Lesson 3 Practice — Connection Modeling

In Lesson 3, you created:

/DMO/FLIGHT
      ↓
ZI_FLIGHT_###
      ↓
calculated elements
      ↓
ZI_AVAILABLE_FLIGHT_###
      ↓
filtered model

In this practice, apply the same ideas to:

/DMO/CONNECTION

Your target architecture is:

/DMO/CONNECTION
      ↓
ZI_CONNECTION_###
  ├─ RouteCode
  └─ DeparturePeriod
      ↓
ZI_MORNING_CONNECTION_###
      ↓
Connection Reader
      ↓
Runner

This assignment does not contain the complete source solution.

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Objects to create

Create:

ZI_CONNECTION_###
ZI_MORNING_CONNECTION_###
ZCL_CONNECTION_READER_###
ZCL_CDS_L03_PRACTICE_###

Replace ### with your student/group suffix.

---

Part 1 — Explore /DMO/CONNECTION

Open:

/DMO/CONNECTION

with:

Ctrl + Shift + A

Identify:

carrier_id
connection_id
airport_from_id
airport_to_id
departure_time
arrival_time
distance
distance_unit

Confirm that the key is:

carrier_id + connection_id

Open Data Preview.

Record at least three connections with different departure times.

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Part 2 — Plan the model

Your base CDS model should expose:

CarrierId
ConnectionId
AirportFromId
AirportToId
DepartureTime
ArrivalTime
Distance
DistanceUnit
RouteCode
DeparturePeriod

Two elements must be derived:

RouteCode
DeparturePeriod

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Part 3 — Define RouteCode

Use the CDS built-in function:

CONCAT_WITH_SPACE

Combine:

AirportFromId
AirportToId

with one space between them.

Example result:

FRA JFK

Hint

The function shape is:

concat_with_space(
  <first value>,
  <second value>,
  1
)

Answer:

Why is RouteCode a calculated element rather than a persisted field?

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Part 4 — Define DeparturePeriod

Classify each connection using its departure time.

Rules:

before 12:00 → Morning
before 18:00 → Afternoon
otherwise    → Evening

Use a searched CASE expression.

Use typed time literals:

abap.tims'120000'
abap.tims'180000'

Use typed character literals for the result values.

Hint

The structure is:

case
  when ...
    then ...
  when ...
    then ...
  else ...
end as DeparturePeriod

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Part 5 — Create ZI_CONNECTION_###

Create a Data Definition.

Use:

Name:        ZI_CONNECTION_###
Description: Lesson 3 - Connection CDS

Source:

/DMO/CONNECTION

Source alias:

Connection

Requirements:

• CarrierId is a key;
• ConnectionId is a key;
• expose all fields listed in Part 2;
• calculate RouteCode;
• calculate DeparturePeriod;
• use @AccessControl.authorizationCheck: #NOT_REQUIRED;
• add a useful end-user label.

Use:

Ctrl + Space

for code completion.

---

Part 6 — Check, activate, and preview

Run:

Ctrl + F2

Fix all syntax errors.

Activate:

Ctrl + F3

Preview:

F8

Verify RouteCode and DeparturePeriod for several rows.

Check manually that a departure before 12:00 is classified as Morning.

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Part 7 — SQL Console

Query ZI_CONNECTION_### in SQL Console.

Return:

CarrierId
ConnectionId
RouteCode
DepartureTime
DeparturePeriod

Sort by:

CarrierId
ConnectionId

Then add a SQL Console filter for:

DeparturePeriod = Morning

This filter belongs to that query only.

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Part 8 — Create a filtered CDS entity

Create:

ZI_MORNING_CONNECTION_###

Its source must be:

ZI_CONNECTION_###

not /DMO/CONNECTION.

Expose:

CarrierId
ConnectionId
AirportFromId
AirportToId
DepartureTime
ArrivalTime
Distance
DistanceUnit
RouteCode
DeparturePeriod

Add a CDS WHERE clause so the entity represents only Morning connections.

Use a typed character literal in the condition.

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Part 9 — Activate and compare

Activate the filtered CDS entity.

