RAP Side Effects: Automatic UI Updates

Why Side Effects?

Side Effects answer questions like:

Which fields need to be updated when the price changes?
Which UI areas need to reload after an action?
How are calculated fields automatically updated?

Typical Use Cases

Scenario	Trigger	Affected Fields
Price calculation	Quantity, Unit Price	Total Price
Date calculation	Start or End Date	Duration, Work Days
Currency conversion	Currency	All Amount Fields
Status change	Action execution	Status, Availability

Side Effects in the Behavior Definition

Side Effects are defined declaratively in the Behavior Definition:

managed implementation in class zbp_i_travel unique;
strict ( 2 );

define behavior for ZI_Travel alias Travel
persistent table ztravel
lock master
authorization master ( instance )
etag master LastChangedAt
{
  create;
  update;
  delete;

  // Side Effects Block
  side effects
  {
    // Field-Level Side Effects
    field BeginDate affects field Duration;
    field EndDate affects field Duration;

    // Action-Level Side Effects
    action calculatePrice affects field TotalPrice, field Currency;

    // Determination Side Effects
    determine action Prepare affects field Status;
  }
}

Field-Level Side Effects

Field-Level Side Effects define which fields are updated when a specific field changes.

Simple Field Side Effect

side effects
{
  // When BeginDate changes, update Duration
  field BeginDate affects field Duration;

  // When EndDate changes, update Duration
  field EndDate affects field Duration;
}

Multiple Trigger Fields

side effects
{
  // Multiple fields trigger the same update
  field ( BeginDate, EndDate ) affects field Duration;

  // Price calculation on quantity or price change
  field ( Quantity, UnitPrice ) affects field TotalPrice;
}

Multiple Affected Fields

side effects
{
  // One trigger field affects multiple target fields
  field Quantity affects field TotalPrice, field TaxAmount, field NetPrice;

  // Currency change affects all amount fields
  field CurrencyCode affects field TotalPrice, field TaxAmount, field Discount;
}

$self - The Entire Instance

With $self, the entire instance is marked as affected:

side effects
{
  // Currency change: Reload all fields
  field CurrencyCode affects $self;

  // Customer change: Update entire instance
  field CustomerId affects $self;
}

Action-Level Side Effects

Action-Level Side Effects define which fields are updated after an action.

define behavior for ZI_Travel alias Travel
{
  // Define actions
  action calculatePrice result [1] $self;
  action applyDiscount result [1] $self;
  action setStatus result [1] $self;

  side effects
  {
    // After price calculation, update these fields
    action calculatePrice affects field TotalPrice, field TaxAmount;

    // After discount application
    action applyDiscount affects field TotalPrice, field DiscountAmount;

    // Status change affects Status field
    action setStatus affects field Status;
  }
}

Action with Complex Side Effects

side effects
{
  // Action affects multiple areas
  action recalculateAll affects
    field TotalPrice,
    field TaxAmount,
    field NetPrice,
    field Currency,
    entity _Bookings;  // Also associations

  // Action affects entire entity
  action copyFromTemplate affects $self;
}

Determination Side Effects

When Determinations are executed, Side Effects can inform the UI about calculated values.

Behavior Definition

define behavior for ZI_Travel alias Travel
{
  // Determination for price calculation
  determination calculateTotalPrice on modify { field Quantity; field UnitPrice; }

  // Determination for status
  determination setInitialStatus on modify { create; }

  side effects
  {
    // When calculateTotalPrice executes on Quantity change
    determine action calculateTotalPrice executed on field Quantity
      affects field TotalPrice;

    // When calculateTotalPrice executes on UnitPrice change
    determine action calculateTotalPrice executed on field UnitPrice
      affects field TotalPrice;
  }
}

Complete Example with Determination

managed implementation in class zbp_i_travel unique;
strict ( 2 );

define behavior for ZI_Travel alias Travel
persistent table ztravel
{
  create;
  update;
  delete;

  // Determinations
  determination calculateDuration on modify { field BeginDate; field EndDate; }
  determination calculatePrice on modify { field Quantity; field UnitPrice; field CurrencyCode; }

  side effects
  {
    // Duration calculation
    determine action calculateDuration executed on field BeginDate
      affects field Duration;
    determine action calculateDuration executed on field EndDate
      affects field Duration;

    // Price calculation
    determine action calculatePrice executed on field Quantity
      affects field TotalPrice, field TaxAmount;
    determine action calculatePrice executed on field UnitPrice
      affects field TotalPrice, field TaxAmount;
    determine action calculatePrice executed on field CurrencyCode
      affects field TotalPrice, field TaxAmount, field Currency;
  }
}

Determination Implementation

CLASS lhc_travel DEFINITION INHERITING FROM cl_abap_behavior_handler.
  PRIVATE SECTION.
    METHODS calculateDuration FOR DETERMINE ON MODIFY
      IMPORTING keys FOR Travel~calculateDuration.

    METHODS calculatePrice FOR DETERMINE ON MODIFY
      IMPORTING keys FOR Travel~calculatePrice.
ENDCLASS.

CLASS lhc_travel IMPLEMENTATION.
  METHOD calculateDuration.
    READ ENTITIES OF zi_travel IN LOCAL MODE
      ENTITY Travel
        FIELDS ( BeginDate EndDate )
        WITH CORRESPONDING #( keys )
      RESULT DATA(lt_travel).

    MODIFY ENTITIES OF zi_travel IN LOCAL MODE
      ENTITY Travel
        UPDATE FIELDS ( Duration )
        WITH VALUE #( FOR ls_travel IN lt_travel
          WHERE ( BeginDate IS NOT INITIAL AND EndDate IS NOT INITIAL )
          ( %tky     = ls_travel-%tky
            Duration = ls_travel-EndDate - ls_travel-BeginDate ) )
      REPORTED reported.
  ENDMETHOD.

