning an appropriate version (more on versioning below). Saving creates a new version of the artifact, which can be used in forms.
Parameters input
Composite components can accept input parameters, which allows passing values into them from the outside – from a form or even from another composite component.
To define an input parameter, in the composite component definition editor, select the option in the left panel Input parametersand then click Add input parameter. Each input parameter refers to some field or session variable from the embedding context of the component (i.e., it will expect a specific field/variable to be assigned when the component is used). When defining a parameter:
we indicate the source of the value (form field or variable),
optionally assign an alias (a friendly name displayed during mapping)
optionally provide a default value – used if no value is assigned during embedding.
It is possible to map values from fields of the parent form, fields from other composite components located on the same form, as well as session variables available in the form context.
Thanks to the input parameter mechanism, a composite component can be more universal – e.g., instead of referring internally to a specific global variable, it can accept a value as a parameter, which allows it to be used in different places with different data.
Embedding a component
A created composite component can be embedded in any form or even inside another composite component (nesting) – the platform allows any levels of nesting.
To use a composite component in a form, go to edit that form and then select the Compositetab from the component palette on the left. A list of all available composite components in the repository will be displayed (with the option to search by name). From this list, select the appropriate component and add it to the form by drag-and-drop to the desired place in the form structure.
After dropping, the composite component will be embedded in the form as a single logical whole – in the form structure tree, it will be visible as a single node containing the previously defined fields.
A composite component placed on the screen becomes its integral part. All fields it contains inherit the behavior of standard fields – e.g., required fields must be filled in, validators attached to fields inside the composite component work the same as for fields added directly to the form, etc.
If necessary, at the form level you can also define additional form validators that also cover fields inside composite components (e.g., a script checking the consistency of data between sections).
Similarly, navigation mechanisms or conditional visibility also apply to nested components – a composite component can, for example, be hidden or shown depending on a condition, analogous to a single field.
Versioning and change propagation
Versioning is described in detail here.
Interactions with other artifacts
A composite component does not function in a vacuum – it interacts with various elements of the platform
Forms
The basic “relationship” is embedding in a form, which has been discussed above. From the form’s point of view, a composite component is simply a form element – during application runtime, the end user does not see a difference between fields originating from a composite component and other fields. In the Translations tab of the form, all texts contained in embedded composite components are available for editing – this means that translations of labels and hints from the composite component can be overridden or adjusted at the level of a specific form, if necessary. A composite component is also treated as a constituent part of the application.
Validators
Fields within a composite component can use all validation mechanisms available for regular fields. If we assign a script validatorto any field inside the composite component, it will be executed the same as for a standard field on the form. Also visibility conditions or requiredness conditions can be defined for fields within a composite component – they will be respected after the component is embedded in the form. Moreover, validators defined at the entire form level (e.g., verifying dependencies between different fields) can refer to fields located in composite components. Such a field can be identified by its business identifier (mid) – composite components and their fields have business identifiers just like regular form fields, which makes it easier to reference them in scripts and configurations.
Formatted content
Composite components can also use content artifacts (TextContent), analogous to regular forms. If a section requires embedding a larger block of static text (e.g., terms, clauses, descriptions), you can add a control of type Formatted content in the composite component and attach a Content artifact containing the appropriate content (managed centrally). This allows a composite component to include not only data fields, but also informational elements or instructions for the user, making it a complete, reusable fragment of the user interface.
Services and variables
If, inside a composite component, session variables are used (e.g., to store transient values or service results), remember to prefix the names of these variables with the symbol in conditional expressions @. This will allow the platform to distinguish a session variable of the component from a session variable of the parent form.
In addition, session variables cannot be used directly in components of type Repeatable section inside a composite component – in such situations, it is recommended to use technical fields as a carrier of values.
If a composite component needs to use an external service (e.g., to fill its fields based on data from a database), it can call services just like a form. A service can be attached as a PageService in the component logic and, for example, called in response to an event (e.g., a field change). However, remember that services operate in the context of the entire application request, so invoking a service from the component level affects the parent form.