Preview:

ZI_CONNECTION_###

and:

ZI_MORNING_CONNECTION_###

Answer:

1. Which entity contains all modeled connections?

2. Which entity contains only morning connections?

3. Which entity contains the CASE logic?

4. Does the filtered entity repeat the CASE expression?

It should not.

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Part 10 — Create the Connection Reader

Create:

ZCL_CONNECTION_READER_###

Define two internal-table types:

one based on ZI_CONNECTION_###
one based on ZI_MORNING_CONNECTION_###

Use the CDS entities directly as global structured types.

Suggested names:

TT_CONNECTIONS
TT_MORNING_CONNECTIONS

Both should be standard tables with empty keys.

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Part 11 — Add Reader methods

Create:

GET_ALL
GET_MORNING

GET_ALL returns all modeled connections.

GET_MORNING returns the morning-connection model.

Both methods should:

• use ABAP SQL;
• select from CDS, not the database table;
• sort by CarrierId and ConnectionId.

Because each method returns the complete CDS entity type, FIELDS * is acceptable.

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Part 12 — Create the Runner

Create:

ZCL_CDS_L03_PRACTICE_###

Implement:

IF_OO_ADT_CLASSRUN

In main:

1. create the Connection Reader;
2. call GET_ALL;
3. loop over the returned data;
4. display:

RouteCode - DeparturePeriod

Then call GET_MORNING and display the result.

The Runner should contain no direct:

SELECT FROM /dmo/connection

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Part 13 — Test the classification

Choose at least three connections if your data allows it:

one morning
one afternoon
one evening

Record:

DepartureTime	Expected	Actual

If the demo data does not contain all three periods, use the periods that are present and state which category is absent.

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Part 14 — Reasoning questions

1. What is the difference between a source field and a calculated CDS element?

2. Why is RouteCode defined once in CDS instead of concatenated in every Runner?

3. What does CASE do in this model?

4. What does WHERE do in the morning-connection model?

5. Why is abap.tims'120000' clearer than an untyped time-like literal?

6. Why does ZI_MORNING_CONNECTION_### select from ZI_CONNECTION_### instead of repeating all logic from /DMO/CONNECTION?

7. What is the difference between filtering in SQL Console and creating a filtered CDS View Entity?

8. Can a CDS View Entity be used as an ABAP type?

9. Why is FIELDS * acceptable in the Reader methods in this assignment?

10. Why is * not used in the CDS View Entity element list?

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Optional challenge 1 — Evening model

Create:

ZI_EVENING_CONNECTION_###

by reusing:

ZI_CONNECTION_###

Filter:

DeparturePeriod = Evening

Do not repeat the CASE expression.

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Optional challenge 2 — Investigate another string function

Review the current CDS string-function documentation.

Add one additional calculated element using a different supported string function.

Document:

function used
input element(s)
example result

Do not use joins or associations.

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Submission checklist

• ZI_CONNECTION_### exists.
• It uses /DMO/CONNECTION as its source.
• Both source key fields are exposed as CDS keys.
• RouteCode is calculated with a CDS string function.
• DeparturePeriod is calculated with CASE.
• Typed abap.tims literals are used.
• Typed character literals are used for classification values.
• The base CDS entity activates.
• Data Preview shows the calculated elements.
• SQL Console can query the calculated elements.
• ZI_MORNING_CONNECTION_### exists.
• It uses ZI_CONNECTION_### as its source.
• It filters with CDS WHERE.
• It does not repeat the CASE logic.
• ZCL_CONNECTION_READER_### uses CDS entities as ABAP types.
• GET_ALL selects from ZI_CONNECTION_###.
• GET_MORNING selects from ZI_MORNING_CONNECTION_###.
• The Runner contains no direct database-table SELECT.
• The reasoning questions are answered.

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Useful ADT shortcuts

Action	Shortcut
Open ABAP Development Object	Ctrl + Shift + A
Code completion	Ctrl + Space
Syntax check	Ctrl + F2
Activate current object	Ctrl + F3
Activate inactive objects	Ctrl + Shift + F3
CDS Data Preview	F8
Run console class	F9
Format source	Shift + F1