Add Model Property

This skill walks through the complete workflow of adding a property to a data model, including generation and propagation to client/server.

When to Use

• Adding a new field to an existing entity
• Extending a model with additional properties
• Adding enum types to models
• Modifying entity data structures

CRITICAL Warning

NEVER edit generated model files! Only edit source models in /model/*.model/src/

Generated files (DO NOT EDIT):

• /client/libs/*/model/ ❌
• /server/com.*.model/ ❌

Source files (EDIT HERE):

• /model/*.model/src/ ✅

Reference: MODEL_GENERATION_GUIDE.md - Critical Concepts

Process

Step 1: Locate the Source Model

Find the model file in /model/*/src/:

# Example: Find InitConfig model
grep -r "export class InitConfig" /workspaces/faad-hmi/model/*/src/

Step 2: Choose Property Type

Determine the appropriate property type:

Property Types:

• ValueProperty<T> - Read-only from server (timestamps, computed values)
• CommandedProperty<T> - User can request changes (settings, modes)
• RangedCommandedProperty<T> - Numbers with min/max constraints
• RangedProperty<T> - Read-only numbers with constraints

Supported Types:

• string - Text values
• number - Numeric values (prefer RangedCommandedProperty if constrained)
• boolean - True/false flags
• EnumType - Custom enum types (must be defined separately)
• string[] - Arrays of entity IDs (ONLY string arrays supported!)
• Date - Timestamps (rare, usually use number for epoch)

Array Limitations (CRITICAL):

• ✅ string[] - Supported (for entity ID lists)
• ❌ number[] - NOT supported by generator
• ❌ boolean[] - NOT supported by generator
• ❌ EnumType[] - NOT supported by generator

Workaround for unsupported arrays: Create wrapper entities

// Instead of: values?: CommandedProperty<number[]>
// Create wrapper entity:
export class NumberValue extends Entity {
    value?: CommandedProperty<number>;
}
// Then use: valueIds?: CommandedProperty<string[]>

Reference: MODEL_GENERATION_GUIDE.md - Common Property Types

Step 3: Choose Property Name (CRITICAL)

Include units in property names! Comments don't transfer during generation.

Good Names:

• contourLineWidthPixels (not contourLineWidth)
• targetAltitudeMeters (not targetAltitude)
• speedKnots (not speed)
• brightnessPercentFraction (not brightness)
• intervalSeconds (not interval)

Common Unit Suffixes:

• Distance: Meters, Kilometers, Feet, Miles
• Screen: Pixels, Rem
• Angles: Degrees, Radians
• Time: Seconds, Milliseconds, Minutes
• Speed: Knots, Mph, Kph, MetersPerSecond
• Fractions: PercentFraction (0.0-1.0)
• Multipliers: Multiplier (e.g., terrainExaggerationMultiplier)

Reference: MODEL_GENERATION_GUIDE.md - Best Practices

Step 4: Edit Source Model

1. Add property to class
2. Add property name to "members" array in @description comment
3. Import any new types

Example:

/**
 * @description {
 *      "clazz" : {
 *          "extends": ["Entity"],
 *          "members": [
 *              "class",
 *              "existingProp1",
 *              "existingProp2",
 *              "newPropertyName"  // ← Add to members array!
 *          ]
 *      }
 * }
 */
export class MyModel extends Entity {
    /**
     * @default quicktype.projectname.MyModel
     */
    public static class: string = "quicktype.MyModel";

    existingProp1?: ValueProperty<string>;
    existingProp2?: CommandedProperty<number>;
    newPropertyName?: CommandedProperty<EnumType>;  // ← New property

    constructor(id: string) {
        super(id);
        this.className = MyModel.class;
    }
}

CRITICAL Class Name Pattern:

/**
 * @default quicktype.projectname.ClassName    // ✅ Include package
 */
public static class: string = "quicktype.ClassName";  // ❌ NO package

Reference: MODEL_GENERATION_GUIDE.md - Class/Entity Types

Step 5: Create Enum Type (If Needed)

If adding an enum property, create the enum file:

File: /model/projectname.model/src/yourEnumType.ts

/**
 * @description {
 *      "clazz" : {
 *         "enum": "VALUE1,VALUE2,VALUE3",
 *         "title":"YourEnumType"
 *      }
 * }
 * @type integer
 */
export enum YourEnumType {
    VALUE1 = 0,
    VALUE2 = 1,
    VALUE3 = 2
}

CRITICAL: Enum values must be globally unique across ALL enums!