Good practices
Identifying reuse opportunities
Already at the requirements analysis stage, it is worth identifying form sections that may appear multiple times or in many different application forms. Such sections (e.g., address data, customer personal data, contact information section, consent sections, etc.) should be designed as separate composite components, instead of duplicating the same fields in many places. This makes development easier (the section is created once) and maintenance easier (modifying the section in one place updates it everywhere it is used).
Naming and organization
Use consistent naming for artifacts. A composite component should have a name that clearly indicates its content or purpose. It is common to use a convention of prefixing component names with a prefix related to the application or business module, e.g., crmCustomerAddress, insVehicleData – this makes it easier to identify in the repository which area a given component belongs to. Also keep order in the directory structure in the Library – it is worth grouping composite components into thematic or project folders.
Documenting the component
Each composite component can be provided with internal documentation. In the tab of the Properties composite component editor, there is a “Documentation” section where you can describe the operation and purpose of the component (it supports HTML formatting). It is recommended to fill in the documentation for the component – especially if it will be used by many developers or in many places – so that platform users know how to use it correctly and what its potential dependencies are. Good documentation facilitates reuse of the component and speeds up onboarding of new team members.
Versioning and backward compatibility
When planning changes to a composite component, consider their impact on existing forms. Avoid introducing breaking changes without bumping the major version (MAJOR). If a change to the structure or behavior of the component is necessary that could disrupt the operation of forms using it, it is better to create a new version branch. After modifications, test the composite component in all critical scenarios – especially when the component is used in many places.
Avoiding excessive complexity
Although composite components can contain any logic, try to ensure that they perform a relatively uniform, clearly defined function. Avoid creating one huge composite component that handles many unrelated tasks – it is better to split it into smaller, more specialized sections. Excessive nesting of composite components (component within component within component, etc.) can also make debugging and understanding the form more difficult – use this capability judiciously, guided by the readability of the form structure.
Be careful when copying components
The platform allows duplication of a composite component (the Duplicate option in the composite components list) – this is useful when you want to create a similar component based on an existing one. However, make sure how nested components are treated during copying. If the copied composite component contained other composite components, the copy will not create their duplicates – references to the original artifacts will be preserved. You need to consider whether in the new component you still want to use those original, shared sub-components, or whether you should copy them as well (e.g., when changes in them should not affect our new component). This is important from a maintenance perspective – unknowingly editing a nested component can affect other places where it is used.
Using existing components
Check whether the composite component you need already exists in the library – especially in larger organizations a catalog of shared components may be created. Using already prepared, tested components (e.g., user authorization components, a downloadable documents component, GDPR consent sections, etc.) is faster and safer than creating your own from scratch. Build new composite components when the required functionality is indeed missing in the existing resources.
UX consistency
Remember that a composite component is part of the user interface – design it in accordance with the UX/UI standards in your organization. Ensure that the layout of fields, their labels, hints, as well as validations and error messages within the component are consistent with the rest of the form. This way, the user will not feel that a given section has been “glued on” from elsewhere. Use the translations mechanism for static texts in the component, fill in their keys and values – this will make it easier to manage literals from the application level.
Example
The illustrations below show an example of a composite component named demoAddress and how to use it. First, a composite component containing address fields (street, city, postal code) was designed – it serves as a template for an address section:
Then the same component demoAddress was embedded three times in a sample form (e.g., for registered address, correspondence address, and workplace address) – by reusing a single artifact, we obtain three sections in the form without having to create three sets of fields separately:
As a result, in the user interface the form displays three uniform address sections using the same composite component:
The above example illustrates how composite components simplify building repetitive parts of an application – modifying the component demoAddress (e.g., adding a “Country” field) will automatically introduce this field into all three address sections on the form. This makes managing complex forms easier, and shared parts of the application remain consistent in all places of use.
Using the above tips and best practices, Eximee composite components make it possible to efficiently create modular, easy-to-maintain business applications in which once-defined sections can be used across many processes and forms. Well-designed composite components pay off by reducing duplication of work, unifying the interface, and enabling faster implementation of changes in the future.
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