  METHOD calculatePrice.
    READ ENTITIES OF zi_travel IN LOCAL MODE
      ENTITY Travel
        FIELDS ( Quantity UnitPrice CurrencyCode )
        WITH CORRESPONDING #( keys )
      RESULT DATA(lt_travel).

    MODIFY ENTITIES OF zi_travel IN LOCAL MODE
      ENTITY Travel
        UPDATE FIELDS ( TotalPrice TaxAmount Currency )
        WITH VALUE #( FOR ls_travel IN lt_travel
          LET lv_total = ls_travel-Quantity * ls_travel-UnitPrice
              lv_tax   = lv_total * '0.19'
          IN
          ( %tky       = ls_travel-%tky
            TotalPrice = lv_total
            TaxAmount  = lv_tax
            Currency   = ls_travel-CurrencyCode ) )
      REPORTED reported.
  ENDMETHOD.
ENDCLASS.

Side Effects with Associations

Side Effects can also affect associations:

define behavior for ZI_Travel alias Travel
{
  association _Bookings { create; }

  side effects
  {
    // Changes to Bookings affect Travel
    field _Bookings affects field TotalPrice, field BookingCount;

    // Currency change in Travel affects all Bookings
    field CurrencyCode affects entity _Bookings;
  }
}

define behavior for ZI_Booking alias Booking
{
  association _Travel;

  side effects
  {
    // Price in Booking affects total price in Travel
    field Price affects field _Travel.TotalPrice;
  }
}

Hierarchical Side Effects

define behavior for ZI_Travel alias Travel
{
  side effects
  {
    // Update all Bookings when currency changes
    field CurrencyCode affects entity _Bookings, entity _Passengers;

    // After Copy action, reload all child entities
    action copyWithDetails affects $self, entity _Bookings, entity _Passengers;
  }
}

Target Fields and $self

Single Target Fields

side effects
{
  field Quantity affects field TotalPrice;
}

Multiple Target Fields

side effects
{
  field Quantity affects field TotalPrice, field TaxAmount, field NetPrice;
}

Entire Entity ($self)

side effects
{
  // On status change: Reload complete instance
  field Status affects $self;

  // On copy: Update everything
  action copy affects $self;
}

Entity (Associations)

side effects
{
  // Update child entities
  field CurrencyCode affects entity _Bookings;

  // Update parent entity
  field BookingPrice affects entity _Travel;
}

Complete Example

managed implementation in class zbp_i_travel unique;
strict ( 2 );

define behavior for ZI_Travel alias Travel
persistent table ztravel
draft table zdraft_travel
lock master total etag LastChangedAt
authorization master ( instance )
etag master LastChangedAt
{
  create;
  update;
  delete;

  // Fields
  field ( readonly ) TravelId, CreatedBy, CreatedAt;
  field ( mandatory ) CustomerId;

  // Associations
  association _Bookings { create; }

  // Determinations
  determination calculateDuration on modify { field BeginDate; field EndDate; }
  determination calculateTotalPrice on modify { field _Bookings; }
  determination setInitialStatus on modify { create; }

  // Actions
  action ( features: instance ) acceptTravel result [1] $self;
  action recalculatePrice result [1] $self;

  // Side Effects
  side effects
  {
    // Field-Level
    field BeginDate affects field Duration, field DaysUntilStart;
    field EndDate affects field Duration;
    field CustomerId affects field CustomerName, field CustomerRating;

    // Currency affects all amount fields
    field CurrencyCode affects
      field TotalPrice,
      field TaxAmount,
      entity _Bookings;

    // Determination Side Effects
    determine action calculateDuration executed on field BeginDate
      affects field Duration;
    determine action calculateDuration executed on field EndDate
      affects field Duration;
    determine action calculateTotalPrice executed on field _Bookings
      affects field TotalPrice, field BookingCount;

    // Action Side Effects
    action acceptTravel affects field Status, field ApprovedAt, field ApprovedBy;
    action recalculatePrice affects field TotalPrice, field TaxAmount, entity _Bookings;
  }
}

define behavior for ZI_Booking alias Booking
persistent table zbooking
draft table zdraft_booking
lock dependent by _Travel
authorization dependent by _Travel
etag master LastChangedAt
{
  create;
  update;
  delete;

  association _Travel;

  side effects
  {
    // Price change in Booking updates Travel total
    field Price affects field _Travel.TotalPrice;
  }
}

Best Practices

Minimal Side Effects: Define only the Side Effects that are truly needed - too many can impact performance
Specific Fields Instead of $self: Use $self only when the entire entity is actually affected
Determination + Side Effect: Combine Determinations with Side Effects for automatic calculations
Bidirectional Associations: Pay attention to the correct direction of Side Effects in parent-child relationships
Performance: Side Effects trigger UI requests - test performance in complex scenarios
Consistency: Ensure Side Effect definitions match the actual logic

" CORRECT: Side Effect matches the Determination
determination calculateTotal on modify { field Quantity; field Price; }
side effects
{
  determine action calculateTotal executed on field Quantity affects field TotalPrice;
  determine action calculateTotal executed on field Price affects field TotalPrice;
}

" WRONG: Side Effect without corresponding calculation
side effects
{
  field Quantity affects field TotalPrice;  " Who calculates TotalPrice?
}

RAP Feature Control - Dynamic UI control
RAP Determinations & Validations - Automatic calculations
RAP Draft Handling - Intermediate saving