ui5-best-practices-mdc

UI5 MDC Controls Best Practices

Apply these guidelines whenever generating, reviewing, or troubleshooting MDC control code in freestyle applications using OData V4 services.

UI5 version baseline: SAPUI5 1.136+ LTS. All features mentioned are available from this version unless noted.

When to load each reference

Trigger	Load
Working on or planning a sap.ui.mdc.FilterBar	references/mdc-filter-bar.md
Working on or planning a sap.ui.mdc.Chart	references/mdc-chart.md
Working on or planning a sap.ui.mdc.Field	references/mdc-field.md
Working on or planning a sap.ui.mdc.FilterField	references/mdc-filter-field.md
Working on or planning a sap.ui.mdc.ValueHelp	references/mdc-value-help.md
Working on or planning a sap.ui.mdc.Link	references/mdc-link.md
Working on or planning a sap.ui.mdc.MultiValueField	references/mdc-multi-value-field.md
Using MDC controls with JSON model (non-OData)	references/mdc-json-delegates.md
Working on or planning a sap.ui.mdc.Table	See ui5-best-practices-tables skill, references/mdc-table.md

Load before producing any output. Do not work from memory.

---

The Delegate Pattern

All MDC controls use a delegate to decouple the control from data-source-specific logic. App developers must:

1. Specify the delegate in XML: delegate="{name: 'my/app/delegate/MyDelegate', payload: {entitySet: 'Products'}}"
2. Implement the delegate module extending the appropriate base delegate
3. Override key methods (at minimum fetchProperties)

Base delegates for OData V4:

Control	Base Delegate
Table	sap/ui/mdc/odata/v4/TableDelegate
FilterBar	sap/ui/mdc/odata/v4/FilterBarDelegate
Chart	sap/ui/mdc/odata/v4/vizChart/Delegate
ValueHelp	sap/ui/mdc/ValueHelpDelegate
Link	sap/ui/mdc/LinkDelegate
MultiValueField	sap/ui/mdc/field/MultiValueFieldDelegate

JSON model usage: MDC controls also work with JSON models. Extend the base delegates directly (sap/ui/mdc/TableDelegate, sap/ui/mdc/FilterBarDelegate) — not the OData V4 variants. See references/mdc-json-delegates.md for details.

PropertyInfo — the core metadata format returned by fetchProperties:

{
    key: "propertyName",        // Unique identifier (required)
    label: "Display Label",     // User-visible label (required)
    dataType: "sap.ui.model.odata.v4.type.String"  // Data type (required)
}

---

Core Rules

Mandatory

• Every MDC control requires a delegate property pointing to a valid module path.
• Implement fetchProperties in the delegate returning PropertyInfo[] with at minimum: key, label, dataType.
• Extend the appropriate OData V4 base delegate (see table above) for OData V4 services. For JSON/other models, extend the generic base delegate directly.
• Use p13nMode to enable personalization (Column, Sort, Filter, Group for Table; Item, Sort, Filter, Type for Chart; Item for FilterBar).
• Use sap.ui.mdc.condition.Condition.createCondition() to construct conditions programmatically.
• Use sap.ui.model.odata.v4.type.* types in PropertyInfo dataType field for OData V4 models. Use sap.ui.model.type.* with JSON models. Register types in the TypeMap.
• Set ariaLabelledBy on FilterBar and Chart for accessibility.
• Prefer Fiori elements building blocks over freestyle MDC. Use MDC only when Fiori elements is out of scope.
• Use get_api_reference MCP tool to verify control APIs. Use run_ui5_linter to validate code.

Prohibitions

• Do not use MDC controls with OData V2 models. Use Smart controls (sap.ui.comp) instead. MDC works with OData V4 and JSON models.
• Do not access inner controls directly (e.g., inner sap.chart.Chart or sap.m.Table). Use the delegate or MDC control's public API.
• Do not omit key from PropertyInfo objects (formerly name, now deprecated).
• Do not construct condition objects manually as plain JSON. Always use Condition.createCondition(operator, values).
• Do not skip delegate implementation for production code (built-in defaults are for demos only).
• Do not use inline styles or scripts (CSP compliance).
• Do not use global access (sap.ui.mdc.FilterBar). Use sap.ui.define or ES6 imports.

---

Selection Matrix

Control	Use when	Do not use when
MDC FilterBar	OData V4 or JSON model, delegate-driven filter UI, MDC Table/Chart	OData V2 (use SmartFilterBar), simple search bar
MDC Chart	OData V4, delegate-driven chart visualization, drill-down	OData V2 (use SmartChart), simple static charts, no analytical data
MDC Field	OData V4 or JSON, single field with auto-rendering by data type	OData V2 (use SmartField), purely custom rendering needed
MDC FilterField	Inside MDC FilterBar for individual filter conditions	Standalone filtering outside FilterBar context
MDC ValueHelp	OData V4 or JSON, type-ahead + dialog value selection	OData V2 (use ValueHelpDialog), simple dropdowns without search
MDC Link	OData V4, semantic object navigation, delegate-driven link targets	OData V2 (use SmartLink), simple static links
MDC MultiValueField	OData V4 or JSON, multi-value token entry via items aggregation	OData V2 (use SmartMultiInput), simple single-value fields

---

Common Errors

Symptom	Cause	Fix
"Delegate module could not be loaded"	Wrong path in delegate property	Verify module path matches actual file location in project.
Chart shows no data	fetchProperties returns wrong PropertyInfo (missing groupable/aggregatable)	Ensure dimensions have groupable: true, measures have aggregatable: true.
FilterBar fields not appearing	PropertyInfo missing or hiddenFilter: true	Check delegate fetchProperties returns properties with correct visibility.
Field shows wrong inner control	dataType in PropertyInfo doesn't match expected format	Verify dataType uses full qualified type name (e.g., sap.ui.model.odata.v4.type.String).
Personalization dialog empty	p13nMode not set or PropertyInfo incomplete	Add p13nMode="Column,Sort,Filter" and ensure PropertyInfo has sortable/filterable flags.
ValueHelp not opening	ValueHelp not connected to Field or containers missing	Verify valueHelp association on Field and that Popover/Dialog containers are defined.
Conditions not applied to binding	updateBindingInfo not implemented in delegate	Implement updateBindingInfo to apply filter conditions to the OData binding.
Link always rendered as text	fetchLinkType returns LinkType.Text or fails	Implement fetchLinkType returning Popup or DirectLink type.

---

Performance & Accessibility

Anti-patterns to avoid

• Loading all PropertyInfo eagerly when only a subset is needed (return minimal set from fetchProperties).
• Not implementing updateBindingInfo (conditions are never applied to the data binding).
• Skipping p13nMode configuration (personalization features are disabled by default).
• Creating large delegate modules (split complex logic into helper modules loaded on demand).
• Using synchronous operations in delegate methods (all delegate methods should return Promises).

Accessibility checklist

• Set ariaLabelledBy on FilterBar referencing a visible title.
• Set ariaLabelledBy on Chart referencing a visible title.
• Verify keyboard navigation works for personalization dialogs.
• Test ValueHelp type-ahead and dialog with screen reader.
• Ensure all FilterFields have meaningful labels via PropertyInfo label.