• ❌ WRONG: Multiple enums with UNKNOWN (generator collision!)
• ✅ CORRECT: Use prefixes like UNKNOWN_KIND, UNKNOWN_SOURCE

Reference: MODEL_GENERATION_GUIDE.md - Enum Types

Step 6: Run Model Generation

npm run generate-model

This generates:

• TypeScript models in /client/libs/*/model/
• C# models in /server/com.*.model/

Check for errors - Common issues:

• Missing property in members array
• Enum not defined
• Invalid property type
• Circular dependencies

Reference: MODEL_GENERATION_GUIDE.md - Model Generation Workflow

Step 7: Update Entity ViewModel

IMPORTANT: Property changes flow through both client and server. See full data flow in CLIENT_SERVER_BRIDGE.md.

Add property ViewModel getter:

@computed
get newPropertyNameVM(): ICommandedVM<EnumType, IEnumFormatOptions<EnumType>> {
    const vm = this.createPropertyVM('newPropertyName', CommandedEnumViewModel<EnumType>);
    vm.configure({
        labelConverter: YourEnumTypeLabel,
        defaultValue: YourEnumType.VALUE1
    });
    return vm;
}

@computed Usage: Use @computed when getter includes configuration or derives values.

Create label converter in adapters/types.ts:

export const YourEnumTypeLabel: Record<YourEnumType, string> = {
    [YourEnumType.VALUE1]: 'Display Label 1',
    [YourEnumType.VALUE2]: 'Display Label 2',
};

References:

• ENTITY_ARCHITECTURE.md - Property ViewModel Patterns
• CLIENT_SERVER_BRIDGE.md - Cross-stack property lifecycle

Step 8: Update Server-Side Code (C#)

If this entity has server-side simulation/builder code:

1. Find builder class (usually *Builder.cs)
2. Add property initialization
3. Update any simulation logic that uses the entity

Example locations:

• /server/com.faad.runner/simulations/
• /server/com.faad.runner/builders/

Reference: SERVER.md

Step 9: Verify Build

# Check client-side errors
./tools/build-helpers/count-client-errors.sh
./tools/build-helpers/show-client-errors.sh 10

# Check server-side errors
./tools/build-helpers/count-server-errors.sh
./tools/build-helpers/show-server-errors.sh 10

All errors should be resolved.

Step 10: Update UI Components

If the property should be visible/editable in UI:

1. Find the view component
2. Add input component bound to property VM
3. Use appropriate Phoenix component (Select, TextInput, Checkbox, etc.)

Reference: UI_COMPONENT_GUIDELINES.md

Common Pitfalls

Reference: COMMON_PITFALLS.md

1. ❌ Editing generated files instead of source
2. ❌ Forgetting to add property to members array
3. ❌ Using unsupported array types (number[], boolean[])
4. ❌ Not including units in property names
5. ❌ Duplicate enum values across different enums
6. ❌ Forgetting to run npm run generate-model
7. ❌ Missing label converter for enum types

Verification Checklist

• Source model edited in /model/*/src/
• Property added to members array
• Enum created (if applicable) with unique values
• npm run generate-model ran successfully
• Entity ViewModel updated with property VM
• Label converter created (for enums)
• Server builder updated (if applicable)
• Build passes (0 client/server errors)
• UI component updated (if user-facing)
• Tests updated

Ask User If Unclear

• Property type (Value, Commanded, Ranged)
• Default value for the property
• Whether property should be visible/editable in UI
• Units for numeric properties
• Display labels for enum values